37CrNi3MoVE钢不同加载速率下应力腐蚀行为的试验研究

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Experimental investigation on stress corrosion behavior of 37CrNi3MoVE steel in artificial sea- water was conducted under different constant displacement rates. Compact tensile （CT） specimens ma- chined from a high pressure gas bottle were used to study the stress corrosion crack growth properties. The relationships between load and crack length, crack growth rate and stress intensity factor were arrived. The results revealed that the displacement rate plays an important role on the trend of load and crack growth. In early crack growth region, the reached maximum load under displacement rate 5.0×10^-5 mm/s was higher 12.73% than that of under 1.0×10^-5 mm/s. After the cracks grow over 2 mm,the load capabili- ties under different displacement rate were consistent each other. For plane stress specimens in artificialseawater, the initial crack growth stress intensity factor of 37CrNi3MoVE steel was measured as approxi- mate 110 MPa ,fro-. The stable crack growth rate of 2.9 ×10^-5 mm/s and 8.2×10^-5 mm/s was appeared in specimens under displacement rates 1.0×10^-5 mm/s and 3.0×10^-5 mm/s respectively. However,no obvious stable crack growth rate was observed in the specimen with displacement rate of 5.0 ×10^-5 mm/s. Stress corrosion appears clearly under low displacement rate than that under high displacement rate.利用紧凑拉伸（CT）试样对水下高压气瓶用钢37CrNi3MoVE材料在模拟海水环境中进行了应力腐蚀试验研究,采用恒位移速率控制,试样为平面应力试样,获得了不同位移速率下载荷―位移曲线和裂纹扩展速率与应力强度因子关系曲线。结果表明,载荷与裂纹扩展速率增长趋势与加载速率密切相关,位移速率为5.0×10-5mm/s比1.0×10-5mm/s时裂纹扩展前期的最大载荷高12.73,裂纹扩展约2mm后,相同裂纹长度下能承受的载荷基本一致;该材料在海水环境中,平面应力状态下,裂纹起始扩展应力强度因子约?110MPam。位移速率为1.0×10-5mm/s和3.0×10-5mm/s时测得的裂纹扩展速率da/dt分别出现2.9×10-5mm/s和8.2×10-5mm/s的稳定扩展阶段,但位移速率为5.0×10-5mm/s时,da/dt与KⅠ的关系曲线没有明显稳定扩展阶段。位移速率低者比位移速率高的应力腐蚀明显。