16Mn钢在不同条件下的疲劳行为研究

Study on fatigue behaviour of 16Mn steel under different condition

对截面为3 mm×3mm的16Mn钢试件在空气和3.5%NaCl溶液中分别进行疲劳试验,获此外,研究发现在空气中的弯曲疲劳极限σ?1与抗拉强度σb之间的关系为σ-1≈0.5σb。据此并得了S-N曲线,并对疲劳试样表面和断口形貌进行了观察。结果表明:与空气相比,3.5%NaCl腐蚀溶液使16Mn钢的疲劳强度显著降低;在空气中疲劳试样只有一个萌生于试样表面基体的裂纹源,而在3.5%NaCl溶液中一般有多个裂纹源,而大多数裂纹源均萌生于点蚀坑;空气中疲劳裂纹扩展区以疲劳辉纹为主,而在3.5%NaCl溶液中的腐蚀疲劳则以沿晶开裂等脆性特征为主。对空气中的疲劳极限进行了预测,预测值与试验值比较吻合,误差在10%以内。本文研究结果可为16Mn钢结构的设计和使用提供依据。

The fatigue behavior of 16Mn steel in air and 3.5% NaCl solution is studied by the fatigue tests.The S-N curves are obtained and the observations of specimen surfaces and fatigue fractographs are made.The results show that the fatigue strength of 16Mn steel in 3.5% NaCl solution is much lower than that in air.Fatigue cracks in air are initiated from the matrix of surface,while most of fatigue cracks in3.5% NaCl solution are initiated from pits.The typical feature of the fatigue crack propagation region in air is fatigue striations,while that in 3.5% NaCl solution is intergranular crack characteristic.There is empirical equation σ-1≈0.5σb between the fatigue limit(σ-1) in air and drag strength(σb).The fatigue limit in air can be predicted.The predicted fatigue limit is in agreement with the experimental fatigue limit.