摘要：本文以抗拉强度为2700MPa的CM400马氏体时效钢为研究对象，将理论弹性应力集中系数（Kt）为2的缺口试样进行应力比（R）为0.1的轴向高频疲劳试验。通过成组法确定循环周次为107的条件疲劳极限为243MPa（应力幅），而通过喷丸的方式将疲劳极限提高了48%,并对喷丸前后的试样断口进行了扫描电镜观察和分析。实验结果表明：CM400在疲劳载荷下对缺口非常敏感，疲劳缺口系数基本等于Kt值，喷丸能有效地提高疲劳强度。扫描电镜观察发现：未经喷丸的试样全部从表面加工刀痕萌生裂纹，而经过喷丸处理后有一部分试样从内部夹杂萌生裂纹；疲劳裂纹扩展区、瞬断区的分界不明显，断口源区的形貌呈羽毛状，扩展区和瞬断区内都以穿晶开裂为主，伴有少量的塑性沿晶断裂。

　　关键词：马氏体时效钢，高频疲劳，疲劳极限，喷丸，疲劳断口。
 

The effect of shot peening on fatigue properties of CM400 maraging steel

Duan QiQiang1, Zhang ZheFeng1, Yao Ge1, Wang ZhongGuang1, Wang Wei1, Shan YiYin1, Yang Ke1, Hao Yao2, Yu JiaQing2

1（Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）

2（Bosch （China） Investment Ltd., Shanghai, 200120）

　　Abstract: The axial high frequency fatigue experiment of CM400 maraging steel with the ultimate tensile strength of 2700MPa was carried out, theoretical stress concentration factor （Kt） of notch specimens was 2, stress ratio （R） was 0.1. Fatigue limit at 107 cycles was 243MPa （stress amplitude） identified by group method, whereas shot peening treatment made fatigue limit increase 48%. At the same time, fracture morphology of specimens before and after shot peening was observed and analyzed by scanning electron microscopy （SEM）。 The experimental results showed that CM400 was very sensitive to notch under fatigue loading, fatigue notch factor was nearly equal to Kt, but shot peening could efficiently improve fatigue strength. From SEM observation, it was revealed that fatigue crack initiation always originated from the surface of specimens before shot peening, but from interior inclusions after shot peening for a proportional specimens. The boundary between crack propagation region and rapid fracture region was unobvious, the morphology of crack initiation region was like feather, main fracture mode of propagation region and rapid fracture region was transgranular failure, accompanied by little plastic intergranular fracture.

　　Keywords: Maraging steel, High frequency fatigue, Fatigue limit, Shot peening, Fatigue fracture.

　　联系方式

　　段启强：qqduan@imr.ac.cn

责任编辑：赵泽南

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