JP3940838B2 - Rolling and sliding contact parts and manufacturing method thereof - Google Patents

Description

【００１８】
極値統計法は、「金属疲労 微少欠陥と介在物の影響」（村上敬宜著、養賢堂発行、第２３３〜２４０頁）に記載されているように、以下に述べるような方法である。すなわち、ある基本分布関数に従うデータの集合から一定の数のデータの集合取り出した時、各集合の極値（最大値、最小値）が従う分布を極値分布という。基本分布関数が正規分布や指数分布であってもその極値分布は異なった分布となるが、この極値分布について解析するのが極値統計法である。基本分布関数のすそ野が指数的に減少すると見なせる基本分布関数（たとえば正規分布、指数分布）を極値分布では２重指数分布と呼び、２重指数分布は極値分布上では直線となるため任意の予測領域内での最大値を推定できる。軸受鋼中の介在物分布も指数分布となるため、極値統計法を用いて任意の予測面積（体積）中の予測最大径（ area _ｍａｘ ） ^１／２ を算出することが可能となる。ここで、極値統計法を用いて予測最大径を求める時に必要となるパラメータを表２に示す。表２により表３の最大介在物分布直線を求めて予測最大径を算出する。このときの極値統計グラフの例を図１に示す。
【００１９】
【表２】

【００２０】
【表３】

【００２１】
さらに、請求項１の発明において、上記式 (i) は、軸受鋼に含まれる不純物の含有量や非金属介在物の大きさから複数の寿命支配パラメータ候補を選択し、全ての寿命支配パラメータ候補を説明変数とし、目的変数を寿命試験における実際の寿命として重回帰分析を行って予備寿命推定式を導出し、前記寿命支配パラメータ候補の中から自由度２重調整済み寄与率が最大になる説明変数を求めるとともに、この説明変数を用いて再度重回帰分析を行って求められたものである。
ここで、スラスト型寿命試験器を用いて行った実際の転動疲労寿命Ｌ _１０ と、上記式 (i) で求められたＬ _１０ｅ （推定Ｌ _１０ 寿命）との関係を図２に示す。
【００２２】
請求項１の発明によれば、表面硬さが増大して潤滑油中に混入したＨＲＣ６４以上の表面硬さを有する異物により圧痕が生成しなくなるとともに、耐摩耗性が向上し、その結果転がり接触部品またはすべり接触部品を用いた製品の長寿命化を図ることができる。しかも、軸受用として大量生産される軸受鋼よりなるので、材料コストが安くなり、その結果トータルの製造コストが安くなる。軸受鋼の中でもJIS ＳＵＪ２は特に大量生産されるため、これを用いると材料コストが極めて安くなるので、好ましい。
【００２３】
また、請求項１の発明において、前記浸炭処理温度が８４０〜８７０℃であることが好ましい。この場合、従来の肌焼き鋼に施す浸炭処理や浸炭窒化処理の加熱温度よりも低くなり、熱処理コストが安くなる。したがって、トータルの製造コストが安くなる。
【００２４】
請求項１の発明の場合、前記鋼は低清浄度品で安価に手に入れることができるので、転がり接触部品またはすべり接触部品の製造コストが安くなる。
【００２５】
請求項２の発明による転がり、すべり接触部品は、請求項１の発明において、前記球状炭化物の量が面積率で５〜１５％となされているものである。球状炭化物の量の上限を面積率で１５％にするのは、次の理由による。すなわち、球状炭化物の量を面積率で１５％を越えたものにするには浸炭処理時間を長くしなければならず、その結果熱処理コストが高くなって、面積率が１５％以下の場合に比べてトータルの製造コストが高くなるからである。
【００２６】
請求項３の発明による転がり、すべり接触部品は、請求項１の発明において、前記球状炭化物の量が面積率で１０〜２０％でかつその粒径が２μｍ以下となされているものである。球状炭化物の量の下限を面積率で１０％としたのは、１０％未満になると、ミクロンオーダおよびサブミクロンオーダの炭化物の量が不足して寿命を向上させる効果が不十分になるおそれがあるからである。ここで、ミクロンオーダの炭化物は、疲労の原因となるすべり帯の形成を防止する効果があり、サブミクロンオーダの炭化物は、すべり帯の形成を防止する効果はないが、すべり帯を分散させる効果がある。また、球状炭化物の粒径を２μｍ以下としたのは、２μｍを越えると、非金属介在物と同様に疲労亀裂の起点となるとともに、靭性が不十分になるおそれがあるからである。
【００２７】
請求項４の発明による転がり、すべり接触部品は、請求項１〜３のうちのいずれかの発明において、前記表層部の残留オーステナイト量が５〜２０vol％、同じく圧縮残留応力が１００MPa以上となされているものである。転がり接触部品またはすべり接触部品の表面硬さをＨＲＣ６７以上とするには、表層部の残留オーステナイト量を２０vol％以下、好ましくは２０vol％未満とする。また、靭性を考慮して残留オーステナイト量の下限は５vol％とする。さらに、表層部の圧縮残留応力が１００MPa以上であると、亀裂の進展を抑制することができ、その結果転がり接触部品またはすべり接触部品を用いた製品の一層の長寿命化を図ることができる。
【００２８】
請求項５の発明による転がり、すべり接触部品の製造方法は、Ｃ０．８０〜１．２０質量％、Ｓｉ０．１５〜０．７０質量％、Ｍｎ０．２５〜１．１５質量％、Ｃｒ０．９０〜１．６０質量％、Ｍｏ０．２５質量％以下を含み、残部Ｆｅおよび不可避不純物よりなる鋼であって、かつこの鋼を用いた転がり軸受の下記式 (i) で表されるスラスト寿命試験機における推定Ｌ _１０ 寿命が１０ ^７ 以下である軸受鋼より所定の形状に形成された加工済み転がり、接触部品素材を、カーボンポテンシャルが１．２％以上である浸炭雰囲気中において８４０〜８７０℃で３時間以上加熱することにより浸炭処理を施した後急冷し、ついでサブゼロ処理を施すことにより、表面から０．５ｍｍの深さまでの範囲の表層部の全炭素量を１．０〜１．６質量％とするとともに、前記表層部のマトリックス中の固溶炭素量を０．６〜１．０質量％とし、前記表層部に球状炭化物を析出させて球状炭化物の量を面積率で５〜２０％でかつその粒径を３μｍ以下とし、さらに前記表層部の表面硬さをロックウェルＣ硬さで６７〜６９とすることを特徴とするものである。
【００２９】
Ｌ _１０ｅ ＝２６．１８０１１・ＥＸＰ｛−０．５３２・Ｆ _１ * （ｘ _１ 、ｘ _２ ）
−０．１４３・Ｆ _２ * （ｘ _３ 、ｘ _４ ）−０．５０３・Ｆ _３ * （ｘ _５ ）｝ … (i)
ここで、
Ｆ _１ * （ｘ _１ 、ｘ _２ ）：（ｘ _１ ・ｘ _２ −０．０１１４３５）／０．００４７３１
Ｆ _２ * （ｘ _３ 、ｘ _４ ）：（ｘ _３ ・ｘ _４ −０．０２７８９５）／０．０１３２７８
Ｆ _３ * （ｘ _５ ）：（ｘ _５ −０．００２６４６）／０．００１５０３
ｘ _１ ：Ｏ含有量、質量％
ｘ _２ ：酸化物系介在物の予測最大径、μｍ
ｘ _３ ：Ｔｉ含有量、質量％
ｘ _４ ：チタン系介在物の予測最大径、μｍ
ｘ _５ ：Ｓ含有量、質量％
請求項５の発明において、浸炭処理における各数値の限定理由は次の通りである。なお、表層部の全炭素量、表層部のマトリックス中の固溶炭素量、表層部の球状炭化物の量、表層部の球状炭化物の粒径および表層部の表面硬さについては、限定理由は請求項１の発明の場合と同じである。
【００３０】
浸炭処理雰囲気のカーボンポテンシャル
このカーボンポテンシャルを１．２％以上に限定したのは、１．２％未満では、炭素含有量が１質量％程度である軸受鋼に対してほとんど浸炭されないことになり、表層部の硬さおよび炭化物の面積率を所望のものにすることができず、しかも炭化物の微細化を図ることができないからである。
【００３１】
浸炭処理温度
この温度を８４０〜８７０℃に限定したのは、下限値未満であるとカーボンポテンシャルのところで述べたような必要な浸炭を行うことができず、上限値を越えると表層部の結晶粒度が大きくなりすぎるとともに巨大炭化物が析出して強度が低下するからである。すなわち、降伏強さは結晶粒度の−１／２乗に比例するので、結晶粒度が大きくなりすぎると強度が低下する。
【００３２】
浸炭処理時間
この時間を３時間以上に限定したのは、３時間未満であると浸炭深さが不足するからである。
【００３３】
請求項５の発明において、サブゼロ処理は−５０〜−１００℃に１時間以上冷却することにより行うのがよい。
【００３４】
請求項５の発明によれば、軸受用として多く用いられる軸受鋼よりなる素材を用いるので、材料コストが安くなる。しかも、浸炭処理温度が８４０〜８７０℃であるとともに、１度の浸炭処理の後急冷し、ついでサブゼロ処理を行うだけであるから、熱処理コストが安くなる。したがって、軸受部品のトータルの製造コストが安くなる。また、浸炭処理の後急冷し、ついでサブゼロ処理を施しているので、表層部の表面硬さをＨＲＣ６７〜６９にすることができる。したがって、転がり接触部品またはすべり接触部品の長寿命化を図ることが可能になる。軸受鋼の中でもJIS ＳＵＪ２は特に大量生産されるため、これを用いると材料コストが極めて安くなるので、好ましい。
【００３５】
請求項５の発明において、カーボンポテンシャルを１．２〜１．４％とすることが好ましい。カーボンポテンシャルが１．４％を越えると、大量の煤が発生するという問題があるからである。
【００３６】
さらに、請求項５の発明において、加熱時間を３．５〜５時間とすることが好ましい。加熱時間が５時間を超えると、熱処理コストが高くなるとともに、炭化物が巨大化するという問題があるからである。
【００３７】
請求項６の発明による転がり、すべり接触部品の製造方法は、Ｃ０．８０〜１．２０質量％、Ｓｉ０．１５〜０．７０質量％、Ｍｎ０．２５〜１．１５質量％、Ｃｒ０．９０〜１．６０質量％、Ｍｏ０．２５質量％以下を含み、残部Ｆｅおよび不可避不純物よりなる鋼であって、かつこの鋼を用いた転がり軸受の下記式 (i) で表されるスラスト寿命試験機における推定Ｌ _１０ 寿命が１０ ^７ 以下である軸受鋼より所定の形状に形成された加工済み転がり、接触部品素材を、カーボンポテンシャルが０．９〜１．１％の雰囲気中において９３０〜９７０℃で１時間以上加熱することにより既存の炭化物をマトリックス中に溶け込ませる処理を施した後急冷し、ついでカーボンポテンシャルが１．２％以上の雰囲気中において８４０〜８７０℃で３時間以上加熱することにより浸炭処理を施した後急冷し、ついでサブゼロ処理を施すことにより、表面から０．５ｍｍの深さまでの範囲の表層部の全炭素量を１．０〜１．６質量％とするとともに、前記表層部のマトリックス中の固溶炭素量を０．６〜１．０質量％とし、前記表層部に球状炭化物を析出させて球状炭化物の量を面積率で５〜２０％でかつその粒径を３μｍ以下とし、さらに前記表層部の表面硬さをロックウェルＣ硬さで６７〜６９とすることを特徴とするものである。
【００３８】
Ｌ _１０ｅ ＝２６．１８０１１・ＥＸＰ｛−０．５３２・Ｆ _１ * （ｘ _１ 、ｘ _２ ）
−０．１４３・Ｆ _２ * （ｘ _３ 、ｘ _４ ）−０．５０３・Ｆ _３ * （ｘ _５ ）｝ … (i)
ここで、
Ｆ _１ * （ｘ _１ 、ｘ _２ ）：（ｘ _１ ・ｘ _２ −０．０１１４３５）／０．００４７３１
Ｆ _２ * （ｘ _３ 、ｘ _４ ）：（ｘ _３ ・ｘ _４ −０．０２７８９５）／０．０１３２７８
Ｆ _３ * （ｘ _５ ）：（ｘ _５ −０．００２６４６）／０．００１５０３
ｘ _１ ：Ｏ含有量、質量％
ｘ _２ ：酸化物系介在物の予測最大径、μｍ
ｘ _３ ：Ｔｉ含有量、質量％
ｘ _４ ：チタン系介在物の予測最大径、μｍ
ｘ _５ ：Ｓ含有量、質量％
請求項６の発明において、熱処理における各数値の限定理由は次の通りである。なお、表層部の全炭素量、表層部のマトリックス中の固溶炭素量、表層部の球状炭化物の量、表層部の球状炭化物の粒径および表層部の表面硬さについては、限定理由は請求項１の発明の場合と同じである。
【００３９】
既存の炭化物をマトリックス中に溶け込ませる工程
この工程における雰囲気中のカーボンポテンシャルを０．９〜１．１％に限定したのは、転がり接触部品またはすべり接触部品に対して浸炭および脱炭を起こさせないためである。１．１％を越えると炭素含有量が１質量％程度である軸受鋼に対して浸炭が起こり、０．９％未満であると脱炭が起こる。
【００４０】
この工程における加熱温度を９３０〜９７０℃に限定したのは、９３０℃未満であると球状焼鈍後存在している第２相としての炭化物のマトリックス中への固溶が不十分であり、９７０℃を越えると焼割れを起こす可能性があるからである。
【００４１】
さらに、この工程における加熱時間を１時間以上に限定したのは、１時間未満であると球状焼鈍後存在している第２相としての炭化物のマトリックス中への固溶が不十分になるからである。
【００４２】
浸炭工程
この工程における雰囲気中のカーボンポテンシャルを１．２％以上に限定したのは、１．２％未満では、炭素含有量が１質量％程度である軸受鋼に対してほとんど浸炭されないことになり、表層部の硬さおよび炭化物の面積率を所望のものにすることができず、しかも炭化物の微細化を図ることができないからである。なお、カーボンポテンシャルの上限は、大量の煤の発生を防止するために１．４％以下とすることが好ましい。
【００４３】
この工程における加熱温度を８４０〜８７０℃に限定したのは、下限値未満であるとカーボンポテンシャルのところで述べたような必要な浸炭を行うことができず、上限値を越えると表層部の結晶粒度が大きくなりすぎるとともに巨大炭化物が析出して強度が低下するからである。すなわち、降伏強さは結晶粒度の−１／２乗に比例するので、結晶粒度が大きくなりすぎると強度が低下する。
【００４４】
さらに、この工程における加熱時間を３時間以上に限定したのは、３時間未満であると必要な浸炭深さが得られないからである。
【００４５】
請求項６の発明において、サブゼロ処理は−５０〜−１００℃に１時間以上冷却することにより行うのがよい。
【００４６】
請求項６の発明によれば、軸受用として多く用いられる軸受鋼よりなる素材を用いるので、材料コストが安くなる。したがって、軸受部品のトータルの製造コストが安くなる。しかも、既存の炭化物をマトリックス中に溶け込ませる処理を施した後浸炭処理を施し、さらにサブゼロ処理を施しているので、表層部の表面硬さをＨＲＣ６７〜６９にすることができる。したがって、転がり接触部品またはすべり接触部品の長寿命化を図ることが可能になる。軸受鋼の中でもJIS ＳＵＪ２は特に大量生産されるため、これを用いると材料コストが極めて安くなるので、好ましい。
【００４７】
請求項１、請求項５および請求項６の発明において、内部起点剥離の要因となる最大剪断応力が作用する表面からの深さは、接触条件によって異なるが、多くの転がり、すべり接触部品おいて０．５ｍｍ程度までである。そして、この範囲内において、全炭素量、マトリックス中の固溶炭素量、球状炭化物の量、表面硬さを上述したようにすることにより強度を向上させ、その結果所定の目的が達成されるからである。
【００４８】
請求項５および６において用いられる軸受鋼は、低清浄度品で安価に手に入れることができるので、転がり接触部品またはすべり接触部品の製造コストが安くなる。しかも、請求項５または６の発明の方法によれば、このような低清浄度品を用いたとしても、所望の性能を持った転がり接触部品またはすべり接触部品を製造することができる。
【００４９】
【発明の実施形態】
以下、この発明の実施例を比較例とともに説明する。
【００５０】
実施例１〜２および比較例１〜３
Ｃ１．０１質量％、Ｓｉ０．２４質量％、Ｍｎ０．３６質量％、Ｃｒ１．４６、Ｍｏ０．０１質量％を含み、残部Ｆｅおよび不可避不純物からなる鋼（JIS ＳＵＪ２）であって、前記式(i)で求められる推定Ｌ_１０寿命（Ｌ_１０ｅ）が１０^７以下である鋼を用いて型番６２０６の転がり軸受に使用される５種類の内輪素材を形成した。
【００５１】
ついで、これらの内輪素材に、以下に示す熱処理条件で熱処理を施して内輪（実施例１〜２および比較例１〜３）を製造した。
【００５２】
熱処理条件１は、カーボンポテンシャル１．３％の雰囲気中において８５０℃で３．５時間加熱した後８０℃に油冷し、ついで−７５℃で１時間冷却してサブゼロ処理を施すものである（実施例１）。
【００５３】
熱処理条件２は、カーボンポテンシャル１．１％の雰囲気中において９５０℃で２時間加熱した後８０℃に油冷し、ついでカーボンポテンシャル１．３％の雰囲気中において８５０℃で３．５時間加熱した後８０℃に油冷し、ついで−７５℃で１時間冷却してサブゼロ処理を施すものである（実施例２）。
【００５４】
熱処理条件３は、カーボンポテンシャル０．６％の雰囲気中において、８５０℃で０．７時間加熱した後、８０℃に油冷するものである（比較例１）。
【００５５】
熱処理条件４は、カーボンポテンシャル１．３％の雰囲気中において３．５時間加熱した後８０度に油冷するものである（比較例２）。
【００５６】
熱処理条件５は、カーボンポテンシャル１．１％の雰囲気中において９５０℃で２時間加熱した後８０℃に油冷し、ついでカーボンポテンシャル１．３％の雰囲気中において８５０℃で３．５時間加熱した後８０℃に油冷するものである（比較例３）。
【００５７】
なお、上述した熱処理条件１〜５においては、いずれの場合も最後に１６０℃で２時間加熱する焼戻し処理が施される。
【００５８】
これら５種類の内輪の軌道面の表面硬さ(HRC)、軌道最表面の全炭素量、軌道最表面のマトリックス中の固溶炭素量、軌道最表面に析出した球状炭化物の量（面積率）、軌道最表面に析出した球状炭化物の最大粒径、表面から深さ５０μｍの位置での残留オーステナイト量（γ_Ｒ量）、表面から深さ５０μｍの位置での圧縮残留応力は、表４に示す通りである。
【００５９】
【表４】

【００６０】
評価試験
実施例１〜２および比較例１〜３の内輪を、JIS ＳＵＪ２からなりかつ通常の浸炭窒化処理が施されてなる外輪および玉と組み合わせて型番６２０６Ｃ３の玉軸受を組立てた。そして、これらの玉軸受を使用し、異物が混入した潤滑油、および清浄な潤滑油を用いてそれぞれ寿命試験を行った。異物が混入した潤滑油を用いた場合の試験条件は表５に示す通りであり、清浄な潤滑油を用いた場合の試験条件はこれから異物を除いたものである。
【００６１】
【表５】

【００６２】
なお、表５に示す試験機は、同時に２個の玉軸受の試験を行うことが可能であり、表４中のラジアル荷重は、１つの玉軸受のラジアル荷重を意味する。
【００６３】
寿命試験の結果も表４に示す。
【００６４】
表４中のＬ_１０寿命は、比較例１の場合を１とし、これを基準として表したものである。
【図面の簡単な説明】
【図１】 表２により求めた表４の最大介在物分布直線を示すグラフである。
【図２】 推定Ｌ_１０寿命と実Ｌ_１０寿命との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling / sliding contact component and a method for manufacturing the same, and more particularly, a rolling contact component such as a rolling bearing component, a roller cam follower, or a sliding bearing component, a roller support shaft for a rocker arm for an automobile engine, a cam lifter for an automotive engine, The present invention relates to a sliding contact part such as a part on which a cam surface is formed of both inner and outer wheels of a directional clutch.
[0002]
In this specification, the term “rolling contact” includes not only pure rolling contact but also rolling contact with sliding contact.
[0003]
[Prior art and problems to be solved by the invention]
For example, as a bearing ring and rolling element of a rolling bearing used using lubricating oil mixed with foreign matter, conventionally, in order to extend the life of the rolling bearing, the surface hardness is increased, for example, Rockwell C hardness. (Hereinafter referred to as HRC) 62-66 are used.
[0004]
However, conventional rolling bearing races and rolling elements are assumed to be metal powder or foundry sand having a surface hardness of about HRC58 to 62 as foreign matter mixed in the lubricating oil, and HRC64 such as abrasive grains. It has been found that when a lubricating oil mixed with foreign matters having the above surface hardness is used, the life of the rolling bearing cannot be extended. In the case of lubricating oil mixed with foreign matters of HRC64 or higher such as abrasive grains, it has been found that it is effective to further increase the surface hardness of the rolling bearing part. To increase the surface hardness It has also been found that increasing the amount of carbon in the steel that is the material of the races and rolling elements is a simple method. However, increasing the amount of carbon in the steel is inappropriate because it causes a decrease in grain boundary strength due to precipitation of fine carbides on the grain boundaries.
[0005]
Further, as the conventional rolling bearing parts as described above, those produced by carburizing or carbonitriding a bearing part material formed in a predetermined shape by case hardening steel have been used.
[0006]
However, the amount of case-hardened steel applied to the bearing is small, and since it is not mass-produced for bearings, the material cost is high, and the heat treatment cost for carburizing and carbonitriding of case-hardened steel is also high. Therefore, there is a problem that the total manufacturing cost of the rolling bearing parts is increased.
[0007]
Therefore, it is conceivable to manufacture rolling bearing parts by subjecting bearing parts made of bearing steel such as JIS SUJ2 to a predetermined shape by carburizing or carbonitriding. Both increase and carbide refinement cannot be achieved at the same time. For example, if carburizing treatment is applied to JIS SUJ2, which originally has high carbon and carbide, the surface hardness is increased, and the existing carbide grows further. Since it grows into a carbide, there is a problem that the service life is reduced when a lubricating oil mixed with foreign matters is used.
[0008]
An object of the present invention is to provide a rolling and sliding contact component and a method for manufacturing the same that can solve the above-described problems and can extend the life of a lubricating oil mixed with foreign matter having a surface hardness of HRC64 or higher. It is to provide.
[0009]
[Means for Solving the Problems and Effects of the Invention]
The rolling and sliding contact parts according to the invention of claim 1 are: C0.80 to 1.20 mass%, Si0.15 to 0.70 mass%, Mn0.25 to 1.15 mass%, Cr0.90 to 1.60. Estimated L ₁₀ in a thrust life tester represented by the following formula (i) of a rolling bearing using this steel, which is a steel comprising the remaining Fe and unavoidable impurities, including a mass% and Mo 0.25 mass% or less. It is made of bearing steel with a life of 10 ⁷ or less , carburized, and the total carbon content of the surface layer in the range from the surface to a depth of 0.5 mm is 1.0 to 1.6 mass%. The amount of solid solution carbon in the matrix of the surface layer portion is 0.6 to 1.0% by mass, spherical carbide is precipitated in the surface layer portion, and the amount of the spherical carbide is 5 to 20 in area ratio. % And the particle size is 3 μm or less. Furthermore the surface hardness of the surface layer portion is characterized in that it is made with 67 to 69 in Rockwell C hardness.
[0010]
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass%
In the first aspect of the present invention, the reasons for limiting each numerical value are as follows.
[0011]
The total amount of carbon in the surface layer is limited to 1.0 to 1.6% by mass because the carbide becomes extremely coarse and cannot be refined if the upper limit is exceeded. The lower limit value is inevitably determined from the base of bearing steel such as JIS SUJ2.
[0012]
The amount of solid solution carbon in the matrix of the surface layer part was limited to 0.6 to 1.0% by mass because the desired surface hardness could not be obtained if it was less than the lower limit value. This is because indentations are generated by foreign matters mixed in the lubricating oil, and when the upper limit is exceeded, the amount of fine spherical carbide in the surface layer becomes less than 5% in terms of area ratio and wear resistance decreases.
[0013]
The amount of fine spherical carbide in the surface layer part The amount of fine spherical carbide is limited to 5 to 20% in terms of area ratio. When the amount is less than the lower limit, the wear resistance is lowered, and when the upper limit is exceeded, coarse carbides are formed. This is because this coarse carbide becomes a starting point of fatigue cracks and leads to a shortened life of the rolling contact part or the sliding contact part.
[0014]
The particle size of the fine spherical carbide in the surface layer portion This particle size is limited to 3 μm or less because if it exceeds 3 μm, it becomes the starting point of fatigue cracks as in the case of non-metallic inclusions, and toughness cannot be ensured. is there.
[0015]
Surface hardness of the surface layer portion When the surface hardness is 67 to 69 in HRC, even if the hardness of the foreign matter mixed in the lubricating oil is 64 HRC or more, the formation of indentation by the foreign matter is prevented. The surface hardness is preferably more than 67. However, if the surface hardness exceeds HRC69, the toughness of the material itself is impaired. In particular, in the case of a rolling bearing part, if the surface hardness of the raceway surface or the rolling surface exceeds HRC69, the rolling fatigue strength is reduced and the generation of indentation is prevented, but the rolling fatigue life is reduced. Therefore, the upper limit of the surface hardness is HRC69.
[0016]
In the invention of claim 1, the titanium-based inclusion is TiN. The predicted maximum diameter (predicted area 10000 mm ² ) of oxide inclusions and titanium inclusions was measured using the image analysis apparatus under the conditions shown in Table 1, and the extreme value statistical method. Ask for. Further, the inclusion projection surface for calculating the predicted maximum diameter is a cross section perpendicular to the contact surface between the life test piece and the ball. Here, since oxide inclusions and titanium inclusions are almost spherical, the projected surface shapes are almost the same regardless of the cross section of the life test piece, so the predicted maximum diameter is the inclusion projected area. To obtain the diameter by yen conversion .
[0017]
[Table 1]

[0018]
The extreme value statistical method is a method as described below as described in “Effects of Metallic Fatigue Minor Defects and Inclusions” (Keiyoshi Murakami, Yokendo, pp. 233-240). . That is, when a certain number of sets of data are extracted from a set of data according to a certain basic distribution function, the distribution that the extreme values (maximum value, minimum value) of each set follow is called an extreme value distribution. Even if the basic distribution function is a normal distribution or an exponential distribution, the extreme value distribution is different. The extreme value statistical method analyzes the extreme value distribution. A basic distribution function (for example, normal distribution, exponential distribution) that can be considered that the base of the basic distribution function decreases exponentially is called a double exponential distribution in the extreme value distribution, and the double exponential distribution is a straight line on the extreme value distribution. The maximum value in the prediction region can be estimated. Since the inclusion distribution in the bearing steel is also an exponential distribution, it is possible to calculate the predicted maximum diameter ( area _max ) ^1/2 in an arbitrary predicted area (volume) using the extreme value statistical method . Here, Table 2 shows parameters necessary for obtaining the predicted maximum diameter using the extreme value statistical method. The maximum inclusion distribution line in Table 3 is obtained from Table 2 and the predicted maximum diameter is calculated. An example of the extreme value statistical graph at this time is shown in FIG .
[0019]
[Table 2]

[0020]
[Table 3]

[0021]
Furthermore, in the invention of claim 1, the above formula (i) is obtained by selecting a plurality of life dominating parameter candidates from the content of impurities contained in the bearing steel and the size of the nonmetallic inclusions. Is used as the explanatory variable, and the objective variable is the actual life in the life test, a multiple regression analysis is performed to derive a preliminary life estimation formula, and the degree of freedom adjusted for the degree of freedom double adjustment is maximized from the life control parameter candidates In addition to obtaining a variable, this is obtained by performing a multiple regression analysis again using this explanatory variable.
Here, it is shown the actual rolling fatigue life L ₁₀ performed with a thrust type life tester, the relationship between L _10e obtained by the above formula (i) _(estimated L ₁₀ life) in FIG.
[0022]
According to the first aspect of the present invention, the surface hardness increases and foreign matter having a surface hardness of HRC64 or higher mixed in the lubricating oil does not generate indentation, and wear resistance is improved, resulting in rolling contact. It is possible to prolong the life of products using parts or sliding contact parts. Moreover, since it is made of bearing steel that is mass-produced for bearings, the material cost is reduced, and as a result, the total manufacturing cost is reduced. Among bearing steels, JIS SUJ2 is particularly mass-produced, and therefore, using it is preferable because the material cost is extremely low.
[0023]
In the invention of claim 1, the carburizing temperature is preferably 840 to 870 ° C. In this case, it becomes lower than the heating temperature of the carburizing treatment or carbonitriding treatment applied to the conventional case-hardened steel, and the heat treatment cost is reduced. Therefore, the total manufacturing cost is reduced .
[0024]
In the case of the invention of claim 1 , since the steel can be obtained at low cost with a low cleanliness product, the manufacturing cost of rolling contact parts or sliding contact parts is reduced.
[0025]
The rolling / sliding contact part according to the invention of claim 2 is the invention according to claim 1 , wherein the amount of the spherical carbide is 5 to 15% in terms of area ratio. The reason why the upper limit of the amount of spherical carbide is 15% in terms of area ratio is as follows. That is, in order to make the amount of spherical carbides more than 15% in area ratio, the carburizing time must be lengthened. As a result, the heat treatment cost becomes higher, compared with the case where the area ratio is less than 15%. This is because the total manufacturing cost increases.
[0026]
The rolling / sliding contact component according to the invention of claim 3 is the rolling / sliding contact component according to claim 1 , wherein the amount of the spherical carbide is 10 to 20% in terms of area ratio and the particle size thereof is 2 μm or less. The reason why the lower limit of the amount of spherical carbide is set to 10% in terms of area ratio is that if it is less than 10%, the amount of carbide of micron order and submicron order is insufficient and the effect of improving the life may be insufficient. Because. Here, micron-order carbide has the effect of preventing the formation of slip bands that cause fatigue, and sub-micron order carbide has no effect to prevent the formation of slip bands, but the effect of dispersing the slip bands. There is. The reason why the particle size of the spherical carbide is set to 2 μm or less is that when it exceeds 2 μm, it becomes a starting point of fatigue crack as in the case of non-metallic inclusions, and the toughness may be insufficient.
[0027]
The rolling and sliding contact component according to the invention of claim 4 is the invention according to any one of claims 1 to 3 , wherein the amount of retained austenite of the surface layer portion is 5 to 20 vol%, and the compressive residual stress is 100 MPa or more. It is what. In order to make the surface hardness of the rolling contact component or the sliding contact component HRC67 or more, the amount of retained austenite in the surface layer portion is set to 20 vol% or less, preferably less than 20 vol%. Further, considering the toughness, the lower limit of the amount of retained austenite is 5 vol%. Furthermore, when the compressive residual stress of the surface layer portion is 100 MPa or more, the progress of cracks can be suppressed, and as a result, the life of products using rolling contact parts or sliding contact parts can be further extended.
[0028]
The method for producing a rolling / sliding contact component according to the invention of claim 5 is: C0.80 to 1.20 mass%, Si0.15 to 0.70 mass%, Mn0.25 to 1.15 mass%, Cr0.90 1. In a thrust life tester represented by the following formula (i) of a rolling bearing using steel that includes a balance of Fe and unavoidable impurities, including 1.6% by mass and Mo of 0.25% by mass or less . Estimated L ₁₀ Processed rolling and contact part material formed into a predetermined shape from a bearing steel having a life of 10 ⁷ or less is subjected to 3 hours at 840 to 870 ° C. in a carburizing atmosphere having a carbon potential of 1.2% or more. quenched after being subjected to carburizing treatment by heating or, followed by subjecting the sub-zero treatment, and the total carbon content of the surface layer portion ranging from the surface to a depth of 0.5 mm 1.0 to 1.6 mass% In addition, the amount of dissolved carbon in the matrix of the surface layer portion is set to 0.6 to 1.0% by mass, spherical carbide is precipitated on the surface layer portion, and the amount of the spherical carbide is 5 to 20% by area ratio, and The particle size is 3 μm or less, and the surface hardness of the surface layer is 67 to 69 in terms of Rockwell C hardness.
[0029]
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass%
In the invention of claim 5, the reason for limiting each numerical value in the carburizing process is as follows. Incidentally, the total carbon content of the surface layer portion, the solid solution carbon content in the matrix of the surface layer portion, the amount of globular carbides in the surface portion, For the surface hardness of the particle size and the surface layer portion of the globular carbides in the surface layer portion, reasons for limiting the claims is the same as in the invention of claim 1.
[0030]
Carbon potential in the carburizing atmosphere This carbon potential is limited to 1.2% or more. When the carbon potential is less than 1.2%, it is hardly carburized with respect to the bearing steel having a carbon content of about 1% by mass. This is because the hardness of the surface layer portion and the area ratio of the carbide cannot be made desired, and the carbide cannot be refined.
[0031]
Carburizing temperature This temperature is limited to 840-870 ° C. If the temperature is less than the lower limit, the necessary carburization as described in the carbon potential cannot be performed. This is because the strength is lowered due to the precipitation of giant carbides as well as the increase in the thickness. That is, since the yield strength is proportional to the -1/2 power of the crystal grain size, the strength decreases when the crystal grain size becomes too large.
[0032]
Carburizing time This time is limited to 3 hours or more because the carburizing depth is insufficient when it is less than 3 hours.
[0033]
In the invention of claim 5 , the sub-zero treatment is preferably performed by cooling to −50 to −100 ° C. for 1 hour or more.
[0034]
According to the invention of claim 5 , since the material made of bearing steel often used for bearings is used, the material cost is reduced. Moreover, since the carburizing temperature is 840 to 870 ° C., the carburizing process is rapidly cooled after the carburizing process and then the sub-zero process is performed, so that the heat treatment cost is reduced. Therefore, the total manufacturing cost of the bearing parts is reduced. Further, it quenched after carburization, then since subjected to subzero treatment, it is possible to make the surface hardness of the surface layer portion to the HRC 67 to 69. Therefore, it is possible to extend the life of the rolling contact part or the sliding contact part. Among bearing steels, JIS SUJ2 is particularly mass-produced, and therefore, using it is preferable because the material cost is extremely low.
[0035]
In the invention of claim 5 , the carbon potential is preferably set to 1.2 to 1.4%. This is because if the carbon potential exceeds 1.4%, a large amount of soot is generated.
[0036]
Furthermore, in the invention of claim 5 , the heating time is preferably set to 3.5 to 5 hours. This is because if the heating time exceeds 5 hours, the heat treatment cost increases and the carbides become enormous.
[0037]
The manufacturing method of the rolling and sliding contact component according to the invention of claim 6 is as follows: C0.80 to 1.20 mass%, Si0.15 to 0.70 mass%, Mn0.25 to 1.15 mass%, Cr0.90 1. In a thrust life tester represented by the following formula (i) of a rolling bearing using steel that includes a balance of Fe and unavoidable impurities, including 1.6% by mass and Mo of 0.25% by mass or less . Estimated L ₁₀ Processed rolling and contact component material formed into a predetermined shape from a bearing steel having a life of 10 ⁷ or less is set to 1 at 930 to 970 ° C. in an atmosphere having a carbon potential of 0.9 to 1.1%. After the treatment for dissolving the existing carbide in the matrix by heating for more than an hour, it is rapidly cooled, and then at 840 to 870 ° C. in an atmosphere having a carbon potential of 1.2% or more. Quenched after being subjected to carburizing treatment by heating or while, followed by applying a sub-zero treatment, the total carbon content of the surface layer portion ranging from the surface to a depth of 0.5 mm 1.0 to 1.6 mass% In addition, the amount of solid solution carbon in the matrix of the surface layer portion is set to 0.6 to 1.0 mass%, spherical carbide is precipitated on the surface layer portion, and the amount of the spherical carbide is 5 to 20% by area ratio. and its particle size and 3μm or less, and further characterized by the at 67-69 Rockwell C hardness of the surface hardness of the surface layer portion.
[0038]
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass%
In the invention of claim 6, the reason for limiting each numerical value in the heat treatment is as follows. Incidentally, the total carbon content of the surface layer portion, the solid solution carbon content in the matrix of the surface layer portion, the amount of globular carbides in the surface portion, For the surface hardness of the particle size and the surface layer portion of the globular carbides in the surface layer portion, reasons for limiting the claims is the same as in the invention of claim 1.
[0039]
The process of dissolving the existing carbide in the matrix The carbon potential in the atmosphere in this process is limited to 0.9 to 1.1%, so that no carburization or decarburization occurs on the rolling contact parts or sliding contact parts. Because. If it exceeds 1.1%, carburization occurs with respect to the bearing steel having a carbon content of about 1% by mass, and if it is less than 0.9%, decarburization occurs.
[0040]
The reason why the heating temperature in this step is limited to 930 to 970 ° C. is that if it is less than 930 ° C., the solid solution of the carbide as the second phase existing after the spherical annealing is insufficient in the matrix, 970 ° C. This is because exceeding the range may cause fire cracking.
[0041]
Furthermore, the reason for limiting the heating time in this step to 1 hour or more is that if it is less than 1 hour, solid solution of the carbide as the second phase existing after the spherical annealing becomes insufficient in the matrix. is there.
[0042]
Carburizing process The carbon potential in the atmosphere in this process is limited to 1.2% or more. If it is less than 1.2%, the carburizing steel is hardly carburized if the carbon content is about 1% by mass. This is because the hardness of the surface layer portion and the area ratio of the carbide cannot be made desired, and further, the carbide cannot be refined. Note that the upper limit of the carbon potential is preferably 1.4% or less in order to prevent the generation of a large amount of soot.
[0043]
The reason why the heating temperature in this step is limited to 840 to 870 ° C. is that if it is less than the lower limit value, the necessary carburization as described in the carbon potential cannot be performed. This is because the strength is lowered due to the precipitation of giant carbides as well as the increase in the thickness. That is, since the yield strength is proportional to the -1/2 power of the crystal grain size, the strength decreases when the crystal grain size becomes too large.
[0044]
Furthermore, the reason for limiting the heating time in this step to 3 hours or more is that if it is less than 3 hours, the required carburization depth cannot be obtained.
[0045]
In the invention of claim 6 , the sub-zero treatment is preferably performed by cooling to −50 to −100 ° C. for 1 hour or more.
[0046]
According to the invention of claim 6 , since the material made of bearing steel often used for bearings is used, the material cost is reduced. Therefore, the total manufacturing cost of the bearing parts is reduced. Moreover, the existing carbide carburized after performing processing to dissolve in the matrix, since further subjected to subzero treatment, it is possible to make the surface hardness of the surface layer portion to the HRC 67 to 69. Therefore, it is possible to extend the life of the rolling contact part or the sliding contact part. Among bearing steels, JIS SUJ2 is particularly mass-produced, and therefore, using it is preferable because the material cost is extremely low.
[0047]
In the inventions of claim 1, claim 5 and claim 6 , the depth from the surface on which the maximum shear stress acting as a factor of internal origin peeling acts depends on the contact conditions, but in many rolling and sliding contact parts. It is up to about 0.5 mm. And, within this range, the strength is improved by making the total carbon amount, the solid solution carbon amount in the matrix, the amount of spherical carbide, and the surface hardness as described above, and as a result, the predetermined purpose is achieved. It is .
[0048]
Since the bearing steel used in claims 5 and 6 is a low-cleanness product and can be obtained at low cost, the manufacturing cost of rolling contact parts or sliding contact parts is reduced. Moreover, according to the method of the invention of claim 5 or 6 , even if such a low cleanliness product is used, a rolling contact component or a sliding contact component having desired performance can be manufactured.
[0049]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described below together with comparative examples.
[0050]
Examples 1-2 and Comparative Examples 1-3
A steel (JIS SUJ2) containing 1.01% by mass of C, 0.24% by mass of Si, 0.36% by mass of Mn, 1.46% by mass of Cr, 0.01% by mass of Mo, and the balance Fe and inevitable impurities, The inner ring material used for the rolling bearing of model number 6206 was formed using steel having an estimated L ₁₀ life (L _10e ) of 10 ⁷ or less.
[0051]
Subsequently, these inner ring materials were subjected to heat treatment under the following heat treatment conditions to produce inner rings (Examples 1-2 and Comparative Examples 1-3).
[0052]
Heat treatment condition 1 is that heating is performed at 850 ° C. for 3.5 hours in an atmosphere having a carbon potential of 1.3%, followed by oil cooling to 80 ° C., followed by cooling at −75 ° C. for 1 hour to perform sub-zero treatment ( Example 1).
[0053]
The heat treatment condition 2 was that heating was performed at 950 ° C. for 2 hours in an atmosphere having a carbon potential of 1.1%, then oil cooling was performed to 80 ° C., and then heating was performed at 850 ° C. for 3.5 hours in an atmosphere having a carbon potential of 1.3%. Thereafter, the oil is cooled to 80 ° C. and then cooled to −75 ° C. for 1 hour to perform sub-zero treatment (Example 2).
[0054]
Heat treatment condition 3 is to heat at 850 ° C. for 0.7 hours in an atmosphere with a carbon potential of 0.6% and then oil-cool to 80 ° C. (Comparative Example 1).
[0055]
Heat treatment condition 4 is to heat in an atmosphere with a carbon potential of 1.3% for 3.5 hours and then oil-cool to 80 degrees (Comparative Example 2).
[0056]
The heat treatment condition 5 was that heating was performed at 950 ° C. for 2 hours in an atmosphere having a carbon potential of 1.1%, then oil cooling was performed to 80 ° C., and then heating was performed at 850 ° C. for 3.5 hours in an atmosphere having a carbon potential of 1.3%. Thereafter, the oil is cooled to 80 ° C. (Comparative Example 3).
[0057]
In any of the above-described heat treatment conditions 1 to 5, a tempering treatment is performed in which heating is finally performed at 160 ° C. for 2 hours.
[0058]
The surface hardness (HRC) of the raceway surface of these five types of inner rings, the total carbon content of the outermost track surface, the amount of solute carbon in the matrix of the outermost track surface, the amount of spherical carbide deposited on the outermost track surface (area ratio) the maximum particle diameter of the spherical carbide precipitated in the track outermost surface, the amount of residual austenite at the position of depth 50μm from the surface (gamma _R content), compressive residual stress at a depth of 50μm from the surface are shown in Table 4 Street.
[0059]
[Table 4]

[0060]
Evaluation Test A ball bearing of model number 6206C3 was assembled by combining the inner rings of Examples 1-2 and Comparative Examples 1-3 with outer rings and balls made of JIS SUJ2 and subjected to normal carbonitriding. These ball bearings were used, and life tests were performed using a lubricating oil mixed with foreign matter and a clean lubricating oil. Table 5 shows the test conditions in the case of using the lubricating oil mixed with foreign matters, and the test conditions in the case of using the clean lubricating oil are the ones excluding the foreign matters.
[0061]
[Table 5]

[0062]
The testing machine shown in Table 5 can simultaneously test two ball bearings, and the radial load in Table 4 means the radial load of one ball bearing.
[0063]
The results of the life test are also shown in Table 4.
[0064]
The L ₁₀ life in Table 4 is expressed with reference to 1 in the case of Comparative Example 1.
[Brief description of the drawings]
1 is a graph showing the maximum inclusion distribution line of Table 4 obtained from Table 2. FIG.
FIG. 2 is a graph showing a relationship between an estimated L ₁₀ life and an actual L ₁₀ life.

Claims (6)

C0.80 to 1.20 mass%, Si 0.15 to 0.70 mass%, Mn 0.25 to 1.15 mass%, Cr0.90 to 1.60 mass%, Mo 0.25 mass% or less, the balance A steel comprising Fe and inevitable impurities, and comprising a bearing steel having an estimated L ₁₀ life of 10 ⁷ or less in a thrust life tester represented by the following formula (i) of a rolling bearing using this steel , When the treatment is performed, the total carbon content of the surface layer portion in the range from the surface to a depth of 0.5 mm is 1.0 to 1.6 mass%, and the solid solution carbon amount in the matrix of the surface layer portion is 0.6 to 1.0% by mass, spherical carbides are deposited on the surface layer part, the amount of the spherical carbides is 5 to 20% by area ratio, and the particle size is 3 μm or less, The surface hardness of the surface layer is Rockwell C hardness Rolling and sliding contact parts characterized by being 67-69.
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass% The rolling and sliding contact component according to claim 1, wherein the amount of the spherical carbide is 5 to 15% in terms of area ratio . The rolling / sliding contact component according to claim 1, wherein the amount of the spherical carbide is 10 to 20% by area ratio and the particle size is 2 μm or less . The rolling / sliding contact component according to any one of claims 1 to 3, wherein the amount of retained austenite in the surface layer is 5 to 20 vol %, and the compressive residual stress is 100 MPa or more . C0.80 to 1.20 mass%, Si 0.15 to 0.70 mass%, Mn 0.25 to 1.15 mass%, Cr0.90 to 1.60 mass%, Mo 0.25 mass% or less, the balance It is a steel made of Fe and inevitable impurities, and a rolling bearing using this steel has a predetermined shape from a bearing steel having an estimated L ₁₀ life of 10 ⁷ or less in a thrust life tester represented by the following formula (i) : The processed rolling and contact component materials formed in the above are carburized by heating at 840 to 870 ° C. for 3 hours or more in a carburizing atmosphere with a carbon potential of 1.2% or more, and then rapidly cooled, and then sub-zero. By performing the treatment, the total carbon content of the surface layer in the range from the surface to a depth of 0.5 mm is set to 1.0 to 1.6% by mass, and the amount of dissolved carbon in the matrix of the surface layer is 0. 6-1.0 mass%, spherical carbide is precipitated on the surface layer portion, the amount of the spherical carbide is 5-20% by area ratio and the particle size is 3 μm or less, and the surface hardness of the surface layer portion is A method for producing a rolling / sliding contact component, wherein the Rockwell C hardness is 67 to 69 .
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass% C0.80 to 1.20 mass%, Si 0.15 to 0.70 mass%, Mn 0.25 to 1.15 mass%, Cr0.90 to 1.60 mass%, Mo 0.25 mass% or less, the balance It is a steel made of Fe and inevitable impurities, and a rolling bearing using this steel has a predetermined shape from a bearing steel having an estimated L ₁₀ life of 10 ⁷ or less in a thrust life tester represented by the following formula (i) : A process in which the existing carbides are dissolved in the matrix by heating the processed rolling and contact part material formed on the substrate at 930 to 970 ° C. for 1 hour or more in an atmosphere having a carbon potential of 0.9 to 1.1%. quenched after being subjected to, then quenched after being subjected to carburizing treatment by heating for 3 hours or more at eight hundred and forty to eight hundred and seventy ° C. in a carbon potential of 1.2% or more atmosphere, with By performing sub-zero treatment, the total carbon content of the surface layer portion ranging from the surface to a depth of 0.5mm while the 1.0 to 1.6 wt%, the solid solution carbon content in the matrix of the surface layer portion 0.6 to 1.0 mass%, spherical carbide is precipitated on the surface layer portion, the amount of the spherical carbide is 5 to 20% by area ratio, and the particle size is 3 μm or less, and the surface hardness of the surface layer portion is further reduced. A method for producing a rolling and sliding contact component, wherein the thickness is 67 to 69 in terms of Rockwell C hardness.
L _10e = 26.18011 · EXP {−0.532 · F ₁ * (x ₁ , x ₂ )
−0.143 · F ₂ * (x ₃ , x ₄ ) −0.503 · F ₃ * (x ₅ )} (i)
here,
F ₁ * (x ₁ , x ₂ ) :( x ₁ · x ₂ −0.011435) /0.004731
_{F 2 * (x 3, x} 4) :( x 3 · x 4 -0.027895) /0.013278
F ₃ * (x ₅ ) :( x ₅ −0.002646) /0.001503
x ₁ : O content, mass%
x ₂ : Predicted maximum diameter of oxide inclusion, μm
x ₃ : Ti content, mass%
x ₄ : Predicted maximum diameter of titanium inclusion, μm
x ₅ : S content, mass%

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