摘要：本文以抗拉強度為2700MPa的CM400馬氏體時效鋼為研究對象，將理論彈性應力集中系數（Kt）為2的缺口試樣進行應力比（R）為0.1的軸向高頻疲勞試驗。通過成組法確定循環周次為107的條件疲勞極限為243MPa（應力幅），而通過噴丸的方式將疲勞極限提高了48%,并對噴丸前后的試樣斷口進行了掃描電鏡觀察和分析。實驗結果表明：CM400在疲勞載荷下對缺口非常敏感，疲勞缺口系數基本等于Kt值，噴丸能有效地提高疲勞強度。掃描電鏡觀察發現：未經噴丸的試樣全部從表面加工刀痕萌生裂紋，而經過噴丸處理后有一部分試樣從內部夾雜萌生裂紋；疲勞裂紋擴展區、瞬斷區的分界不明顯，斷口源區的形貌呈羽毛狀，擴展區和瞬斷區內都以穿晶開裂為主，伴有少量的塑性沿晶斷裂。

　　關鍵詞：馬氏體時效鋼，高頻疲勞，疲勞極限，噴丸，疲勞斷口。
 

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.

　　聯系方式

　　段啟強：qqduan@imr.ac.cn

責任編輯：趙澤南

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