JPS6369918A - Manufacture of high strength rail having superior toughness - Google Patents
Manufacture of high strength rail having superior toughnessInfo
- Publication number
- JPS6369918A JPS6369918A JP21146286A JP21146286A JPS6369918A JP S6369918 A JPS6369918 A JP S6369918A JP 21146286 A JP21146286 A JP 21146286A JP 21146286 A JP21146286 A JP 21146286A JP S6369918 A JPS6369918 A JP S6369918A
- Authority
- JP
- Japan
- Prior art keywords
- rail
- toughness
- steel
- austenite
- strength
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 22
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 8
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 238000010438 heat treatment Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 8
- 238000005098 hot rolling Methods 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 abstract description 40
- 239000010959 steel Substances 0.000 abstract description 40
- 238000007670 refining Methods 0.000 abstract description 8
- 229910000851 Alloy steel Inorganic materials 0.000 abstract 1
- 229910001562 pearlite Inorganic materials 0.000 description 15
- 230000000694 effects Effects 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005096 rolling process Methods 0.000 description 7
- 229910001567 cementite Inorganic materials 0.000 description 6
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 6
- 230000009466 transformation Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 238000003303 reheating Methods 0.000 description 5
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 239000010953 base metal Substances 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000004881 precipitation hardening Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 206010053759 Growth retardation Diseases 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野コ
本発明は、レールの基本的な特性である耐摩耗性および
耐損傷性に加えて、寒冷地での靭性を確保し、溶接性に
もすぐれた高強度レールの製造法に関するもので、耐食
性の大幅な改善も期待出来る。[Detailed Description of the Invention] [Industrial Field of Application] In addition to the wear resistance and damage resistance, which are the basic characteristics of rails, the present invention ensures toughness in cold regions and improves weldability. This relates to an excellent method for manufacturing high-strength rails, and is expected to significantly improve corrosion resistance.
［従来の技術］
近年、海外の鉱山鉄道用レールの歴史は、積載重量の増
加とあいまって、高強度化の一途をたどって来た。しか
し、ここに至って、列車燃費向上の観点からレール塗油
が本格的に採り入れられるようになり、塗油によってレ
ールの摩耗が抑制されるものの本来摩耗によって取り去
られるはずのレール表面の疲労層から表面損傷が発生す
るようになり、新たな問題が生じて来た。この対策とし
ては、特願昭６０−１９６９８０号公報に示したような
、潤滑条件下でもある程度摩耗が進行することを狙った
従来より硬度を低めとした高強度レールがある。そして
、レール敷設現場での対策としては、レール表面に蓄積
した疲労層を定期的にかつ望ましいレール形状に削正す
るレール削正車を走らせている。[Prior Art] In recent years, the history of overseas mining railway rails has been one of increasing strength as the loading weight has increased. However, at this point, rail lubrication has been adopted in earnest from the perspective of improving train fuel efficiency, and although lubrication suppresses rail wear, the fatigue layer on the rail surface that would normally be removed by abrasion has been removed from the surface. Damage began to occur and new problems arose. As a countermeasure against this problem, there is a high-strength rail with a lower hardness than conventional rails, which aims at allowing wear to progress to some extent even under lubricated conditions, as shown in Japanese Patent Application No. 196980/1980. As a countermeasure at the rail installation site, a rail grinding vehicle is run to regularly grind away the fatigue layer that has accumulated on the rail surface into the desired rail shape.
しかし、一方では、海外鉱山鉄道での輸送の効率化のた
めに、さらに一層の高積載重量化が検討されており、安
価な高強度レールの製造が要求されている。同時に高荷
重化、高強度化を背景としたレール靭性の改善も重要な
課題であり、特にカナダやソ連のような寒冷地では、靭
性のすぐれた高強度レールの製造が望まれている。However, on the other hand, in order to improve the efficiency of transportation on overseas mining railways, even higher loading weights are being considered, and there is a demand for the production of inexpensive high-strength rails. At the same time, improving the toughness of rails is an important issue in response to higher loads and higher strength.Especially in cold regions such as Canada and the Soviet Union, there is a desire to manufacture high-strength rails with excellent toughness.
［発明が解決しようとする問題点］
従来の高強度レールは１例えば特開昭５５〜１２５２３
１号公報はｒＣ： ０．５５〜０．８０％。[Problems to be solved by the invention] Conventional high-strength rails include 1, for example, Japanese Patent Application Laid-Open No. 1983-12523.
Publication No. 1 has rC: 0.55 to 0.80%.
Ｓｉ：０．５〜１．２０％、Ｍｎ： ０．８〜１．５％
。Si: 0.5-1.20%, Mn: 0.8-1.5%
.
Ａ Ｑ ： ０．００５〜０．０５％あるいはさらにｃ
ｒ：０．２０〜０．９０％、Ｎｂ： ０．００４〜０．
０１０％を含有する溶接性低合金熱処理レール」、特開
昭５７−１９８２１６号公報はｒＣ： ０．６０〜０．
８５％、Ｓｉ： ０．１〜０．８％、Ｍｎ：０．７０〜
１．５％、Ｃｒ： ０．２〜０．８％あるいはさらにＮ
ｂ、’Ｊ、Ｔｉの少量を選択添加した高強度レール」な
とのように１強度１２０級の高強度レールの溶接性付与
には相当量のＣｒの添加が特徴的に行われている。AQ: 0.005-0.05% or even c
r: 0.20-0.90%, Nb: 0.004-0.
"Weldable Low Alloy Heat Treated Rail Containing 0.10%", JP-A-57-198216, has rC: 0.60-0.
85%, Si: 0.1~0.8%, Mn: 0.70~
1.5%, Cr: 0.2-0.8% or further N
A considerable amount of Cr is characteristically added to impart weldability to high-strength rails with a strength of 120 grade, such as ``high-strength rails with selectively added small amounts of J and Ti''.
高強度レールの溶接性とは、通常の溶接条件で特殊な前
後熱処理を必要とすることなく、母材レールと一体とな
る継手硬度を有することであり。The weldability of a high-strength rail means that it has a joint hardness that allows it to become integrated with the base metal rail under normal welding conditions without the need for special heat treatment before and after.
継手部の局部的な摩耗を阻止することは、列車の衝撃的
なレールへの負荷を妨げ間接的なレール靭性確保に重要
な役割を果す。Preventing localized wear on joints plays an important role in indirectly ensuring rail toughness by preventing trains from applying impactful loads to the rails.
また、レール鋼へのＣｒの添加はパーライト組織中のセ
メンタイト強化を通して、耐摩耗性に貢献する一方、衝
撃的な応力に対しては、逆にセメンタイトの脆化をもた
らし靭性を損う方向に作用する。Additionally, while the addition of Cr to rail steel contributes to wear resistance by strengthening the cementite in the pearlite structure, it also acts in the direction of embrittling the cementite and impairing toughness in response to impact stress. do.
［問題点を解決するための手段］
本発明は上記のごとき問題点を解決するために、Ｃｒの
代替としてＣｕ添加によるレール鋼の高強度化と、Ｎ
ｉ ｇ加による靭性の改善を果そうとするもノテあル、
ソノ要旨は、Ｃ： ０．５５〜０．８５％、Ｓｉ： ０
．２０〜１．２０％、Ｍｎ： ０．５〜１゜６５％、Ｃ
ｒ： ０．１〜０．１９％、Ｃｕ：０．２〜１．０％、
Ｎｉ： ０．２〜１．０％で、あるいはさら４、ニーＮ
ｂ： ０．００５〜０．０５％、 Ｖ ： ０．０２〜
０゜２０％、Ｔｉ： ０．０１〜０．０５％、Ａｌ：０
．００５〜０．０５％の１種又は２種以上を含有し、残
部が鉄および不可避的不純物からなるレールの頭部を、
熱間圧延終了後あるいは熱処理する目的で加熱されたオ
ーステナイト域温度からの冷却において、８００〜５０
０℃間を冷却速度２〜５℃／ｓｅｃで急速冷却すること
を特徴とする靭性に優れた高強度レールの製造法である
。[Means for Solving the Problems] In order to solve the above problems, the present invention aims to increase the strength of rail steel by adding Cu as a substitute for Cr, and to increase the strength of rail steel by adding Cu as a substitute for Cr.
Attempts to improve toughness by adding i.g.
Sono summary: C: 0.55-0.85%, Si: 0
．． 20~1.20%, Mn: 0.5~1°65%, C
r: 0.1-0.19%, Cu: 0.2-1.0%,
Ni: 0.2 to 1.0% or even 4, Ni N
b: 0.005~0.05%, V: 0.02~
0°20%, Ti: 0.01-0.05%, Al: 0
．． 0.005 to 0.05% of one or more kinds, with the remainder consisting of iron and unavoidable impurities,
800 to 50 during cooling from the austenite region temperature heated after hot rolling or for the purpose of heat treatment.
This is a method for manufacturing a high-strength rail with excellent toughness, characterized by rapid cooling between 0°C and a cooling rate of 2 to 5°C/sec.
［作用］ 以下本発明について詳細に説明する。[Effect] The present invention will be explained in detail below.
先ずレールの成分組成を上記のように定めた限定理由に
ついて説明する。First, the reason for limiting the composition of the rail as described above will be explained.
Ｃは高強度化およびパーライト組織生成のための必須元
素であり、また耐摩耗性に対して一義的に効果を示す元
素であるが、０．５５％未満ではオーステナイト粒界に
耐摩耗性および耐損傷性に好ましくない初析フェライト
が多址に生成し、０゜８５％を超えるとオーステナイト
粒界に有害な初析セメンタイトを生成させるばかりか、
熱処理層や溶接部の微小偏析部にマルテンサイトが生成
し、靭性を損うため０．５５〜０．８５％に限定した。C is an essential element for high strength and pearlite structure formation, and is also an element that has a unique effect on wear resistance, but if it is less than 0.55%, it causes wear resistance and wear resistance at austenite grain boundaries. A large amount of pro-eutectoid ferrite, which is unfavorable for damage properties, is generated, and if it exceeds 0°85%, it not only produces pro-eutectoid cementite that is harmful to the austenite grain boundaries.
Martensite is generated in micro-segregation areas of heat-treated layers and welded parts, impairing toughness, so the content is limited to 0.55 to 0.85%.
Ｓｉはパーライト組織中のフェライトへの固溶体硬化に
よる高強度化に寄与するばかりか、わずかばかりである
がレール鋼の靭性改善にも貢献する。Si not only contributes to high strength through solid solution hardening of ferrite in the pearlite structure, but also contributes to improving the toughness of rail steel, albeit only slightly.
Ｓｉは脱酸元素として０．２％以上の添加が必要であり
、また１、２０％を超えると脆化をもたらし溶接接合性
をも減するので０．２〜１．２０％に限定した。Si needs to be added in an amount of 0.2% or more as a deoxidizing element, and if it exceeds 1.20%, it causes embrittlement and reduces weld bondability, so it is limited to 0.2 to 1.20%.
ＭｎはＣ同様パーライト変態温度を低下させ焼入性を高
めることによって、高強度化に寄与する元素である。し
かし、０．５％未満ではその寄与が小さくまた１、５０
％を超ると偏祈部にマルテンサイトを生成させやすくす
るため０．５０〜１゜５０％に限定した。Ｃｒはパーラ
イト変態開始温度を低下させ高強度化に寄与すると共に
、パーライト中のセメンタイトを強化することによって
も耐摩耗性向上に貢献するが一方ではセメンタイトの衝
撃靭性を低下させる作用をもたらす。しかし、Ｃｒのセ
メンタイト強化作用は捨てがたく、さらに溶接継半部軟
化防止の観点からも、微量のＣｒ添加は望まれるところ
である。そこで強度に一定の寄与をし、かつ靭性を損わ
ない添加量として０゜１％〜０．１９％のＣｒに限定し
た。Ｃｒ添加量の上限を０．１９％に限定した理由は、
これ以上でｊ±靭性を損うが、これ以下で十分に耐摩耗
性が発揮され、塑性変形によってもたらされるセメンタ
イトからの割れの発生を防止することが出来る。Like C, Mn is an element that contributes to high strength by lowering the pearlite transformation temperature and increasing hardenability. However, if it is less than 0.5%, its contribution is small and 1.5%
If the content exceeds 0.50% to 1.5%, it is limited to 0.50% to 1.50% to facilitate the formation of martensite in the eccentric parts. Cr contributes to high strength by lowering the pearlite transformation start temperature, and also contributes to improving wear resistance by strengthening cementite in pearlite, but on the other hand, it has the effect of reducing the impact toughness of cementite. However, the cementite-strengthening effect of Cr cannot be ignored, and addition of a small amount of Cr is desired from the viewpoint of preventing softening of the weld joint. Therefore, the amount of Cr added is limited to 0.1% to 0.19%, which makes a certain contribution to strength and does not impair toughness. The reason why the upper limit of the amount of Cr added was limited to 0.19% is as follows.
If it is more than this, j± toughness will be impaired, but if it is less than this, sufficient wear resistance will be exhibited, and the occurrence of cracks from cementite caused by plastic deformation can be prevented.
Ｃｕは析出硬化元素として知られているが、０．６％未
満ではその効果はない。しかし、レール鋼におけるＣｕ
の強化機構を鋭意研究したところ、０゜６％未満でもパ
ーライト変態温度低下によるパーライト層間隔の微細化
を通して高強度化に寄与することが明らかとなった。し
かし０．２％未満のＣｕ添加ではその効果は小さく、１
．０％を超ると析出硬化量も一定となり意味をなさなく
なるため、０．２〜１．０％に限定した。一方Ｃｕの添
加は熱間脆性をもたらすことも良く知られており、レー
ル圧延初期にオーステナイト粒界に析出するＣｕにより
熱間での割れが生ずる。Although Cu is known as a precipitation hardening element, it has no effect if it is less than 0.6%. However, Cu in rail steel
As a result of intensive research on the strengthening mechanism of steel, it was found that even if it is less than 0.6%, it contributes to high strength through the refinement of the pearlite layer spacing due to the decrease in the pearlite transformation temperature. However, the effect is small when Cu is added less than 0.2%, and 1
．． If it exceeds 0%, the amount of precipitation hardening becomes constant and becomes meaningless, so it is limited to 0.2 to 1.0%. On the other hand, it is well known that the addition of Cu causes hot brittleness, and hot cracking occurs due to Cu precipitated at austenite grain boundaries in the initial stage of rail rolling.
このような熱間脆性の防止法としてＮｉの添加を行った
ａＮｘはＣｕと同旦もしくはその２／３程度の添加によ
ってオーステナイト中でのＣｕの固溶量を高め、熱間で
のＣｕの析出を抑制することで熱間脆性を防止できる。As a method to prevent hot embrittlement, Ni is added to aNx at the same time as Cu or at about 2/3 of the amount to increase the solid solution amount of Cu in austenite and prevent Cu precipitation during hot heating. By suppressing this, hot embrittlement can be prevented.
またＮｉの添加によってレール鋼の靭性改善も果すこと
が出来る。しがしＮｉの０．２％未満の添加では、その
効果は期待出来ず、１．０％以上の添加ではあまりに高
価となり経済性から現実性がない、そこでＮｉの添加量
を０．２〜１．０％とした。Furthermore, the toughness of rail steel can be improved by adding Ni. If less than 0.2% of Ni is added, no effect can be expected, and if more than 1.0% is added, it becomes too expensive and is not practical from an economic point of view. It was set at 1.0%.
さらに本発明では、必要によって上記の成分の他にＮｂ
ｅ Ｖ、Ｔｉ、Ａｐｔなどのオーステナイト粒細粒化元
素を添加することによって、レール鋼の靭性改善をより
一層安定なものとすることができる。Ｎｂは熱間圧延時
に低温加熱することによってＮｂ （Ｃ，Ｎ）の析出物
がオーステナイト粒成長を抑制し細粒化に寄与する。ま
た、高温加熱・低温仕上圧延によって熱間圧延後のオー
ステナイト粒を細粒化し、強制冷却後に得られるパーラ
イトブロックサイズを細粒化することによって靭性の改
善が図られる。このとき有効な下限Ｎｂ添加量は０．０
０５％であり、０．０５％を超えると粗大なＮｂＣが生
成し、かえって脆化をもたらす。Furthermore, in the present invention, in addition to the above components, Nb
By adding an austenite grain refining element such as eV, Ti, or Apt, the toughness of rail steel can be improved even more stably. When Nb is heated at a low temperature during hot rolling, Nb (C, N) precipitates suppress austenite grain growth and contribute to grain refinement. Furthermore, toughness can be improved by refining the austenite grains after hot rolling by high temperature heating and low temperature finish rolling, and by refining the pearlite block size obtained after forced cooling. At this time, the effective lower limit of Nb addition amount is 0.0
0.05%, and if it exceeds 0.05%, coarse NbC will be produced, which will instead lead to embrittlement.
従ってＮｂの成分範囲を０．００５〜０．０５％に限定
した。ＶはＮｂとほぼ同様の傾向を示すが、加熱中に析
出するＶ （Ｃ，Ｎ）はＮｂ （Ｃ，Ｎ）より溶融温度
が低いため、レール圧延時の低温加熱時および再加熱温
度の低い領域でのみ、初期オーステナイト粒の細粒化に
寄与する。しかし■の０．０２％以下の添加では析出物
の数も少なく所定の効果は期待出来ず、０．２０％を超
えるとＶ（Ｃ，Ｎ）の粗大化によってかえって脆化を生
じさせる。このためＶの成分範囲を０．０２〜０．２０
％に限定したａＴｈは析出したＴｉ （Ｃ，Ｎ）が高温
でも溶融しないことから、通常のレール圧延加熱温度で
もオーステナイト粒の細粒化に効果を示す、しかし０．
０１％以下のＴｉではその効果は小さく、０．０５％超
ではＴｉＮ、ＴｉＣの粗大析出物が生じ靭性を低下させ
る。このためＴｉの成分範囲を０．０１〜０．０５％に
限定した。Therefore, the Nb component range was limited to 0.005 to 0.05%. V shows almost the same tendency as Nb, but V (C, N) that precipitates during heating has a lower melting temperature than Nb (C, N), so it is difficult to use during low-temperature heating during rail rolling and at low reheating temperatures. contributes to the refinement of the initial austenite grains. However, if 0.02% or less of (2) is added, the number of precipitates is too small and the desired effect cannot be expected, and if it exceeds 0.20%, embrittlement will occur due to coarsening of V(C,N). Therefore, the component range of V is set to 0.02 to 0.20.
Since precipitated Ti (C, N) does not melt even at high temperatures, aTh limited to 0.0% is effective in refining austenite grains even at normal rail rolling heating temperatures.
If the Ti content is less than 0.01%, the effect is small, and if it exceeds 0.05%, coarse precipitates of TiN and TiC are formed, reducing the toughness. For this reason, the Ti component range was limited to 0.01 to 0.05%.
Ａｌはその窒化物の析出を利用したオーステナイト粒の
細粒化元素として良く知られている。ＡｌもＶ同様オー
ステナイト粒成長抑制に寄与する析出物の溶解温度が低
いため、レール熱処理の再加熱温度の低い場合にその効
力を発揮するする。その下限値は０．００５％Ａｌであ
り、これ以下では粒成長抑制に効果を示さない、一方０
．０５％以上のＡｌを添加すると、鋼中に有害なＡｌ酸
化物（アルミナクラスター）が生成して著しく靭性を損
う。そこでＡｌの成分範囲を０．００５〜０゜０５％に
限定した。Al is well known as an element for refining austenite grains by utilizing its nitride precipitation. Like V, Al has a low melting temperature of precipitates that contribute to suppressing austenite grain growth, so it exhibits its effectiveness when the reheating temperature in rail heat treatment is low. Its lower limit is 0.005% Al, below which it has no effect on grain growth suppression;
．． If 0.5% or more of Al is added, harmful Al oxides (alumina clusters) are generated in the steel, significantly impairing toughness. Therefore, the Al component range was limited to 0.005 to 0.05%.
上記のような成分組成で構成されるレールは、転炉、電
気炉などの通常使用される溶解炉で溶製された溶鋼を、
造塊・分塊法あるいは連続鋳造法。Rails made of the above-mentioned composition are made by melting molten steel in commonly used melting furnaces such as converters and electric furnaces.
Ingot making/blowing method or continuous casting method.
さらに熱間圧延を経て製造される。熱間圧延を終えたレ
ールは、圧延終了後あるいは一旦低温度に冷却され熱処
理する目的で再加熱されたオーステナイト域温度から冷
却する。この際、レール鋼の靭性を高めるためには、圧
延終了後熱処理では圧延時加熱温度を出来るだけ低くし
、かつ低温仕上にしてオーステナイト粒を細粒化するこ
とが望ましい。また再加熱熱処理に際しても同様に再加
熱温度を出来るだけ低温度にすることが靭性を向上させ
るためには適わしい。この場合の冷却開始温度をオース
テナイト域温度にしたのは均一でかつ微細なパーライト
組織を生成させて耐摩耗性、耐損傷性に優れたレール鋼
を得るためである。また冷却は、列車の高荷重化に対抗
してレールを高強度化する目的で気体もしくは気液体に
よって行い、その冷却制御温度範囲は８００〜５００℃
である。Furthermore, it is manufactured through hot rolling. The hot-rolled rail is cooled from the austenite region temperature after rolling or once cooled to a low temperature and then reheated for the purpose of heat treatment. At this time, in order to improve the toughness of the rail steel, it is desirable to reduce the heating temperature during rolling as much as possible in the post-rolling heat treatment and to finish at a low temperature to refine the austenite grains. Further, in the reheating heat treatment, it is also suitable to keep the reheating temperature as low as possible in order to improve toughness. The reason why the cooling start temperature in this case is set to the austenite region temperature is to generate a uniform and fine pearlite structure to obtain a rail steel with excellent wear resistance and damage resistance. In addition, cooling is performed using gas or gas-liquid to strengthen the rails to cope with the increased load of trains, and the cooling control temperature range is 800 to 500 degrees Celsius.
It is.
尚、オーステナイト域温度から冷却制御開始温度までの
この間の冷却速度は任意な速度でよい、このような冷却
制御温度範囲は大断面レールから小断面レールまですべ
てのパーライト変態開始から終了までを含むものであっ
て、この間の冷却速度は２〜ｂ
Ｓｅｃ以下では高荷重化に対応して必要とされるＨ８３
４１以上の硬度が得られず、５℃／ｓｅｅを超える急速
冷却では、パーライト組織中に異組織（マルテイサイト
、ベーナイト）が混入し、靭性を著しく損う結果となる
。Note that the cooling rate during this period from the austenite region temperature to the cooling control start temperature may be any rate, and this cooling control temperature range includes all pearlite transformation from the start to the end from the large cross-section rail to the small cross-section rail. The cooling rate during this period is 2 to 2 b Sec or less, which is H83 which is required to cope with the high load.
If a hardness of 41 or more cannot be obtained and rapid cooling exceeds 5° C./see, foreign structures (marteisite, bainite) will be mixed into the pearlite structure, resulting in a significant loss of toughness.
［実施例及び発明の効果］
次に本発明により製造した高靭性を有する高強度レール
の製造実施例について述べる。[Examples and Effects of the Invention] Next, an example of manufacturing a high-strength rail having high toughness manufactured according to the present invention will be described.
第１表は供試鋼の化学成分および８００〜５００℃間の
強制冷却時の冷却速度を示す。Table 1 shows the chemical composition of the sample steel and the cooling rate during forced cooling between 800 and 500°C.
第２表は供試鋼レールの引張試験１頭表部硬度。Table 2 shows the hardness of the surface of the test steel rail in a tensile test.
および頭表面下３ｍ＋ｍより採取した２ｍ＋＋＋Ｕノツ
チシャルピー試験における＋２０℃での衝撃値を示す。And, the impact value at +20°C in a 2m+++U notch Charpy test taken from 3m+m below the head surface is shown.
この試験条件は熱処理レールにおける靭性を規定したソ
連のＧＯ８Ｔ規格にもとづくもので、同規格によれば高
強度熱処理レールの＋２０℃での衝撃値は２ 、２ ｋ
ｇｆｍ／ｃｍ”以上が必要とされている。These test conditions are based on the Soviet Union's GO8T standard, which stipulates the toughness of heat-treated rails. According to the standard, the impact value of high-strength heat-treated rails at +20°C is 2.2 k.
gfm/cm" or higher is required.
尚、レール鋼の＃撃値の規格は世界中でこのＧ。In addition, the standard for #shock value of rail steel is this G all over the world.
ＳＴによるものだけである。Only by ST.
発明鋼Ａは、Ｃｕによるパーライト変態抑制効果による
高強度化を図ったもので、Ｃｕを含有しない同−成分系
、同一冷却速度のものに比べてブリネル硬度で約２０ポ
イントの硬度増加が認められた６発明鋼ＡのＷＩ撃値は
３ 、１ ｋｇｆｍ／ｃｍ”が得られており、ＧＯ５Ｔ
規格を十分満足している。Invention steel A aims to achieve high strength due to the pearlite transformation suppressing effect of Cu, and has an increase in hardness of approximately 20 points on the Brinell hardness compared to steel of the same composition system and the same cooling rate that does not contain Cu. The WI impact value of 6-invention steel A was 3.1 kgfm/cm, and GO5T
Fully satisfies the standards.
発明鋼ＢはＣｕの変態点抑制効果と析出硬化によりブリ
ネル硬度約３５ポイントの硬度増加が認められた。Ｂ鋼
のｗＩ撃値はＡ鋼よりも高＜４．５ｋｇｆｍ／ｃｎ＋”
が得られた。Inventive steel B was found to have increased hardness by about 35 Brinell hardness points due to the transformation point suppressing effect of Cu and precipitation hardening. The wI impact value of B steel is higher than that of A steel <4.5kgfm/cn+”
was gotten.
発明鋼Ｃ−ＦはすＣｕ、Ｎｉを含む基本成分系にＮｂ、
Ｖ、Ｔｉ、Ａｌ等の細粒化元素を添加したもので１強度
的には基本成分系のＡｌｌと殆ど変化はないが、熱間圧
延時の加熱温度の低下や、再加熱時の最高加熱温度の低
下とこれら細粒化元素の組合せにより、基本成分系Ａ鋼
よりも衝撃値の改善効果が認められる。Invention steel C-F has a basic component system containing Cu and Ni, Nb,
Added grain refining elements such as V, Ti, Al, etc. In terms of strength, there is almost no difference from the basic component type Al, but there is a decrease in the heating temperature during hot rolling and the maximum heating during reheating. Due to the combination of the temperature reduction and these grain-refining elements, the impact value is improved more than the basic composition A steel.
比較鋼Ｇは、普通炭素鋼系の市販の普及型高強度熱処理
レールであるが、本発明鋼に比べて冷却速度を大幅に増
加させることによって高強度化が達成されているものの
、得られる衝撃値は低く、ＧＯ８Ｔ規格である２ 、
２ ｋｇｆｍ／ｃ＋＋”以上を満足出来ていない。Comparative steel G is a commercially available high-strength heat-treated rail made of ordinary carbon steel, and although it achieves high strength by significantly increasing the cooling rate compared to the steel of the present invention, the resulting impact The value is low and is GO8T standard 2,
2 kgfm/c++” or more cannot be satisfied.
比較鋼Ｈは、溶接性を付与するために低合金添加（ＳＬ
−Ｃｒ）された高強度熱処理レールの代表的な成分系を
示したものであるが、Ｃｒ含有量が高いために得られる
衝撃値は比較鋼Ｇよりもさらに低い。Comparative steel H has a low alloy addition (SL) to improve weldability.
-Cr), the impact value obtained is even lower than Comparative Steel G due to the high Cr content.
第１図は発明鋼ＡおよびＢと比較鋼ＧおよびＨの、レー
ルの代表的な溶接法であるフラッシュバット溶接継手部
の断面硬度分布を示したものである。尚、発明鋼Ｃ−Ｆ
はＡ鋼とはゾ同−傾向を示すため割愛した０発明鋼およ
び比較鋼Ｈは、母材部と継手部がほとんど一体となった
硬度分布を示しているのに対して、比較鋼Ｇでは、継手
部硬度が無視し得ぬほど低いために局部摩耗を生じさせ
、列車の衝撃的な負荷をもたらす、また、母材部と継手
部の硬度がほり等しい比較鋼Ｈにおいても、前記したよ
うにＣｒ含有量が高いために衝撃特性の優れたものが得
られない、尚レールの耐摩耗性は硬度と強い相関を示す
ことは広く知られており、本発明鋼はパーライト組織で
得られる到達硬度の最高水準を示していることから十分
な耐摩耗性を発揮する。FIG. 1 shows the cross-sectional hardness distribution of flash butt welded joints of invention steels A and B and comparative steels G and H, which is a typical welding method for rails. In addition, invention steel C-F
Invention steel 0 and comparative steel H, which are omitted because they show the same tendency as steel A, show a hardness distribution in which the base metal and the joint part are almost integrated, whereas in comparison steel G, , the hardness of the joint part is so low that it cannot be ignored, causing local wear and causing an impact load on the train. Also, as mentioned above, even in comparative steel H, where the hardness of the base metal part and the joint part are almost equal, However, it is widely known that the wear resistance of rails has a strong correlation with hardness, and the steel of the present invention has a high Cr content that makes it difficult to obtain excellent impact properties. It exhibits sufficient wear resistance as it exhibits the highest level of hardness.
また、耐損傷性に関しても微細パーライト組織が損傷性
に対して有効であることが良く知られており、本発明鋼
はその引張特性が示すごとく、安定した微細パーライト
組織を示していることから十分な耐損傷性を備えている
と言える。In addition, it is well known that a fine pearlite structure is effective against damage resistance, and the steel of the present invention has a stable fine pearlite structure as shown by its tensile properties. It can be said that it has excellent damage resistance.
このように本発明鋼は、レール基本特性である耐摩耗性
、耐損傷性に加え、より一層の高荷重条件下での使用に
際しても、従来よりも高い靭性を有する高強度熱処理レ
ールである。As described above, the steel of the present invention is a high-strength heat-treated rail that not only has wear resistance and damage resistance, which are the basic characteristics of the rail, but also has higher toughness than conventional rails even when used under even higher load conditions.
第１図は発明鋼と比較鋼のフラッシュバット溶接継手部
の断面硬度分布を示す図である。FIG. 1 is a diagram showing the cross-sectional hardness distribution of flash butt welded joints of the invention steel and comparative steel.
Claims (2)
を熱間圧延終了後あるいは熱処理する目的で加熱された
オーステナイト域温度からの冷却において、８００〜５
００℃間を冷却速度２〜５℃／ｓｅｃで急速冷却するこ
とを特徴とする靭性にすぐれた高強度レールの製造法。(1) C: 0.55-0.85% Si: 0.20-1.20% Mn: 0.5-1.65% Cr: 0.1-0.19% Cu: 0. 2-1.0% Ni: 0.2-1.0% with the balance being iron and inevitable impurities Cooling the head of the rail from the austenite region temperature heated after hot rolling or for the purpose of heat treatment. In, 800-5
A method for manufacturing a high-strength rail with excellent toughness, characterized by rapid cooling between 00°C and a cooling rate of 2 to 5°C/sec.
不純物からなるレールの頭部を、熱間圧延終了後あるい
は熱処理する目的で加熱されたオーステナイト域温度か
らの冷却において、８００〜５００℃間を冷却速度２〜
５℃／ｓｅｃで急速冷却することを特徴とする靭性にす
ぐれた高強度レールの製造法。(2) In weight%, C: 0.55-0.85% Si: 0.20-1.20% Mn: 0.5-1.65% Cr: 0.1-0.19% Cu: 0. In addition to 2-1.0% Ni: 0.2-1.0%, Nb: 0.005-0.05% V: 0.02-0.20% Ti: 0.01-0.05% Al : 0.005 to 0.05% of one or more of the following, with the remainder consisting of iron and unavoidable impurities: The austenite region temperature of the rail head heated after hot rolling or for the purpose of heat treatment. When cooling from 800 to 500℃, the cooling rate is 2 to
A method for manufacturing high-strength rails with excellent toughness, characterized by rapid cooling at 5°C/sec.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21146286A JPS6369918A (en) | 1986-09-10 | 1986-09-10 | Manufacture of high strength rail having superior toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21146286A JPS6369918A (en) | 1986-09-10 | 1986-09-10 | Manufacture of high strength rail having superior toughness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6369918A true JPS6369918A (en) | 1988-03-30 |
Family
ID=16606339
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21146286A Pending JPS6369918A (en) | 1986-09-10 | 1986-09-10 | Manufacture of high strength rail having superior toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6369918A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011162822A (en) * | 2010-02-08 | 2011-08-25 | Nippon Steel Corp | Pearlite rail having superior wear resistance and method for manufacturing the same |
| EP2006406A4 (en) * | 2006-03-16 | 2015-08-12 | Jfe Steel Corp | High-strength pearlite rail with excellent delayed-fracture resistance |
| CN113699452A (en) * | 2021-08-30 | 2021-11-26 | 宝武集团马钢轨交材料科技有限公司 | Steel for tramcar elastic wheel rim and heat treatment method and production method thereof |
-
1986
- 1986-09-10 JP JP21146286A patent/JPS6369918A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2006406A4 (en) * | 2006-03-16 | 2015-08-12 | Jfe Steel Corp | High-strength pearlite rail with excellent delayed-fracture resistance |
| JP2011162822A (en) * | 2010-02-08 | 2011-08-25 | Nippon Steel Corp | Pearlite rail having superior wear resistance and method for manufacturing the same |
| CN113699452A (en) * | 2021-08-30 | 2021-11-26 | 宝武集团马钢轨交材料科技有限公司 | Steel for tramcar elastic wheel rim and heat treatment method and production method thereof |
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