JP2006169637A - Method for manufacturing high-strength carburized part - Google Patents
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本発明は、機械構造用鋼からなる部品、例えば、ギヤ、ＣＶＪなどの高強度化が要求される自動車用の浸炭部品に関する。 The present invention relates to carburized parts for automobiles that require high strength, such as parts made of steel for machine structural use, such as gears and CVJs.
ギヤ、ＣＶＪなどの自動車用部品では、小型軽量化に伴う高強度化が要求される。そこで、１）ＳＮＣＭなどのＮｉ鋼のように合金元素を添加して高強度化を図っている。しかし、このように合金元素を添加して高強度化を図った場合、素材コストが高くなり、冷間加工性が劣るために冷間鍛造ができず、さらに熱間鍛造後そのままでは切削できないので焼鈍などの熱処理が必要となるなどの問題がある。 Automotive parts such as gears and CVJs are required to have high strength as they are reduced in size and weight. Therefore, 1) alloying elements are added to increase the strength like Ni steel such as SNCM. However, when alloying elements are added in this way to increase the strength, the material cost increases, and cold workability cannot be achieved due to poor cold workability. There is a problem that a heat treatment such as annealing is required.
２）さらに浸炭後、再焼入れを行って結晶粒の微細化を図って高強度化している。しかし、この場合も、例えば、ＳＣＭなどの一般鋼を使用した場合では、結晶粒の微細化に限界があり十分な高強度化ができない問題がある。 2) Further, after carburizing, re-quenching is performed to refine crystal grains and increase the strength. However, also in this case, for example, when general steel such as SCM is used, there is a problem in that sufficient refinement cannot be achieved because there is a limit to refinement of crystal grains.
３）あるいは、加工処理により結晶粒の微細化を図って高強度化している。しかしこの場合も、成形と熱処理を組み合わせるため、成形の難しいものには適用できないなど部品形状が限定されるなどの問題がある。 3) Alternatively, the crystal grains are refined by processing to increase the strength. However, in this case as well, there is a problem that the shape of the part is limited because it cannot be applied to a difficult-to-mold product because the molding and heat treatment are combined.
また、浸炭時のγ粒の粗大化を防ぐものが出願され開示されている（例えば、特許文献１参照。）。 Further, an application for preventing coarsening of γ grains during carburizing has been filed and disclosed (for example, see Patent Document 1).
本発明が解決しようとする課題は、従来の上記の問題点を解消することであり、浸炭後再焼入れにより、積極的に旧オーステナイト粒を超微細化して強度を向上させることを目的とする。 The problem to be solved by the present invention is to solve the above-mentioned conventional problems, and an object is to positively refine ultrafine austenite grains and improve the strength by re-quenching after carburizing.
課題を解決するための本発明の手段は、請求項１の発明では、肌焼鋼からなる鋼部品を浸炭し高強度浸炭部品を得る方法において、質量％で、Ｃ：０．１０〜０．３５％、Ｓｉ：０．０３〜０．５０％、Ｍｎ：２．０％以下、Ｎ：０．０２０％以下、Ａｌ：０．００５〜０．０５％を含有し、さらに、Ｔｉ：０．０５〜０．２％、Ｖ：０．０２〜０．１０％、Ｎｂ：０．０２〜０．１０％のうち１種又は２種以上を含有し、残部Ｆｅおよび不可避不純物からなる肌焼鋼から形成の部品を、浸炭後、再焼入を行うことを特徴とする高強度浸炭部品の製造方法である。 The means of the present invention for solving the problem is that, in the invention of claim 1, in a method of carburizing a steel part made of case-hardened steel to obtain a high-strength carburized part, C: 0.10-0. 35%, Si: 0.03 to 0.50%, Mn: 2.0% or less, N: 0.020% or less, Al: 0.005 to 0.05%, and Ti: 0.005%. Case-hardened steel containing one or more of 05-0.2%, V: 0.02-0.10%, Nb: 0.02-0.10%, the balance being Fe and inevitable impurities This is a method for producing a high-strength carburized part, characterized in that the part formed from is re-quenched after carburizing.
請求項２の発明では、請求項１の手段の鋼成分に、さらに、質量％で、Ｃｒ：２．０％以下、Ｍｏ：２．０％以下、Ｎｉ：３．０％以下のうち１種又は２種以上を含有し、残部Ｆｅおよび不可避不純物からなる肌焼鋼から形成の部品を、浸炭後、再焼入を行うことを特徴とする高強度浸炭部品の製造方法である。 In the invention of claim 2, the steel component of the means of claim 1 is further added in mass%, Cr: 2.0% or less, Mo: 2.0% or less, Ni: 3.0% or less. Or it is a manufacturing method of the high-strength carburized part characterized by performing re-quenching after carburizing the part formed from the case-hardening steel which contains 2 or more types, and consists of remainder Fe and an inevitable impurity.
請求項３の発明では、請求項１または２の手段の鋼成分に、さらに、質量％で、Ｂ：０．０００５〜０．００５％を含有し、残部Ｆｅおよび不可避不純物からなる肌焼鋼から形成の部品を、浸炭後、再焼入を行うことを特徴とする高強度浸炭部品の製造方法である。 In the invention of claim 3, the steel component of the means of claim 1 or 2 further contains, in mass%, B: 0.0005 to 0.005%, and the case-hardened steel comprising the balance Fe and inevitable impurities. A method of manufacturing a high-strength carburized part, wherein the formed part is re-quenched after carburizing.
請求項４の発明では、請求項１〜３のいずれか１項の手段の鋼成分に、被削性改善のため、さらに、質量％で、Ｓ：０．０１〜０．２％、Ｐｂ：０．０１〜０．３％、Ｂｉ：０．０１〜０．３％、Ｔｅ：０．０１〜０．２％、Ｓｅ：０．０１〜０．２％、Ｃａ：０．０００３〜０．０１％から選択した１種ないし２種以上を含有し、残部Ｆｅおよび不可避不純物からなる肌焼鋼から形成の部品を、浸炭後、再焼入を行うことを特徴とする高強度浸炭部品の製造方法である。 In the invention of claim 4, in order to improve machinability, the steel component of the means of any one of claims 1 to 3 is further mass%, S: 0.01 to 0.2%, Pb: 0.01-0.3%, Bi: 0.01-0.3%, Te: 0.01-0.2%, Se: 0.01-0.2%, Ca: 0.0003-0. Manufacture of high-strength carburized parts characterized by re-hardening after carburizing parts formed from case-hardened steel containing one or more selected from 01% and the balance Fe and inevitable impurities Is the method.
請求項５の発明では、請求項１〜４のいずれか１項の手段の肌焼鋼から形成の部品を、浸炭後、再焼入れを行い、ＪＩＳ Ｇ０５５１ Ｎｏ．１１以上まで微細化したマルテンサイト組織からなる部品を得ることを特徴とする高強度浸炭部品の製造方法である。 In the invention of claim 5, the parts formed from the case-hardened steel of any one of claims 1 to 4 are carburized and then re-quenched, and JIS G0551 No. A method for producing a high-strength carburized component, characterized in that a component having a martensite structure refined to 11 or more is obtained.
本発明の手段における肌焼鋼に含有される鋼成分の限定理由を述べる。なお、％は質量％を示す。 The reasons for limiting the steel components contained in the case-hardened steel in the means of the present invention will be described. In addition,% shows the mass%.
Ｃ：Ｃは機械構造用部品として浸炭処理後の芯部強度を確保するために必要な元素であり、０．１０％未満ではその効果が十分に得られず、反対に０．３５％を超えると芯部の靱性を低下させる。そのため含有量を０．１０〜０．３５％とした。 C: C is an element necessary for securing the core strength after carburizing treatment as a machine structural component. If it is less than 0.10%, the effect cannot be sufficiently obtained, and conversely exceeds 0.35%. And reduce the toughness of the core. Therefore, the content was made 0.10 to 0.35%.
Ｓｉ：Ｓｉは０．０３％未満では脱酸効果が十分に得られず、０．５０％より過剰に含有させると加工性を低下させると共に浸炭時の粒界酸化層の形成を助長し、疲労特性についても低下させる。そのため含有量を０．０３〜０．５０％とした。 Si: If Si is less than 0.03%, a sufficient deoxidation effect cannot be obtained. If it is contained in excess of 0.50%, the workability is lowered and the formation of a grain boundary oxide layer during carburizing is promoted. The characteristics are also lowered. Therefore, the content is set to 0.03 to 0.50%.
Ｍｎ：Ｍｎは焼入性を確保するのに必要な元素であるが、２．０％を超えると加工性を低下させる。そのため、含有量を２．０％以下とした。 Mn: Mn is an element necessary for ensuring hardenability, but if it exceeds 2.0%, workability is lowered. Therefore, the content is made 2.0% or less.
Ｔｉ：Ｔｉは鋼中のｆｒｅｅ−Ｎを固定し、Ｂの焼入性への効果を向上させると共にＴｉ炭化物、Ｔｉを含有する複合炭化物、Ｔｉ窒化物を微細に析出させることによって、ＡｌＮに代って浸炭時のオーステナイト結晶粒度の粗大化を抑制するために必要な元素である。特に、鋼中に微細分散したナノオーダーのＴｉＣが結晶粒の成長を抑制する。Ｔｉが０．０５％未満ではその効果は十分でなく、０．１％を超えることが望ましい。しかし、０．２％を超えると析出物の量が過剰となり加工性を低下させる。そのため、Ｔｉは０．０５〜０．２％とした。 Ti: Ti fixes free-N in the steel, improves the effect on the hardenability of B, and finely precipitates Ti carbide, Ti-containing composite carbide, and Ti nitride to replace AlN. Thus, it is an element necessary for suppressing the coarsening of the austenite grain size during carburizing. In particular, nano-order TiC finely dispersed in steel suppresses the growth of crystal grains. If Ti is less than 0.05%, the effect is not sufficient, and it is desirable to exceed 0.1%. However, if it exceeds 0.2%, the amount of precipitates becomes excessive and the workability is lowered. Therefore, Ti is set to 0.05 to 0.2%.
Ｖ：Ｖは炭化物を形成し、Ｔｉ同様にオーステナイト結晶粒度の粗大化を抑制する効果がある。特に、鋼中に微細に分散したナノオーダーのＶＣが結晶粒の成長を抑制する。Ｖが０．０２％未満ではその硬化は得られず、０．１０％を超えて含有させると析出物の量が過剰となり加工性を低下させる。そのため、含有量を０．０２〜０．１０％とした。 V: V forms carbides and, like Ti, has the effect of suppressing coarsening of the austenite grain size. In particular, nano-order VC finely dispersed in steel suppresses the growth of crystal grains. If V is less than 0.02%, the curing cannot be obtained. If the content exceeds 0.10%, the amount of precipitates becomes excessive and the workability is lowered. Therefore, the content is set to 0.02 to 0.10%.
Ｎｂ：Ｎｂは炭化物あるいは窒化物を形成し、Ｔｉ同様にオーステナイト結晶粒度の粗大化を抑制する効果がある。特に、鋼中に微細に分散したナノオーダーのＮｂＣが結晶粒の成長を抑制する。Ｎｂが０．０２％未満ではその硬化は得られず、０．１０％を超えて含有させると析出物の量が過剰となり加工性を低下させる。そのため、含有量を０．０２〜０．１０％とした。なお、Ｔｉ、Ｖ、Ｎｂはそれらのうち１種または２種以上を含有することができる。 Nb: Nb forms carbides or nitrides, and has the effect of suppressing the coarsening of the austenite crystal grain size, similar to Ti. In particular, nano-order NbC finely dispersed in steel suppresses the growth of crystal grains. If Nb is less than 0.02%, the curing cannot be obtained. If Nb is contained in excess of 0.10%, the amount of precipitates becomes excessive and the workability is lowered. Therefore, the content is set to 0.02 to 0.10%. In addition, Ti, V, and Nb can contain 1 type, or 2 or more types among them.
Ｃｒ：Ｃｒは焼入性および浸炭性を向上させる元素であるが、２．０％を超えて含有させると浸炭層で粗大な炭化物を形成し、機械的性質、疲労特性を低下させる。そのため、含有量を２．０％以下とした。 Cr: Cr is an element that improves hardenability and carburization. However, if it is contained in an amount exceeding 2.0%, coarse carbides are formed in the carburized layer, and mechanical properties and fatigue characteristics are deteriorated. Therefore, the content is made 2.0% or less.
Ｍｏ：Ｍｏは焼入性および靱性を向上させる元素であるが、２．０％を超えて含有させると圧延あるいは鍛造後にベイナイトやマルテンサイト組織となり加工性を著しく低下させ、コストアップにつながる。そのため、含有量を２．０％以下とした。 Mo: Mo is an element that improves hardenability and toughness. However, if it is contained in excess of 2.0%, it becomes a bainite or martensite structure after rolling or forging, which significantly reduces workability and leads to an increase in cost. Therefore, the content is made 2.0% or less.
Ｎｉ：Ｎｉは焼入性および靱性を向上させる元素であるが、３．０％を超えて含有させると圧延あるいは鍛造後にベイナイトやマルテンサイト組織となり加工性を著しく低下させ、コストアップにつながる。そのため、含有量を３．０％以下とした。なお、Ｃｒ、Ｍｏ、Ｎｉはそれらのうち１種または２種以上を含有することができる。 Ni: Ni is an element that improves hardenability and toughness. However, if it is contained in an amount exceeding 3.0%, it becomes a bainite or martensite structure after rolling or forging, and the workability is remarkably reduced, leading to an increase in cost. Therefore, the content is made 3.0% or less. In addition, Cr, Mo, and Ni can contain 1 type, or 2 or more types among them.
Ｎ：Ｎは０．０１５％を超えて、殊に０．０２０％を超えて含有するとＴｉＮが増加し、疲労特性に悪影響を及ぼす。そのため、Ｎは０．０２０％以下とした。 N: If N exceeds 0.015%, particularly exceeding 0.020%, TiN increases and adversely affects fatigue properties. Therefore, N is set to 0.020% or less.
Ａｌ：Ａｌは脱酸剤として使用される元素であり、０．００５％未満ではその効果が十分でなく、０．０５％を超えるとアルミナ系酸化物が増加し疲労特性、加工性を低下させる。そのため、含有量を０．００５〜０．０５％とした。 Al: Al is an element used as a deoxidizer, and if it is less than 0.005%, its effect is not sufficient, and if it exceeds 0.05%, alumina-based oxides increase and fatigue characteristics and workability deteriorate. . Therefore, the content is set to 0.005 to 0.05%.
Ｂ：Ｂは極く微量の添加によって鋼の焼入性を著しく向上させる元素であり、任意に選択的に添加できる元素である。しかし、０．０００５％未満ではその効果は十分でなく、０．００５％を超えると逆に焼入性を低下させる。そのため、含有量を０．０００５〜０．００５％とした。 B: B is an element that remarkably improves the hardenability of steel by addition of a very small amount, and is an element that can be selectively added arbitrarily. However, if it is less than 0.0005%, the effect is not sufficient, and if it exceeds 0.005%, the hardenability is lowered. Therefore, the content is set to 0.0005 to 0.005%.
被削性の改善元素として、さらに、Ｓ：０．０１〜０．２％、Ｐｂ：０．０１〜０．３％、Ｂｉ：０．０１〜０．３％、Ｔｅ：０．０１〜０．２％、Ｓｅ：０．０１〜０．２％、Ｃａ：０．０００３〜０．０１％から選択した１種ないし２種以上を含有することができる。これらの元素は、その下限値以下では十分な被削性改善の効果はなく、その上限値を超えると逆に靱性を低下するので上限値以下とする。 As an element for improving machinability, S: 0.01 to 0.2%, Pb: 0.01 to 0.3%, Bi: 0.01 to 0.3%, Te: 0.01 to 0 0.2%, Se: 0.01 to 0.2%, Ca: 0.0003 to 0.01% selected from one or more. These elements do not have a sufficient machinability improvement effect below the lower limit value, and when the upper limit value is exceeded, the toughness decreases conversely.
本発明の作用について述べると、本発明においては鋼の強度を向上させるために、旧オーステナイト粒がＪＩＳ Ｇ０５５１で規定されているＮｏ．１１以上に極めて微細化したマルテンサイト組織の鋼を使用する。これによって鋼の破壊起点が粒界破壊から、粒内破壊へと移行し、曲げ強度、衝撃特性が向上する。 The action of the present invention will be described. In the present invention, in order to improve the strength of steel, the prior austenite grains are No. 1 defined in JIS G0551. A steel with a martensite structure that is extremely refined to 11 or more is used. As a result, the fracture start point of steel shifts from intergranular fracture to intragranular fracture, and the bending strength and impact characteristics are improved.
本発明の上記の鋼から形成の部品は、さらに浸炭後、再焼入れを行うことが特に重要であり、通常の浸炭焼入れのままでは、超微細化しない。すなわち、浸炭焼入れし、前組織をマルテンサイト（またはベイナイト）にした状態で焼入れすると超微細化する。 It is particularly important for the parts formed from the above steel of the present invention to be re-quenched after carburizing, and if the carburized and quenched as usual, it will not be ultrafine. That is, when carburizing and quenching and quenching in a state where the previous structure is martensite (or bainite), it becomes ultrafine.
ここでは、マルテンサイト（またはベイナイト）は再焼入れの加熱時にオーステナイトに一旦なるが、このオーステナイト生成サイトが多いため、いたるところからオーステナイト粒ができる。このオーステナイト粒を微細分散したＴｉＣがピンニングし、結晶粒の成長を止める。その状態から焼き入れされるため、超微細化したマルテンサイト組織ができる。 Here, martensite (or bainite) once becomes austenite at the time of re-quenching heating, but since there are many austenite generation sites, austenite grains are formed everywhere. TiC in which the austenite grains are finely dispersed is pinned to stop the growth of crystal grains. Since it is quenched from that state, an ultrafine martensite structure is formed.
すなわち、Ｔｉを添加した鋼（出願人の開発した鋼で、特開平１０−８１９３８号に開示の鋼）を旧オーステナイト結晶粒度がＪＩＳ Ｇ０５５１で規定されているＮｏ．１１以上まで微細化したマルテンサイト組織からなる鋼とし、この鋼からなる鋼部品に、特に、浸炭後、再焼入れすることにより、結晶粒が超微細化することを利用している。一般鋼（ＳＣＭなど）も再焼入れすることにより微細化するが、粒度Ｎｏ．１１未満程度が限界であり、また、混粒が発生し易い。 That is, a steel added with Ti (a steel developed by the applicant and disclosed in Japanese Patent Laid-Open No. 10-81938) is obtained from No. 1 in which the prior austenite grain size is defined by JIS G0551. The steel is made of a martensite structure refined to 11 or more, and the steel parts made of this steel are utilized, in particular, by re-quenching after carburizing, thereby refining crystal grains. General steel (such as SCM) is refined by re-quenching. Less than 11 is the limit, and mixed grains are likely to occur.
Ｔｉを添加した鋼の場合、特開平１０−８１９３８号に開示の発明では、上記のＳＣＭなどと同様に、結晶粒の粗大化は阻止されて高強度となっているが、粒度はＮｏ．１１未満程度である。これに対し、本発明における鋼では、旧オーステナイト結晶粒度がＪＩＳ Ｇ０５５１で規定されているＮｏ．１１以上まで微細化したマルテンサイト組織からなる鋼とし、このＴｉ添加の鋼からなる部品を、さらに浸炭後、再焼入れすることにより、ナノオーダーのＴｉＣが微細に分散し、結晶粒の成長を止める（ピンニング効果）。これにより一般鋼では達成できなかった領域の結晶粒度Ｎｏ．１１を超えて超微細化することが可能となり、この結晶粒の超微細化により、さらに高強度化が図れるものである。 In the case of steel added with Ti, in the invention disclosed in Japanese Patent Laid-Open No. 10-81938, as in the above SCM, the coarsening of the crystal grains is prevented and the strength is increased. It is less than 11. In contrast, in the steel according to the present invention, the old austenite grain size is No. defined in JIS G0551. Steel made of martensite structure refined to 11 or more, and parts made of Ti-added steel are further carburized and then re-quenched, so that nano-order TiC is finely dispersed and crystal grain growth is stopped. (Pinning effect). As a result, the grain size No. in the region that could not be achieved with general steel. It is possible to achieve ultrafineness exceeding 11, and it is possible to further increase the strength by making this crystal grain ultrafine.
これにより、Ｎｉなどの高価な元素を用いなくとも、機械的性質（曲げ強度、靱性など）を大幅に向上させることができる。また加工熱処理ではないので、全ての部品に適用できる。 Thereby, mechanical properties (bending strength, toughness, etc.) can be greatly improved without using expensive elements such as Ni. Since it is not a thermomechanical treatment, it can be applied to all parts.
以上説明したように、本発明は、Ｔｉを添加した鋼を、旧オーステナイト結晶粒度がＪＩＳ Ｇ０５５１で規定されているＮｏ．１１以上まで微細化したマルテンサイト組織からなる高強度肌焼鋼とし、さらにこの鋼から鋼部品とし、浸炭後、再焼入れをすることで、結晶粒度をＪＩＳ Ｇ０５５１ Ｎｏ．１１以上まで微細化したマルテンサイト組織からなるものが得られ、本発明は自動車用部品として従来にない高強度の浸炭部品を得るものとして優れた方法である。 As described above, according to the present invention, a steel to which Ti is added is used for No. in which the prior austenite grain size is defined by JIS G0551. A high-strength case-hardened steel having a martensite structure refined to 11 or more, and further steel steel parts made from this steel, and re-quenched after carburizing, the grain size of JIS G0551 No. What consists of the martensite structure refined | miniaturized to 11 or more is obtained, and this invention is an outstanding method as what obtains the high intensity | strength carburized component which is not conventionally as a component for motor vehicles.
本発明の請求項１〜４の実施の形態の鋼は、表１および表２の発明鋼のＮｏ．９〜３１に示す鋼組成で、旧オーステナイト粒度がＪＩＳ Ｇ０５５１で規定されているＮｏ．１１以上に極めて微細化したマルテンサイト組織の鋼からなる。発明鋼のＮｏ．９〜３１の鋼はナノオーダーのＴｉＣを微細分散したＴｉ添加の鋼である。請求項５の実施の形態の高強度浸炭部品の製造方法に係るものは、上記の鋼からなる鋼部品を、浸炭後、再焼入れして結晶粒をＪＩＳ Ｇ０５５１ Ｎｏ．１１以上まで微細化したマルテンサイト組織からなる部品としたものである。 The steels of the embodiments of claims 1 to 4 of the present invention are No. Nos. 9 to 31 with the old austenite grain size specified in JIS G0551. It consists of a steel with a martensite structure that is extremely refined to 11 or more. No. of invention steel. Steels 9 to 31 are Ti-added steels in which nano-order TiC is finely dispersed. According to the method for manufacturing a high-strength carburized part according to the embodiment of claim 5, the steel part made of the above steel is carburized and then re-quenched to obtain crystal grains according to JIS G0551 No. The part is made of a martensite structure refined to 11 or more.
表１および表２に示す比較鋼および発明鋼の供試材を１００ｋｇ真空溶解炉にて溶製してなる鋼片を１２５０℃に加熱してφ２０ｍｍの棒鋼に鍛伸した。この場合、微細なＴｉ炭化物を析出させるために、鋼片を１２５０〜１４００℃で圧延する。さらに棒あるいは線に圧延するときは、Ａｃ3〜１０５０℃で圧延する。次いで、９５０℃で仕上げ鍛伸して、さらにφ１４ｍｍ×２１ｍｍＨの円柱試験片に加工した後、９３０℃で６時間保持して浸炭焼入れした後、８５０℃で０．５時間保持して再焼入れし、１８０℃に１．５時間保持して焼戻しする。 Steel pieces formed by melting the test materials of comparative steel and invention steel shown in Tables 1 and 2 in a 100 kg vacuum melting furnace were heated to 1250 ° C. and forged into φ20 mm steel bars. In this case, the steel slab is rolled at 1250 to 1400 ° C. in order to precipitate fine Ti carbide. Further, when rolling into bars or wires, rolling is performed at Ac 3 to 1050 ° C. Next, after finishing and forging at 950 ° C., and processing into a cylindrical specimen of φ14 mm × 21 mmH, holding at 930 ° C. for 6 hours and carburizing and quenching, holding at 850 ° C. for 0.5 hours and re-quenching And tempering at 180 ° C. for 1.5 hours.
上記で得られた試験片の結晶粒をＪＩＳ ＧＯ５５１の規定により測定し、その結果を表３および表４に示す。本発明鋼のＮｏ．９〜３１は、比較鋼のＮｏ．１〜８に比し粒度Ｎｏ．は高く、いずれもＮｏ．１１以上で、結晶粒が超微粒であることがわかる。 The crystal grains of the test piece obtained above were measured according to JIS GO551, and the results are shown in Tables 3 and 4. No. of the steel of the present invention. Nos. 9 to 31 are comparative steel Nos. In comparison with 1-8, the particle size No. No. It can be seen that the grain size is 11 or more.
本発明に係る発明鋼Ｎｏ．１０からなる鋼部品と比較例に係る比較鋼Ｎｏ．３および比較鋼Ｎｏ．８からなる鋼部品の浸炭後の再焼入れした結晶粒径の４００倍で示す顕微鏡写真を図１に示す。発明鋼Ｎｏ．１０の結晶粒径が、比較鋼Ｎｏ．３および比較鋼Ｎｏ．８の結晶粒径に比して極めて微細であることがわかる。 Invention steel No. 1 according to the present invention. No. 10 steel part and comparative steel No. 3 and comparative steel no. FIG. 1 shows a photomicrograph taken at 400 times the re-quenched crystal grain size after carburization of a steel part consisting of eight. Invention Steel No. No. 10 crystal grain size is comparative steel no. 3 and comparative steel no. As can be seen from FIG.
さらに、亀裂発生荷重と破断荷重を評価するために、静的３点曲げ試験を行い、その結果を比較鋼Ｎｏ．１に対する比で表３に示す。静的３点曲げ試験は、浸炭後、再焼入れした角１０ｍｍ×長さ７０ｍｍの試験片に、２ｍｍＶノッチを設け、スパン間距離５０ｍｍで行った。本発明に係る鋼の供試材のＮｏ．９〜３１は、比較鋼の供試材のＮｏ．１〜８に比し初期亀裂発生荷重および亀裂発生荷重で優れており、特にＮｏ．１に比し２倍以上の初期亀裂発生荷重で優れていることが分かる。さらに発明鋼Ｎｏ．１０と比較鋼Ｎｏ．３の静曲げ試験の破壊起点部と伝播部のＳＥＭ写真を図２に示す。同図において、比較鋼Ｎｏ．３では起点部も伝播部も粒界破壊であるが、発明鋼Ｎｏ．１０では破壊起点が粒界破壊から、粒内破壊へ移行していることがわかる。 Furthermore, in order to evaluate the crack generation load and the fracture load, a static three-point bending test was performed. The ratio to 1 is shown in Table 3. The static three-point bending test was performed at a distance of 50 mm between spans by providing a 2 mmV notch on a test piece of 10 mm square × 70 mm length that was re-quenched after carburizing. No. of the steel specimen according to the present invention. Nos. 9 to 31 are Nos. Of specimens for comparison steel. The initial crack initiation load and crack initiation load are superior to those of Nos. 1-8. It can be seen that the initial crack generation load is more than twice that of 1. Furthermore, the invention steel No. 10 and comparative steel no. FIG. 2 shows SEM photographs of the fracture starting point and propagation part of the static bending test of No. 3. In FIG. In No. 3, both the starting part and the propagation part are grain boundary fractures. 10 indicates that the fracture starting point has shifted from intergranular fracture to intragranular fracture.
また、さらに衝撃値を評価するために、浸炭後、再焼入れした角１０ｍｍ×長さ５５ｍｍの試験片に、１０ＲＣ ２ｍｍノッチを設けて、シャルピー衝撃試験を行い、その結果を比較鋼Ｎｏ．１に対する比で表４に示す。本発明に係る鋼の供試材のＮｏ．９〜３１は、比較鋼の供試材のＮｏ．１〜８に比し格段に衝撃値で優れており、特にＮｏ．１に比し２倍以上の衝撃値で優れていることが分かる。 Further, in order to further evaluate the impact value, a Charpy impact test was performed by providing a 10RC 2 mm notch on a 10 mm square × 55 mm long test piece which had been re-quenched after carburizing. The ratio to 1 is shown in Table 4. No. of the steel specimen according to the present invention. Nos. 9 to 31 are Nos. Of specimens for comparison steel. Compared to 1-8, the impact value is far superior. It can be seen that the impact value is more than double that of 1.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009034970A1 (en) * | 2007-09-12 | 2009-03-19 | Sanyo Special Steel Co., Ltd. | Case-hardening steel being excellent in contact pressure fatigue strength, impact strength and bending fatigue strength |
| JP2010001527A (en) * | 2008-06-20 | 2010-01-07 | Daido Steel Co Ltd | Gear component |
| EP3591081A1 (en) * | 2018-07-05 | 2020-01-08 | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Use of a steel for producing a steel component, namely for a gearwheel, a shaft, an axle or a tool holder to a thermochemically cured edge layer and such steel component having a thermochemically cured edge layer |
| KR20200075456A (en) * | 2018-12-18 | 2020-06-26 | 주식회사 포스코 | High carbon boron added steel and manufacturing method thereof |
| CN111394652A (en) * | 2020-04-09 | 2020-07-10 | 钢铁研究总院淮安有限公司 | Rare earth armor steel and manufacturing method thereof |
| CN115505841A (en) * | 2022-08-31 | 2022-12-23 | 马鞍山钢铁股份有限公司 | Fatigue-carburization-resistant gear steel with excellent tail end hardenability and manufacturing method thereof |
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2006
- 2006-01-04 JP JP2006000281A patent/JP2006169637A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009034970A1 (en) * | 2007-09-12 | 2009-03-19 | Sanyo Special Steel Co., Ltd. | Case-hardening steel being excellent in contact pressure fatigue strength, impact strength and bending fatigue strength |
| JP2009068064A (en) * | 2007-09-12 | 2009-04-02 | Sanyo Special Steel Co Ltd | Case hardening steel excellent in bearing fatigue-strength, impact-strength and bending fatigue-strength |
| JP2010001527A (en) * | 2008-06-20 | 2010-01-07 | Daido Steel Co Ltd | Gear component |
| EP3591081A1 (en) * | 2018-07-05 | 2020-01-08 | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Use of a steel for producing a steel component, namely for a gearwheel, a shaft, an axle or a tool holder to a thermochemically cured edge layer and such steel component having a thermochemically cured edge layer |
| KR20200075456A (en) * | 2018-12-18 | 2020-06-26 | 주식회사 포스코 | High carbon boron added steel and manufacturing method thereof |
| KR102153196B1 (en) | 2018-12-18 | 2020-09-07 | 주식회사 포스코 | High carbon boron added steel and manufacturing method thereof |
| CN111394652A (en) * | 2020-04-09 | 2020-07-10 | 钢铁研究总院淮安有限公司 | Rare earth armor steel and manufacturing method thereof |
| CN115505841A (en) * | 2022-08-31 | 2022-12-23 | 马鞍山钢铁股份有限公司 | Fatigue-carburization-resistant gear steel with excellent tail end hardenability and manufacturing method thereof |
| CN115505841B (en) * | 2022-08-31 | 2024-01-19 | 马鞍山钢铁股份有限公司 | Fatigue-resistant carburized gear steel with excellent end hardenability and manufacturing method thereof |
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