滲碳M50NiL鋼磨削表面完整性特征及疲勞失效機理

滲碳M50NiL鋼磨削表面完整性特征及疲勞失效機理Surface Integrity Characteristics and Fatigue Failure Mechanism of Carburized M50NiL Steel

用光學(xué)顯微鏡、掃描電子顯微鏡（SEM）、原子力顯微鏡（AFM）、顯微硬度計、殘余應(yīng)力測定儀，分析研究滲碳M50NiL鋼普通磨削和精密磨削兩種工藝的表面完整性特征，通過旋轉(zhuǎn)彎曲疲勞實驗實測兩種試樣的疲勞性能，并對疲勞實驗結(jié)果進行模擬分析。結(jié)果表明：在不考慮表面加工缺陷的理想情況下，滲碳M50NiL鋼旋轉(zhuǎn)彎曲疲勞裂紋在亞表面起源；普通磨削產(chǎn)生的表面應(yīng)力集中，將疲勞源從亞表面移至表面；精密磨削通過優(yōu)化磨削工藝改善了表面變質(zhì)層特征，有效抑制了加工表面應(yīng)力集中敏感，將疲勞源從表面回歸至亞表面；旋轉(zhuǎn)彎曲疲勞壽命最高可提高30倍，平均提高15倍。

The surface integrity of carburized M50NiL steel was studied by optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), microhardness tester and residual stress tester. The fatigue properties of the two specimens were measured by the rotational bending fatigue test, and the fatigue test results were simulated and analyzed. The results show that the rotation bending fatigue of carburized M50NiL steel is originated in the sub-surface in the ideal case without considering the surface processing defects. The surface stress concentration factor produced by general grinding causes the fatigue source to be moved from the surface to the sub-surface. Precise grinding improves the surface quality by optimizing the grinding process, effectively restrains the stress concentration of the working surface, and returns the fatigue source from the surface to the sub-surface. The maximum rotary bending fatigue life can be increased by 30 times and the average is 15 times.

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