TW201805438A - Non-heat-treated wire rod for bolt, non-heat-treated steel wire for bolt, and method for manufacturing same, and non-heat-treated bolt - Google Patents
Non-heat-treated wire rod for bolt, non-heat-treated steel wire for bolt, and method for manufacturing same, and non-heat-treated bolt Download PDFInfo
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本發明係關於非熱處理螺栓用線材、非熱處理螺栓用鋼線及彼等之製造方法以及非熱處理螺栓。 The present invention relates to wires for non-heat-treated bolts, steel wires for non-heat-treated bolts, and a method for manufacturing the same, and non-heat-treated bolts.
一直以來，使用於各種緊固零件般之強度等級為70~90kgf/mm2之螺栓，係於冷壓造後藉由實施淬火以及回火之熱處理，而擔保其特定之強度。 Conventionally, bolts with a strength level of 70 to 90 kgf / mm 2 like various fastening parts have been subjected to heat treatment of quenching and tempering after cold pressing to guarantee their specific strength.
然而近年來，基於減少CO2排放及節省能源之觀點，省略上述熱處理，即進行非熱處理化。如此省略熱處理所獲得之非熱處理螺栓，由於可省略上述熱處理及該熱處理後之矯直等步驟，可實現降低成本。進而亦有助於對於螺栓．零件等製造之前置時間縮短及作業環境之改善。 However, in recent years, from the viewpoint of reducing CO 2 emissions and saving energy, the above heat treatment is omitted, that is, non-heat treatment is performed. In this way, the non-heat-treated bolt obtained by heat treatment can be omitted because the steps of the heat treatment and straightening after the heat treatment can be omitted. It also helps for bolts. Reduce the pre-production time of parts and other parts and improve the working environment.
上述非熱處理螺栓，係使用具有配合螺栓強度之強度的鋼線成形為螺栓形狀，具體以冷壓造來製造。自鋼線成形為螺栓，一般係於軸方向施加壓縮力，而形成頭部之冷壓造。因此上述鋼線需可經良好之冷壓造，亦即，必須具有優良之冷壓造性。 The non-heat-treated bolt is formed into a bolt shape using a steel wire having a strength that matches the strength of the bolt, and is specifically manufactured by cold pressing. Forming bolts from steel wire generally applies a compressive force in the axial direction to form a cold-pressed head. Therefore, the above-mentioned steel wire needs to be capable of being subjected to good cold pressing, that is, it must have excellent cold pressability.
此外獲得供於非熱處理螺栓之高強度鋼線(絲)，有使用提高抽線減面率之方法。若於螺栓形成中使用提高抽線減面率而確保強度之鋼線，則由於因包辛格效應(Bauschinger effect)而使螺栓形成時之壓造荷重降低，故可延長螺栓形成時之工具壽命。然而，藉由上述抽線而高強度化之鋼線，亦因包辛格效應而使降伏點降低，使所獲得之螺栓難以達到所要求之高強度比，其結果為引起限制螺栓緊固時之軸力上限值以及無法滿足以鋼製緊固零件機械特性(JIS B1051)所決定之保證荷重試驗中之永久伸長度等問題。 In addition, to obtain high-strength steel wires (wires) for non-heat-treated bolts, there are methods to increase the drawdown reduction rate. If a steel wire is used in bolt formation to increase the drawdown and surface reduction rate to ensure strength, the pressing load during bolt formation is reduced due to the Bauschinger effect, which can prolong the tool life during bolt formation. . However, the steel wire made high-strength by the above-mentioned drawing wire also lowers the drop point due to the Bauschinger effect, making it difficult for the obtained bolts to achieve the required high strength ratio. As a result, when restricting the tightening of the bolts The upper limit of the axial force and the failure to meet the permanent elongation in the guaranteed load test determined by the mechanical characteristics of the steel fastening parts (JIS B1051).
一直以來為解決上述問題，於例如專利文獻1所示，於螺栓壓造後，藉由於約350℃加熱進行發藍(bluing)處理，而去除應力，同時提高降伏強度。此外作為螺栓形成後之防鏽表面處理，係於約300℃以上進行以鋅粉燒附塗裝之Geomet(註冊商標)處理。然而，上述發藍處理等，與前述淬火回火之熱處理同樣耗費成本，無法期望達到非熱處理化之成本優勢。 In order to solve the above-mentioned problems, as shown in, for example, Patent Document 1, after a bolt is pressed, a bluing process is performed by heating at about 350 ° C. to remove stress and increase the drop strength. In addition, as a rust-preventive surface treatment after bolt formation, a Geomet (registered trademark) treatment with zinc powder firing and coating was performed at about 300 ° C or higher. However, the above-mentioned bluing treatment and the like consume the same cost as the aforementioned heat treatment of quenching and tempering, and it cannot be expected to achieve the cost advantage of non-heat treatment.
本發明人亦於專利文獻2中提案不進行熱處理而以直接形成螺栓之狀態，亦即謀求非熱處理螺栓之高強度及抗延遲破壞性提升之技術。然而，於非熱處理螺栓之與高強度一起確實達成更高強度比則需要進一步檢討。 The present inventor also proposed in the patent document 2 that the bolts are directly formed without heat treatment, that is, a technology that seeks to improve the high strength and delayed destructive resistance of non-heat-treated bolts. However, the fact that non-heat-treated bolts together with high strength do reach a higher strength ratio requires further review.
[專利文獻1]日本專利特開平08-003640號公報 [Patent Document 1] Japanese Patent Laid-Open No. 08-003640
[專利文獻2]日本專利特開2003-113444號公報 [Patent Document 2] Japanese Patent Laid-Open No. 2003-113444
本發明之實施形態係鑑於如上述情況而完成者，其目的在於提供即使不進行焠火回火、發藍處理等高溫之熱處理，抗拉強度亦為780MPa以上1200MPa以下，且強度比為0.80以上，進而具備抗延遲破壞性之非熱處理螺栓，及製造該非熱處理螺栓用之非熱處理螺栓用線材、鋼線、以及前述非熱處理螺栓與非熱處理螺栓用線材、鋼線之各製造方法。又以下，非熱處理螺栓、非熱處理螺栓用線材．鋼線，有時分別簡稱為「螺栓」、「螺栓用線材．鋼線」。 The embodiment of the present invention is completed in view of the above situation, and its purpose is to provide a tensile strength of 780 MPa or more and 1200 MPa or less, and a strength ratio of 0.80 or more, even if no high temperature heat treatment such as quenching and tempering or bluing is performed. Furthermore, it is provided with a non-heat-treated bolt with resistance to delayed destructive properties, and a non-heat-treated bolt wire and steel wire for manufacturing the non-heat-treated bolt, and each of the above-mentioned manufacturing methods of the non-heat-treated bolt and the non-heat-treated bolt wire and steel wire. In the following, non-heat-treated bolts and wires for non-heat-treated bolts. Steel wires are sometimes referred to as "bolts" and "wires for bolts. Steel wires."
可解決上述課題之本發明實施形態之非熱處理螺栓用線材，其特徵係成分組成，以質量%計，滿足C：0.05~0.30%、Si：1.10~2.5%、Mn：0.50~2.5%、P：超過0%，0.03%以下、S：超過0%，0.03%以下、Cr：0.03~0.30%、 Al：0.010~0.10%、及N：0.0020~0.0100%，其餘部分為鐵及不可避免之雜質所成，以下述式(1)表示之碳當量Ceq為0.60以上0.80以下，肥粒鐵(Ferrite)於全組織中所佔之面積率為60%以上，且波來鐵(Pearlite)於全組織中所佔之面積率為5%以上，此外，肥粒鐵之結晶粒度號為10號以上，Ceq=[C]+[Si]/7+[Mn]/5+[Cr]/9...(1) The wire for non-heat-treated bolts according to the embodiment of the present invention that can solve the above-mentioned problems, has a characteristic composition of components, and meets C: 0.05 to 0.30%, Si: 1.10 to 2.5%, Mn: 0.50 to 2.5%, P : More than 0%, 0.03% or less, S: more than 0%, 0.03% or less, Cr: 0.03 to 0.30%, Al: 0.010 ~ 0.10% and N: 0.0020 ~ 0.0100%. The rest is made of iron and unavoidable impurities. The carbon equivalent Ceq represented by the following formula (1) is 0.60 or more and 0.80 or less. Ferrite The area ratio in the whole organization is more than 60%, and the area ratio of Pearlite in the whole organization is more than 5%. In addition, the crystal grain size number of the ferrous iron is more than 10, Ceq = [C] + [Si] / 7 + [Mn] / 5 + [Cr] / 9 ... (1)
上述式(1)中，[元素]表示鋼中各元素以質量%計之含量。 [Element] in the above formula (1) represents the content of each element in the steel in terms of mass%.
且可解決上述課題之本發明實施形態之非熱處理螺栓用線材之製造方法，其特徵為使用滿足前述成分組成之鋼材，將壓延時之加熱溫度設為1000℃以上1200℃以下，且熱壓延後，自800℃至500℃之平均冷卻速度設為2.0~5.0℃/秒。 The method for manufacturing a non-heat-treated bolt wire according to the embodiment of the present invention that can solve the above-mentioned problems is characterized in that a steel material that satisfies the aforementioned composition is used, the heating temperature for the rolling delay is set to 1000 ° C or higher and 1200 ° C or lower, and the heat rolling Thereafter, the average cooling rate from 800 ° C to 500 ° C is set to 2.0 to 5.0 ° C / sec.
可解決上述課題之本發明實施形態之非熱處理螺栓用鋼線，其特徵係成分組成以質量%計，滿足C：0.05~0.30%、Si：1.10~2.5%、Mn：0.50~2.5%、P：超過0%，0.03%以下、S：超過0%，0.03%以下、Cr：0.03~0.30%、Al：0.010~0.10%、及 N：0.0020~0.0100%，其餘部分為鐵及不可避免之雜質所成，以下述式(1)表示之碳當量Ceq為0.60以上0.80以下，肥粒鐵於全組織中所佔之面積率為60%以上，且波來鐵於全組織中所佔之面積率為5%以上，此外，肥粒鐵之結晶粒度號為10號以上，Ceq=[C]+[Si]/7+[Mn]/5+[Cr]/9...(1) The steel wire for non-heat-treated bolts according to the embodiment of the present invention that can solve the above-mentioned problems, the characteristic composition of which is in terms of mass%, and satisfies C: 0.05 to 0.30%, Si: 1.10 to 2.5%, Mn: 0.50 to 2.5%, P : More than 0%, 0.03% or less, S: more than 0%, 0.03% or less, Cr: 0.03 to 0.30%, Al: 0.010 to 0.10%, and N: 0.0020 ~ 0.0100%, the rest is made of iron and unavoidable impurities. The carbon equivalent Ceq represented by the following formula (1) is 0.60 or more and 0.80 or less. The area ratio of the fertile iron in the whole organization is 60. %, And the area ratio of boron iron in the whole organization is more than 5%. In addition, the grain size number of ferrous iron is 10 or more, Ceq = [C] + [Si] / 7 + [Mn] /5+[Cr]/9...(1)
上述式(1)中，[元素]表示鋼中各元素以質量%計之含量。 [Element] in the above formula (1) represents the content of each element in the steel in terms of mass%.
又可解決上述課題之本發明實施形態之製造非熱處理螺栓用鋼線之方法，其特徵為使用前述非熱處理螺栓用線材，以抽線減面率20~40%進行抽線。 The method for manufacturing a non-heat-treated bolt steel wire according to the embodiment of the present invention that can solve the above-mentioned problems is characterized in that the non-heat-treated bolt wire is used, and the wire is drawn at a reduction rate of 20 to 40%.
此外，可解決上述課題之本發明實施形態之非熱處理螺栓，其特徵係成分組成，以質量%計，滿足C：0.05~0.30%、Si：1.10~2.5%、Mn：0.50~2.5%、P：超過0%，0.03%以下、S：超過0%，0.03%以下、Cr：0.03~0.30%、Al：0.010~0.10%、及N：0.0020~0.0100%，其餘部分為鐵及不可避免之雜質所成，以下述式(1)表示之碳當量Ceq為0.60以上0.80以下， 肥粒鐵於全組織中所佔之面積率為60%以上且波來鐵於全組織中所佔之面積率為5%以上，此外，肥粒鐵之結晶粒度號為10號以上，Ceq=[C]+[Si]/7+[Mn]/5+[Cr]/9...(1) In addition, the non-heat-treated bolt of the embodiment of the present invention that can solve the above-mentioned problems has a characteristic composition of components, in terms of mass%, which satisfies C: 0.05 to 0.30%, Si: 1.10 to 2.5%, Mn: 0.50 to 2.5%, P : More than 0%, 0.03% or less, S: more than 0%, 0.03% or less, Cr: 0.03 ~ 0.30%, Al: 0.010 ~ 0.10%, and N: 0.0020 ~ 0.0100%, the rest is iron and unavoidable impurities The carbon equivalent Ceq represented by the following formula (1) is 0.60 or more and 0.80 or less. The area ratio of ferrous iron in the whole organization is more than 60% and the area ratio of boron iron in the whole organization is more than 5%. In addition, the grain size number of the ferrous iron is more than 10, Ceq = [C] + [Si] / 7 + [Mn] / 5 + [Cr] / 9 ... (1)
上述式(1)中，[元素]表示鋼中各元素以質量%計之含量。 [Element] in the above formula (1) represents the content of each element in the steel in terms of mass%.
前述非熱處理螺栓，較佳於滿足抗拉強度為780MPa以上1200MPa以下，且強度比為0.80以上。 The non-heat-treated bolt preferably satisfies a tensile strength of 780 MPa or more and 1200 MPa or less and a strength ratio of 0.80 or more.
根據本發明之實施形態，可提供即使不進行焠火回火、發藍處理等高溫之熱處理，抗拉強度亦為780MPa以上1200MPa以下，且強度比為0.80以上，進而具備抗延遲破壞性之非熱處理螺栓、及製造該非熱處理螺栓用之非熱處理螺栓用線材．鋼線，以及彼等製造方法。 According to the embodiment of the present invention, even if no high-temperature heat treatment such as quenching and tempering and bluing treatment is performed, a non-heat treatment with a tensile strength of 780 MPa or more and 1200 MPa or less and a strength ratio of 0.80 or more can be provided. Bolts, and wires for non-heat-treated bolts used to make the non-heat-treated bolts. Steel wire, and their manufacturing methods.
本發明人等為了解決前述課題而重複積極研究。其結果發現非熱處理螺栓之成分組成及組織只要為如下述即可，亦即只要具有所希望之成分組成，肥粒鐵之面積率為60%以上，且波來鐵之面積率為5%以上，肥粒鐵之結晶粒度號為10號以上即可。此外亦發現，對於該螺栓之組織，只要使供於螺栓製造之線材．鋼線之組織與下述螺栓之組織相同即可，亦即，只要對線材．鋼線進行加 工等而於組織無太大變化，可於線材的階段得到與下述螺栓組織相同之組織即可，因而完成本發明之實施形態。 The present inventors have repeatedly and actively studied in order to solve the aforementioned problems. As a result, it was found that the composition and structure of the non-heat-treated bolt may be as follows, that is, as long as it has a desired composition, the area ratio of the ferrous iron is 60% or more, and the area ratio of the boron iron is 5% or more. , The grain size of the ferrous iron can be 10 or more. In addition, it has been found that for the organization of the bolt, as long as the wire used for the manufacture of the bolt. The structure of the steel wire is the same as that of the bolts described below, that is, as long as the wire. Steel wire There is not much change in the structure, etc., and the same structure as the bolt structure described below can be obtained at the stage of the wire, so the embodiment of the present invention is completed.
本發明實施形態之螺栓及螺栓用線材．鋼線係組織為肥粒鐵及波來鐵之2相組織，可均衡良好地提高抗拉強度及強度比，進而較佳地為提高永久伸長度者。基於該等觀點，首先肥粒鐵於全組織中所佔之面積率需為60%以上。該肥粒鐵之面積率，較佳為62%以上，更佳為65%以上。又，肥粒鐵之面積率之上限，若考慮下述波來鐵之面積率則為95%以下，較佳為94%以下，更佳為93%以下。 Bolts and bolt wires for the embodiments of the present invention. The steel wire structure is a two-phase structure of ferrous iron and boron iron, which can improve the tensile strength and strength ratio in a well-balanced manner, and is more preferably a permanent elongation. Based on these points of view, firstly, the area ratio of fertilized iron in the whole organization needs to be 60% or more. The area ratio of the ferrous iron is preferably 62% or more, and more preferably 65% or more. In addition, the upper limit of the area ratio of ferrous iron is 95% or less, preferably 94% or less, and more preferably 93% or less in consideration of the area ratio of the following boron iron.
此外，為特別提高強度比，波來鐵於全組織中所佔之面積率為5%以上。該波來鐵之面積率，較佳為6%以上，更佳為7%以上。此波來鐵之面積率之上限，若考慮上述肥粒鐵之面積率則為40%以下，較佳為38%以下，更佳為35%以下。 In addition, in order to increase the intensity ratio in particular, the area ratio of the boron iron in the entire organization is more than 5%. The area ratio of the wave iron is preferably 6% or more, and more preferably 7% or more. The upper limit of the area ratio of this wave of iron is 40% or less, preferably 38% or less, and more preferably 35% or less in consideration of the area ratio of the fertilized iron.
本發明實施形態之螺栓及螺栓用線材．鋼線，除了組織係由肥粒鐵及波來鐵所成以外，於上述肥粒鐵及波來鐵中，亦有於全組織中佔面積率5%以下含有製造步驟中不可避免形成之變韌鐵(Bainite)及麻田散鐵(Martensite)等組織之情況。此外，在含有變韌鐵等組織之情況下，於可判別該組織之面積率及肥粒鐵之面積率時，波來鐵之面積率係自100%減去變韌鐵等之組織之面積率及肥粒鐵之面積率而求得。 Bolts and bolt wires for the embodiments of the present invention. In addition to the structure of steel wire made of ferrous iron and bolai iron, the above-mentioned ferrous iron and bolai iron also account for less than 5% of the area ratio in the entire structure. Status of organizations such as Bainite and Martensite. In addition, in the case of a structure containing toughened iron, etc., when the area ratio of the structure and the area ratio of ferrous iron can be discriminated, the area ratio of the boron iron is 100% minus the area of the structure such as the toughened iron. And the area ratio of ferrous iron.
為了改善強度比，肥粒鐵結晶粒度號設為10號以上。肥粒鐵結晶粒度號，較佳為10.3號以上，更佳為10.5號以上。由於肥粒鐵結晶粒度越微細越可改善機械特性，因此並未特別限定肥粒鐵之結晶粒度號上限。然而，若考慮本發明實施形態之成分組成及製造方法，則肥粒鐵結晶粒度號之上限較佳約為12號左右。 In order to improve the strength ratio, the grain size number of the ferrous iron is set to 10 or more. The grain size of the ferrous iron is preferably 10.3 or more, and more preferably 10.5 or more. As the grain size of fertilizer iron is finer, the mechanical properties can be improved, so the upper limit of the grain size number of fertilizer iron is not particularly limited. However, considering the component composition and manufacturing method according to the embodiment of the present invention, the upper limit of the grain size number of the ferrous grain iron is preferably about 12.
接著，針對規定本發明實施形態之非熱處理螺栓及非熱處理螺栓用線材．鋼線之成分組成範圍之理由敘述如下。 Next, the non-heat-treated bolts and wires for non-heat-treated bolts that define the embodiments of the present invention are described. The reason for the composition range of the steel wire is described below.
C為確保鋼強度之必要元素。為了達成目標之螺栓之抗拉強度：780MPa以上，C量下限設為0.05%。C量較佳為0.10%以上，更佳為0.15%以上。另一方面，若C含量過剩，則熱壓延前之加熱時未固溶碳化物殘留較多，其結果為無法確保充分之肥粒鐵，而無法獲得期望之強度比。此外，亦有螺栓之抗拉強度超過上限1200MPa之虞。因此，C量之上限設為0.30%。C量較佳為0.25%以下，更佳為0.20%以下。 C is an essential element to ensure the strength of the steel. In order to achieve the target tensile strength of the bolt: above 780 MPa, the lower limit of the amount of C is set to 0.05%. The amount of C is preferably 0.10% or more, and more preferably 0.15% or more. On the other hand, if the C content is excessive, there will be a large amount of undissolved carbides remaining during heating before hot rolling. As a result, sufficient ferrous iron cannot be secured, and a desired strength ratio cannot be obtained. In addition, there is a possibility that the tensile strength of the bolt exceeds the upper limit of 1200 MPa. Therefore, the upper limit of the amount of C is set to 0.30%. The amount of C is preferably 0.25% or less, and more preferably 0.20% or less.
Si作為脫氧劑發揮作用，同時亦是確保鋼強度之必要 元素。又，Si亦係抑制粗大雪明碳鐵(Cementite)析出，並提升抗延遲破壞性之元素。此外，Si於一定添加量下，亦可減低永久伸長度。為了獲得此等效果，Si量之下限設為1.10%。Si量較佳為1.20%以上，更佳為1.30%以上，又更佳為1.50%以上。本發明之實施形態，基於確保鋼強度同時降低永久伸長度之觀點，相較過往之非熱處理螺栓，更增加Si添加量。另一方面，若Si含量過剩，由於有螺栓之抗拉強度超過上限1200MPa之虞，故Si量之上限設為2.5%。Si量較佳為2.20%以下，更佳為2.00%以下。 Si acts as a deoxidizer and is necessary to ensure the strength of the steel element. In addition, Si is an element that suppresses precipitation of coarse Cementite and improves resistance to delayed destructive properties. In addition, Si can also reduce the permanent elongation at a certain amount of addition. In order to obtain these effects, the lower limit of the amount of Si is set to 1.10%. The amount of Si is preferably 1.20% or more, more preferably 1.30% or more, and even more preferably 1.50% or more. In the embodiment of the present invention, from the viewpoint of ensuring the strength of the steel while reducing the permanent elongation, the amount of Si added is increased compared to the conventional non-heat-treated bolts. On the other hand, if the Si content is excessive, the tensile strength of the bolt may exceed the upper limit of 1200 MPa, so the upper limit of the amount of Si is set to 2.5%. The amount of Si is preferably 2.20% or less, and more preferably 2.00% or less.
Mn為確保鋼強度，同時具有作為脫氧劑之效果。為了獲得該等效果，Mn量之下限設為0.50%。Mn量較佳為0.75%以上，更佳為1.00%以上。另一方面，若Mn含量過剩，則產生Mn偏析，而生成麻田散鐵之過冷組織使抽線加工性劣化。因此，Mn量之上限設為2.5%。Mn量較佳為2.20%以下，更佳為2.00%以下。 Mn is used as a deoxidizer to ensure the strength of steel. In order to obtain these effects, the lower limit of the amount of Mn is set to 0.50%. The amount of Mn is preferably 0.75% or more, and more preferably 1.00% or more. On the other hand, if the Mn content is excessive, Mn segregation occurs, and a supercooled structure of Asada scattered iron is generated, which deteriorates wire drawing processability. Therefore, the upper limit of the amount of Mn is set to 2.5%. The Mn content is preferably 2.20% or less, and more preferably 2.00% or less.
P係使晶界偏析並造成可冷鍛性惡化之元素。此外亦為導致抗延遲破壞性降低之元素。因此將P量抑制於0.03%以下。P量較佳為0.015%以下，更佳為0.010%以下。雖P量越少越佳，但製造上難以達到0%，通常至少含有0.003%左右。 P is an element that segregates grain boundaries and causes deterioration of cold forgeability. It is also an element that causes a reduction in the destructive resistance to delay. Therefore, the amount of P is suppressed to 0.03% or less. The amount of P is preferably 0.015% or less, and more preferably 0.010% or less. Although the smaller the amount of P, the better, but it is difficult to reach 0% in production, and usually it contains at least about 0.003%.
S會於晶界上變濃而形成MnS，使該處成為應力集中部位而產生裂縫導致抗延遲破壞性降低。因此，將S量抑制於0.03%以下。S量較佳為0.015%以下，更佳為0.010%以下。雖S量越少越佳，但製造上難以達到0%，通常至少含有0.003%左右。 S will be thickened at the grain boundaries to form MnS, which will become a stress concentration site and cracks will occur, resulting in a decrease in delayed destructive resistance. Therefore, the amount of S is suppressed to 0.03% or less. The amount of S is preferably 0.015% or less, and more preferably 0.010% or less. Although the smaller the amount of S, the better, but it is difficult to achieve 0% in production, and it usually contains at least about 0.003%.
Cr係為確保強度之元素，於經鍍敷處理時進行之烘烤處理時再析出，亦具有抑制強度降低之效果。為了獲得該等效果，將Cr量之下限設為0.03%。Cr量較佳為0.05%以上，更佳為0.07%以上，又更佳為0.10%以上。另一方面，若Cr含量過剩，由於效果趨於飽和，同時亦導致成本增加，故Cr量之上限設為0.30%。Cr量較佳為0.25%以下，更佳為0.20%以下。 Cr is an element for ensuring strength, and it is precipitated again during the baking treatment performed during the plating treatment, and also has the effect of suppressing the decrease in strength. In order to obtain these effects, the lower limit of the amount of Cr is set to 0.03%. The amount of Cr is preferably 0.05% or more, more preferably 0.07% or more, and still more preferably 0.10% or more. On the other hand, if the content of Cr is excessive, the effect tends to be saturated and the cost is increased. Therefore, the upper limit of the amount of Cr is set to 0.30%. The amount of Cr is preferably 0.25% or less, and more preferably 0.20% or less.
Al係作為脫氧劑使用之元素。此外，亦可形成氮化物並藉由釘扎效應(Pinning Effect)而防止舊沃斯田鐵(Austenite)晶粒粗大化，同時藉由晶粒微細化而確保強度之有效元素。為了獲得該等效果，Al量之下限設為0.010%。Al量較佳為0.015%以上，更佳為0.020%以上。另一方面，若Al過量含有，由於會形成粗大的氮化物而 使疲勞特性惡化，因此Al量之上限設為0.10%。Al量較佳為0.08%以下，更佳於0.06%以下。 Al is an element used as a deoxidizer. In addition, it is an effective element that can form nitrides and prevent the coarsening of the grains of old Austenite by the pinning effect, and at the same time ensure the strength by miniaturizing the grains. In order to obtain these effects, the lower limit of the amount of Al is set to 0.010%. The amount of Al is preferably 0.015% or more, and more preferably 0.020% or more. On the other hand, if Al is contained excessively, coarse nitrides are formed and Since the fatigue characteristics are deteriorated, the upper limit of the amount of Al is set to 0.10%. The amount of Al is preferably 0.08% or less, and more preferably 0.06% or less.
N係肥粒鐵中析出之碳氮化物之構成元素，並藉由釘扎效應防止舊沃斯田鐵晶粒粗大化。為了獲得該等效果，N量之下限設為0.0020%。N量較佳為0.0030%以上，更佳為0.0035%以上。另一方面，若N過量含有則會生成粗大的氮化物，使疲勞特性惡化。因此N量之上限設為0.0100%。N量較佳為0.0080%以下，更佳為0.0060%以下。 The constituent elements of carbonitrides precipitated in N-type ferrous iron, and the grain size of old Vosted iron is prevented by the pinning effect. In order to obtain these effects, the lower limit of the amount of N is set to 0.0020%. The amount of N is preferably 0.0030% or more, and more preferably 0.0035% or more. On the other hand, if N is contained excessively, coarse nitrides are formed, which deteriorates fatigue characteristics. Therefore, the upper limit of the amount of N is set to 0.0100%. The amount of N is preferably 0.0080% or less, and more preferably 0.0060% or less.
本發明實施形態之螺栓及螺栓用線材．鋼線之成分如上述，其餘部分為鐵及不可避免之雜質。前述不可避免之雜質，可能為原料及製造過程中混入者，亦可以對於構成螺栓及螺栓用線材．鋼線之鋼之諸特性無害之程度含有。例如作為前述不可避免之雜質，可含有Ni於0.03%以下，較佳於0.02%以下，Cu於0.03%以下，較佳於0.02%以下。此外，亦可含有V於0.02%以下，Nb於0.02%以下，Ti於0.02%以下作為不可避免之雜質。若積極採用該等V、Nb及Ti，由於製造階段中，必使析出物形態變得難以控制，因此於本發明之實施形態中，抑制為如上述之不可避免雜質程度。如此本發明之實施形態，於不積極地添加V等而謀求析出強化之方面與專利文獻2不同。 Bolts and bolt wires for the embodiments of the present invention. The composition of the steel wire is as described above, and the rest is iron and unavoidable impurities. The aforementioned unavoidable impurities may be mixed in the raw materials and manufacturing process, and may also be used to constitute bolts and wire for bolts. The steel wire is contained to such an extent that the characteristics of the steel are not harmful. For example, the aforementioned unavoidable impurities may contain Ni below 0.03%, preferably below 0.02%, and Cu below 0.03%, preferably below 0.02%. In addition, V may be 0.02% or less, Nb 0.02% or less, and Ti 0.02% or less may be contained as unavoidable impurities. If these V, Nb, and Ti are actively used, it is difficult to control the morphology of the precipitates during the manufacturing stage. Therefore, in the embodiment of the present invention, the unavoidable impurity level as described above is suppressed. As described above, the embodiment of the present invention is different from Patent Document 2 in that precipitation strengthening is not actively added by adding V or the like.
Ceq=[C]+[Si]/7+[Mn]/5+[Cr]/9...(1) Ceq = [C] + [Si] / 7 + [Mn] / 5 + [Cr] / 9 ... (1)
上述式(1)中，[元素]表示鋼中各元素以質量%計之含量。 [Element] in the above formula (1) represents the content of each element in the steel in terms of mass%.
為使螺栓強度設為以JIS B1051(2012年)或JIS B1051(2015年)定義之強度區分8.8~10.9級，且強度比為0.80以上，故本發明實施形態之螺栓及螺栓用線材．鋼線之以上述式(1)表示之碳當量Ceq設為0.60以上0.80以下。上述碳當量Ceq較佳為0.65以上，更佳為0.70以上，較佳為0.78以下。 In order to set the bolt strength to 8.8 to 10.9 grades according to the strength defined by JIS B1051 (2012) or JIS B1051 (2015), and the strength ratio is 0.80 or more, the bolts and bolt wires of the embodiment of the present invention. The carbon equivalent Ceq of the steel wire represented by the above formula (1) is set to 0.60 or more and 0.80 or less. The carbon equivalent Ceq is preferably 0.65 or more, more preferably 0.70 or more, and more preferably 0.78 or less.
作為JIS B1051(2012年)或JIS B1051(2015年)中定義之強度區分8.8~10.9級之螺栓，螺栓之抗拉強度係設為780MPa以上1200MPa以下。螺栓之抗拉強度較佳為800MPa以上，更佳為850MPa以上，又更佳為900MPa以上；較佳為1100MPa以下，更佳為1000MPa以下。 As a bolt defined by JIS B1051 (2012) or JIS B1051 (2015) with a strength classification of 8.8 to 10.9, the tensile strength of the bolt is set to 780 MPa to 1200 MPa. The tensile strength of the bolt is preferably 800 MPa or more, more preferably 850 MPa or more, and still more preferably 900 MPa or more; preferably 1100 MPa or less, and more preferably 1000 MPa or less.
為了確保緊固部分之高螺栓軸向力、降低螺栓使用根數及可使螺栓緊固零件輕量化，其雖取決於抗拉強度，但 螺栓之0.2%強度較佳為870MPa以上，更佳為880MPa以上，螺栓之0.01%強度較佳為660MPa以上，更佳為670MPa以上。強度係越高越佳，但若考慮本發明實施形態之成分組成及製造方式，螺栓之0.2%強度上限為900MPa左右，螺栓之0.01%強度上限為690MPa左右。 In order to ensure high bolt axial force in the fastening part, reduce the number of bolts used, and make the bolt fastening parts lighter, it depends on the tensile strength, but The 0.2% strength of the bolt is preferably 870 MPa or more, more preferably 880 MPa or more, and the 0.01% strength of the bolt is preferably 660 MPa or more, and more preferably 670 MPa or more. The higher the strength, the better, but if the component composition and manufacturing method of the embodiment of the present invention are considered, the upper limit of the 0.2% strength of the bolt is about 900MPa, and the upper limit of the 0.01% strength of the bolt is about 690MPa.
本發明之實施形態中，藉由將強度比設為0.80以上，可抑制前述之保證荷重試驗中之永久伸長度。強度比較佳為0.85以上，更佳為0.90以上。 In the embodiment of the present invention, by setting the strength ratio to 0.80 or more, the permanent elongation in the aforementioned guaranteed load test can be suppressed. The strength is preferably 0.85 or more, and more preferably 0.90 or more.
本發明實施形態之非熱處理螺栓用線材．鋼線及非熱處理螺栓，可藉由以下步驟製造。 The wire for non-heat-treated bolts according to the embodiment of the present invention. Steel wires and non-heat treated bolts can be manufactured by the following steps.
為使存在於鋼中之碳化物固溶，生成均一之沃斯田鐵組織，熱壓延時之加熱溫度設為1000℃以上。該加熱溫度較佳為1010℃以上，更佳為1015℃以上。另一方面，由於加熱溫度過高時使晶粒粗大化，使螺栓之機械特性惡化，故其上限為1200℃。上述加熱溫度較佳為1190℃以下，更佳為1185℃以下。 In order to make the carbides present in the steel solid solution and form a uniform Vosstian iron structure, the heating temperature for the hot pressing delay is set to be above 1000 ° C. The heating temperature is preferably 1010 ° C or higher, and more preferably 1015 ° C or higher. On the other hand, since the grains are coarsened when the heating temperature is too high, and the mechanical characteristics of the bolt are deteriorated, the upper limit is 1200 ° C. The heating temperature is preferably 1190 ° C or lower, and more preferably 1185 ° C or lower.
於上述加熱溫度加熱後進行熱壓延。熱壓延之壓延條件並無特別限定，可採用一般條件。熱壓延後如 下述冷卻。 After heating at the above heating temperature, hot rolling is performed. The rolling conditions for the hot rolling are not particularly limited, and general conditions can be adopted. After hot rolling, such as The following cooling.
若熱壓延後之冷卻速度過快，則生成變韌鐵、麻田散鐵等硬質組織，使冷壓造性降低。本發明之實施形態中，為獲得滿足肥粒鐵之面積率為60%以上且波來鐵之面積率為5%以上之肥粒鐵及波來鐵之2相組織，將上述溫度範圍中之平均冷卻速度設為5.0℃/秒以下。該平均冷卻速度較佳為4.8℃/秒以下，更佳為4.5℃/秒以下，又更佳為4.2℃/秒以下。另一方面，上述平均冷卻速度之下限，基於確保強度之觀點，設為2.0℃/秒以上。該平均冷卻速度較佳為2.3℃/秒以上，更佳為2.5℃/秒以上，又更佳為2.7℃/秒以上。又，上述自500℃至室溫之冷卻並無特別限定，例如可進行放冷。 If the cooling speed after hot rolling is too fast, hard structures such as toughened iron and Asada loose iron will be formed, and the cold pressability will be reduced. In the embodiment of the present invention, in order to obtain a two-phase structure of fertilized iron and polyarc iron that satisfies an area ratio of 60% or more of ferrous iron and an area ratio of 5% or more of polyarc iron, The average cooling rate is set to 5.0 ° C / second or less. The average cooling rate is preferably 4.8 ° C / second or lower, more preferably 4.5 ° C / second or lower, and even more preferably 4.2 ° C / second or lower. On the other hand, the lower limit of the average cooling rate is 2.0 ° C./sec or more from the viewpoint of ensuring strength. The average cooling rate is preferably 2.3 ° C / second or higher, more preferably 2.5 ° C / second or higher, and even more preferably 2.7 ° C / second or higher. The cooling from 500 ° C to room temperature is not particularly limited, and for example, cooling can be performed.
本發明實施形態之非熱處理螺栓用鋼線，可使用以上述條件製造之線材，以下述條件進行抽線而獲得。 The steel wire for non-heat-treated bolts according to the embodiment of the present invention can be obtained by drawing a wire under the following conditions using a wire manufactured under the above conditions.
為了確保強度同時提高抗延遲破壞性，抽線減面率之下限設為20%。抽線減面率較佳為20.5%以上，更佳為21.0%以上。另一方面，若抽線減面率變得過高，則鋼線之強度過度升高而使冷鍛造性惡化。因此，抽線減面率之上限設為40%。抽線減面率較佳為39.0%以下，更佳為 38.0%以下。此外，抽線減面率係藉由下述式(2)算得之值。 In order to ensure the strength and increase the resistance to delay damage, the lower limit of the draw line reduction rate is set to 20%. The draw-line reduction rate is preferably 20.5% or more, and more preferably 21.0% or more. On the other hand, if the draw-line reduction rate becomes too high, the strength of the steel wire excessively increases, and the cold forgeability is deteriorated. Therefore, the upper limit of the draw reduction rate is set to 40%. The draw line reduction rate is preferably less than 39.0%, and more preferably Below 38.0%. The draw line reduction area ratio is a value calculated by the following formula (2).
抽線減面率=100×[(線材直徑)2-(鋼線直徑)2]/(線材直徑)2...(2) Line reduction rate = 100 × [(wire diameter) 2- (steel wire diameter) 2 ] / (wire diameter) 2 ... (2)
進行上述抽線而獲得之鋼線之抗拉強度約為750~990MPa。使用該鋼線製造螺栓之方法並無特別限定，只要如通常進行般，藉由冷壓造形成螺栓形狀後，轉造螺紋部而製造螺栓即可。然而本發明之實施形態，如前述，不包含如淬火回火、藍化處理等之於約300℃以上之高溫的熱處理。 The tensile strength of the steel wire obtained by performing the above drawing is about 750 to 990 MPa. The method of manufacturing a bolt using this steel wire is not particularly limited, as long as the bolt shape is formed by cold pressing as usual, and then the threaded portion is converted to manufacture the bolt. However, the embodiment of the present invention does not include a heat treatment at a high temperature of about 300 ° C or higher, such as quenching and tempering, blue treatment, and the like.
於使用於需要高耐腐蝕性之用途時，較好施以鋅系之表面處理，例如實施鋅鍍敷處理。實施鋅鍍敷處理時，由於電解時氫被吸留，故於鋅鍍敷後為了脫氫，較好於加熱溫度：100℃及未達300℃，更佳於200℃以下進行加熱時間120~300分鐘之加熱。若加熱溫度過高，則無法期望非熱處理所致之成本優勢，亦會將鋅溶融。 When used for applications requiring high corrosion resistance, a zinc-based surface treatment is preferably applied, such as zinc plating. When zinc plating is performed, hydrogen is occluded during electrolysis. Therefore, for dehydrogenation after zinc plating, the heating temperature is preferably 100 ° C and less than 300 ° C, and the heating time is preferably 200 ° C or lower for 120 ~ Heat for 300 minutes. If the heating temperature is too high, the cost advantage due to non-heat treatment cannot be expected, and zinc will also be melted.
若為熟知以上說明之本發明實施形態之非熱處理螺栓用鋼線之製造方法之該技術人員，則有可藉由嘗試錯誤法，藉由與上述製造方法不同之製造方法獲得本發明中之非熱處理螺栓用鋼線之可能性。 Those skilled in the art who are familiar with the manufacturing method of the non-heat-treated steel wire for bolts according to the embodiments of the present invention described above can obtain the non-ferrous metals in the present invention by trial and error and by manufacturing methods different from those described above. Possibility of heat treatment of steel wire for bolts.
本發明實施形態之非熱處理螺栓，可較好地用於汽車、各種產業機械等。若使用本發明實施形態之非熱處理螺栓用鋼，如同上述，無需進行淬火回火、發藍處理等熱處理，亦可便宜且容易地製造顯示特別高抗拉強度 及高強度比之非熱處理螺栓。 The non-heat-treated bolt according to the embodiment of the present invention can be suitably used in automobiles, various industrial machinery, and the like. If the non-heat-treated bolt steel according to the embodiment of the present invention is used, as described above, heat treatment such as quenching and tempering and bluing treatment is not required, and it can be manufactured inexpensively and easily and exhibit particularly high tensile strength. And high strength ratio of non heat treated bolts.
以下，雖列舉實施例以具體說明本發明之實施形態，但本發明並不限制於下述實施例，於可適於上下文主旨之範圍內，亦可加上變更並實施，此等皆包含於本發明之技術範圍中。 In the following, examples are given to specifically describe the embodiments of the present invention, but the present invention is not limited to the following examples, and can be modified and implemented within the scope suitable for the subject matter of the context, which are all included in Within the technical scope of the present invention.
溶製滿足下述表1所示之成分組成(其餘部分為鐵及不可避免之雜質，空白欄表示未添加)之鋼材。然後使用該鋼材，於加熱溫度：1030~1050℃下加熱後進行熱壓延，熱壓延後以自800℃至500℃之平均冷卻速度：3.0~4.0℃/秒之條件進行冷卻而獲得壓延材。又，自前述500℃放冷至室溫。其後，於下述所示之條件下酸洗，然後進行鉛浸漬而獲得線材。進而對於此線材，以下述所示條件進行酸洗及潤滑覆膜處理後，進行表2所示之抽線減面率之抽線，獲得No.1~12之直徑9.06mm之鋼線。且獲得No.13~16之直徑7.04mm之鋼線。 Melt steel materials that satisfy the composition shown in Table 1 below (the rest is iron and unavoidable impurities, and blank columns indicate no addition). Then use this steel material and heat-roll at heating temperature: 1030 ~ 1050 ℃, and then heat-roll at the average cooling rate from 800 ° C to 500 ° C: 3.0-4.0 ° C / s to obtain the rolling. material. In addition, it was allowed to cool to room temperature from the aforementioned 500 ° C. Thereafter, pickling was performed under the conditions shown below, and then lead immersion was performed to obtain a wire. Further, for this wire, pickling and lubricating film treatment were performed under the conditions shown below, and then a wire drawing with a drawdown reduction rate shown in Table 2 was performed to obtain a steel wire with a diameter of 9.06 mm in Nos. 1 to 12. A steel wire with a diameter of 7.04 mm was obtained from Nos. 13 to 16.
溶液：鹽酸 Solution: hydrochloric acid
濃度：20% Concentration: 20%
液溫：50℃ Liquid temperature: 50 ℃
浸漬時間：4~8分鐘 Dipping time: 4 ~ 8 minutes
覆膜種類：磷酸鹽覆膜 Coating type: phosphate coating
金屬皂(磷酸鹽處理劑(Bonderite)、潤滑劑(Bonder-Lube)處理)對覆膜層之浸漬時間：3~15分鐘 Immersion time of metal soap (phosphate treatment agent (Bonderite), lubricant (Bonder-Lube)) on the coating layer: 3 ~ 15 minutes
前述線材及鋼線之組織，係以可觀察與鉛浸漬後線材之壓延方向垂直之圓型斷面之方式切斷後，與後述螺栓之組織評價方法同樣地測定。其結果於任一例中，線材及鋼線之組織皆係滿足規定之面積率之肥粒鐵與波來鐵之2相組織。且，例如表2之No.3之線材及鋼線均係肥粒鐵面積率為64.7%，波來鐵面積率為35.2%，肥粒結晶粒度號為12.1號，且與使用該線材．鋼線所得之螺栓組織幾乎相同。其他任一例中，與上述No.3同樣，前述線材．鋼線之組織，經確認與螺栓之組織幾乎相同。另外，於表2及後述表3中，F表示肥粒鐵，P表示波來鐵，且F粒度表示肥粒鐵結晶粒度號。 The structure of the wire and the steel wire is cut in such a manner that a round cross-section perpendicular to the rolling direction of the wire after the lead immersion can be observed, and then measured in the same manner as the structure evaluation method of the bolt described later. As a result, in any of the examples, the structure of the wire rod and the steel wire is a two-phase structure of ferrous grain iron and boron iron that satisfy a predetermined area ratio. And, for example, the wire rod and steel wire of No. 3 in Table 2 both have a ferrous iron area ratio of 64.7%, a boiled iron area ratio of 35.2%, and a fertilizer grain crystalline particle size number of 12.1. The bolt structure obtained from steel wire is almost the same. In any other example, the wire is the same as the above No. 3. The structure of the steel wire is confirmed to be almost the same as that of the bolt. In Table 2 and Table 3 to be described later, F represents fertilized iron, P represents ferritic iron, and F particle size represents fertilized iron crystal grain size number.
使用上述鋼線，以夾持治具間隔：100mm，及十字頭速度：5mm/min為條件實施抗拉試驗，測定抗拉強度。其結果顯示於表2。 Using the steel wire, a tensile test was performed under the conditions of a clamping fixture interval: 100 mm and a crosshead speed: 5 mm / min, and the tensile strength was measured. The results are shown in Table 2.
對於上述鋼線，以下述條件進行冷壓造，於No.1~12，獲得M10及螺栓軸徑9.06mm之螺栓。且，於No.13~16，獲得M8及螺栓軸徑7.04mm之螺栓。而且，以肉眼觀察所得之螺栓輪緣部，確認有無裂縫。因此，無裂縫時評價為「冷壓造性優異」，有裂縫發生時評價為「冷壓造性差」。其結果顯示於表2。 The steel wire was cold-formed under the following conditions, and bolts with M10 and a bolt shaft diameter of 9.06 mm were obtained at Nos. 1 to 12. In addition, at Nos. 13 to 16, M8 and bolts with a shaft diameter of 7.04 mm were obtained. In addition, the obtained bolt rim portion was observed with the naked eye to confirm the presence or absence of cracks. Therefore, it was evaluated as "excellent cold pressability" when no cracks were found, and it was evaluated as "poor cold pressability" when cracks occurred. The results are shown in Table 2.
壓造裝置：阪村機械製作所製NBP550 Pressing device: NBP550 manufactured by Sakamura Machinery Co., Ltd.
壓造段數：第1段為頭部1次成型，第2段為頭部2次成型，第3段為頭部3次成型，合計3段 Number of stamped sections: the first section is the first molding of the head, the second section is the second molding of the head, and the third section is the third molding of the head, totaling 3 sections
壓造速度：1個/秒 Compression speed: 1 / second
對於所得之螺栓，於No.2、4、6及8，係如表3所示，進行鋅鍍敷處理作為表面處理，隨後以下述所示條件進行烘烤處理；於No.10、No.14及No.16，不進行鋅鍍敷處理而進行烘烤處理。No.1和No.2、No.3和No.4、No.5和No.6、No.7和No.8、No.9和No.10、No.13和No.14、及No.15和No.16之各組，係於製造步驟中，分別使用鋼材A、B、C、D、E、G及H，螺栓壓造之前以同一條件製造，螺栓壓造後之鍍敷-烘烤處理之有無不同之例。 The obtained bolts were subjected to zinc plating as a surface treatment at No. 2, 4, 6 and 8 as shown in Table 3, followed by baking treatment under the conditions shown below; at No. 10, No. 14 and No. 16, baking treatment was performed without performing zinc plating treatment. No. 1 and No. 2, No. 3 and No. 4, No. 5 and No. 6, No. 7 and No. 8, No. 9 and No. 10, No. 13 and No. 14, and No. The groups of .15 and No.16 are in the manufacturing steps, using steels A, B, C, D, E, G, and H, respectively, and manufactured under the same conditions before bolt pressing, and plating after bolt pressing- Is there any difference in the baking process?
處理溫度：195℃ Processing temperature: 195 ℃
處理時間：4小時 Processing time: 4 hours
次數：1次 Number of times: 1
No.1、3、5、7、9、11、12、13及15係使用僅經冷壓造之螺栓，No.2、4、6、8、10、14及16係使用上述鍍敷處理及/或烘烤處理後之螺栓，以下述方法進行組織觀察，同時評價其機械特性及抗延遲破壞性。 No. 1, 3, 5, 7, 9, 11, 12, 13 and 15 series use only cold-pressed bolts, and No. 2, 4, 6, 8, 10, 14 and 16 series use the above-mentioned plating treatment And / or the bolt after the baking treatment, the structure is observed by the following method, and the mechanical properties and resistance to delayed damage are evaluated at the same time.
作為螺栓之組織，如以下所述測定肥粒鐵之面積率、波來鐵之面積率及肥粒鐵結晶粒度號。其結果顯示於表3。 As the structure of the bolt, the area ratio of ferrous iron, the area ratio of boron iron, and the grain size number of ferrous iron were measured as described below. The results are shown in Table 3.
於螺栓之螺紋部，於垂直螺栓軸部之軸方向斷面切斷後，以硝酸醇溶液腐蝕後，以光學顯微鏡於倍率400倍下4視野觀察D/4位置(視野面積：0.08mm2)，進行圖像解析而測定肥粒鐵之面積率。前述圖像解析，係使用解析軟體粒子解析III(住友金屬科技股份公司製)。此外，肥粒鐵結晶粒度號，係依照比較法與標準樣品比較求得。 Cut off the threaded part of the bolt in the axial direction of the vertical bolt shaft, and then etch it with a nitric acid solution, then observe the D / 4 position in 4 fields under a magnification of 400 times with an optical microscope (field of view: 0.08mm 2 ) Image analysis was performed to measure the area ratio of ferrous iron. The aforementioned image analysis is performed using analysis software particle analysis III (manufactured by Sumitomo Metal Technology Co., Ltd.). In addition, the grain size number of the ferrous grain iron is obtained by comparison with a standard sample according to a comparison method.
波來鐵之面積率，係自100%減去肥粒鐵面積率求得。 The area ratio of boron iron is obtained by subtracting the area ratio of ferrous iron from 100%.
本發明實施形態之製造方法，由於鉛浸漬後 不再加熱至沃斯田鐵區域，故其肥粒鐵之面積率、肥粒鐵結晶粒度號、及波來鐵之面積率，於鉛浸漬後線材、鋼線及螺栓中幾乎相等。此外，表3中No.1、13、15及10之螺栓之組織結果，以及No.9之肥粒鐵結晶粒度號雖皆為「-」，該等結果認為分別與對No.1、No.13及No.15之各螺栓實施鍍敷及/或烘烤處理而得之No.2、No.14及No.16，對No.10之螺栓實施烘烤處理前之No.9，以及對No.9之螺栓實施烘烤處理而得之No.10幾乎相同。 According to the manufacturing method of the embodiment of the present invention, It is no longer heated to the Vostian iron area, so its area ratio of ferrous iron, grain size number of ferrous iron, and area ratio of boron iron are almost equal in lead, steel wire and bolt after lead impregnation. In addition, although the organization results of the bolts of No. 1, 13, 15, and 10 in Table 3, and the grain size of the iron grains of No. 9 are "-", these results are considered to be different from those of No. 1, No. 1, respectively. .13 and No.15 are bolts No.2, No.14 and No.16 obtained by plating and / or baking treatment, No.9 bolt No.9 before baking treatment, and The No. 10 obtained by baking the No. 9 bolt is almost the same.
螺栓之抗拉試驗係以遊隙螺紋長度：1.5×螺栓軸徑d及十字頭速度：5mm/min之條件實施，測定抗拉強度及強度，並求得強度比。其結果顯示於表3。 The tensile test of the bolt was performed under the conditions of the clearance thread length: 1.5 × bolt shaft diameter d and crosshead speed: 5 mm / min. The tensile strength and strength were measured, and the strength ratio was obtained. The results are shown in Table 3.
又，實施鍍敷-烘烤處理之發明例，即No.2、4、6及8中，螺栓之永久拉伸如下述測定。亦即，使上述各處理後之螺栓負荷保證荷重(9.8級M8螺栓：35500N，8.8級M10螺栓：21200N)15秒，測定移除荷重後之伸長度。進而，實施烘烤之以往例，及實施烘烤之發明例，即No.10、14及16，亦同樣測定永久伸長度。 Moreover, in the invention example which performed the plating-baking process, that is, in Nos. 2, 4, 6, and 8, the permanent tension of the bolt was measured as follows. That is, the guaranteed load of the bolt load after each of the above processes (9.8 M8 bolt: 35500N, 8.8 M10 bolt: 21200N) was measured for 15 seconds, and the elongation after the load was removed was measured. Furthermore, the conventional examples of baking and the invention examples of baking, namely, Nos. 10, 14, and 16, also measured the permanent elongation.
其結果，No.2為10.7μm、No.4為6.7μm、No.6為3.5μm、No.8為3.2μm、No.14為6.5μm、No.16為3.3μm，以往例的No.10為8.7μm。滿足JIS B1051(2014年)中規定之保證荷重時，較佳於該保證荷重試驗時之永久伸長度為12.5μm以下，但上述例係滿足此範圍。永久伸長度較佳為7μm以下，更佳為5μm以下。此外自該等例可知，No.4、6、8、14及16，雖於較發藍處理更低之溫度實施烘烤處理，但永久伸長度經充分抑制。 As a result, No. 2 was 10.7 μm, No. 4 was 6.7 μm, No. 6 was 3.5 μm, No. 8 was 3.2 μm, No. 14 was 6.5 μm, and No. 16 was 3.3 μm. 10 is 8.7 μm. Meet JIS At the guaranteed load specified in B1051 (2014), the permanent elongation is preferably 12.5 μm or less during the guaranteed load test, but the above examples satisfy this range. The permanent elongation is preferably 7 μm or less, and more preferably 5 μm or less. In addition, it can be known from these examples that although No. 4, 6, 8, 14, and 16 were subjected to baking treatment at a lower temperature than the bluing treatment, the permanent elongation was sufficiently suppressed.
對於一部分之螺栓評價抗延遲破壞性。其細節為，使用該螺栓，於36%鹽酸水溶液中浸漬30分鐘進行滲氫(hydrogen charging)後，以下述條件進行微速抗拉試驗，求出破裂伸長比，即[滲氫後螺栓之破裂伸長度]/[未經滲氫之破裂伸長度]。然後，螺栓軸徑為9.06mm之No.1~12，於上述破裂伸長比為0.80以上時評價為「螺栓具備必要之抗延遲破壞性」，上述破裂伸長比未達0.80時評價為「螺栓不具備必要之抗延遲破壞性」。另一方面，螺栓軸徑為7.04mm之No.13~16，於上述破裂伸長比為0.70以上時評價為「螺栓具備必要之抗延遲破壞性」，上述破裂伸長比未達0.70時評價為「螺栓不具備必要之抗延遲破壞性」。其結果，No.2為0.95，No.4為0.98，No.6為1.00，No.8為0.94，No.14為0.72，No.15為0.87，No.16為0.89，各螺栓皆具備必要之抗延遲破壞性。 A part of the bolts was evaluated for delayed destructiveness. The details are as follows: using the bolt, immersed in a 36% hydrochloric acid aqueous solution for 30 minutes for hydrogen charging, and performing a micro speed tensile test under the following conditions to determine the breaking elongation ratio, which is [the breaking elongation of the bolt after hydrogen permeation] Degree] / [Elongation at Break without Hydrogen Permeation]. Then, Nos. 1 to 12 with a bolt shaft diameter of 9.06 mm were evaluated as "the bolt has the necessary resistance to delayed fracture" when the fracture elongation ratio was 0.80 or more. When the fracture elongation ratio was less than 0.80, it was evaluated as "bolt failure." With the necessary resistance to delay destructive. " On the other hand, Nos. 13 to 16 of the bolt shaft diameter of 7.04 mm were evaluated as "the bolt has the necessary delayed fracture resistance" when the fracture elongation ratio was 0.70 or more, and evaluated as "the bolt elongation ratio did not reach 0.70". Bolts do not have the necessary resistance to delayed damage. " As a result, No. 2 is 0.95, No. 4 is 0.98, No. 6 is 1.00, No. 8 is 0.94, No. 14 is 0.72, No. 15 is 0.87, and No. 16 is 0.89. All bolts are necessary. Resistant to destructive delays.
十字頭速度：0.01mm/min Cross head speed: 0.01mm / min
遊隙螺紋長度：1.5d Clearance thread length: 1.5d
由該等結果可探討如下。No.1~8及No.13~16係滿足本發明實施形態中規定要件之發明例，本發明之實施形態之鋼線顯示優異之冷壓造性，且由所得之螺栓可知，即使不進行發藍處理等之高溫熱處理，亦顯示與必須經過發藍處理之以往例的No.10相近等級之高強度及強度比，且亦兼備抗延遲破壞性。尤其，No.14及No.16係兼具期望強度與減低永久伸長度之優異非熱處理螺栓。 These results can be explored as follows. Nos. 1 to 8 and Nos. 13 to 16 are examples of the invention satisfying the requirements specified in the embodiment of the present invention. The steel wire of the embodiment of the present invention exhibits excellent cold pressability, and it can be known from the obtained bolts that even if not performed, High-temperature heat treatment such as bluing treatment also shows high strength and strength ratio similar to No. 10 of the conventional example that must be bluing, and also has resistance to delayed damage. In particular, No. 14 and No. 16 are excellent non-heat-treated bolts having both desired strength and reduced permanent elongation.
相對於此，No.9、11及12為未滿足本發明之實施形態中規定之任一要件之例，其特性皆劣化。即，No.9由於C量過剩，熱壓延前之加熱時未固溶碳化物大量殘留，無法確保充分之肥粒鐵，強度比變小。No.11係添加本發明之實施形態中不積極使用之V及Nb之例。如 此於添加V及Nb時，雖可確保特性，但於製造階段中析出物形態之控制等變得不容易。且No.12係剛材之成分組成及組織於規定範圍之外，於經藍化處理等熱處理，亦無法獲得期望強度比之比較例。 In contrast, Nos. 9, 11, and 12 are examples in which any of the requirements specified in the embodiment of the present invention is not satisfied, and their characteristics are deteriorated. That is, No. 9 had an excessive amount of C, and a large amount of undissolved carbides remained during heating before hot rolling, so that sufficient ferrous iron could not be secured, and the strength ratio became small. No. 11 is an example of adding V and Nb which are not actively used in the embodiment of the present invention. Such as When V and Nb are added, the characteristics are ensured, but it is not easy to control the form of precipitates during the manufacturing stage. In addition, the composition and structure of No. 12 rigid materials are outside the specified range, and a comparative example of the desired strength ratio cannot be obtained by heat treatment such as blue treatment.
本申請同時主張以申請日為2016年3月31日之日本專利申請案特願第2016-071429號，及申請日為2017年2月24日之日本專利申請案特願第2017-033373號為基本申請之優先權。日本特願第2016-071429號及日本特願第2017-033373號藉由參照而併入本說明書。 This application also claims Japanese Patent Application No. 2016-071429 with a filing date of March 31, 2016, and Japanese Patent Application No. 2017-033373 with a filing date of February 24, 2017. Basic application priority. Japanese Patent Application No. 2016-071429 and Japanese Patent Application No. 2017-033373 are incorporated herein by reference.
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