时效温度对18Ni350钢缺口效应和延迟断裂性能的影响

Influence of aging temperature on notch effect and delayed fracture behavior of 18Ni350 maraging steel

通过在空气中进行慢位移速率缺口拉伸试验研究了不同时效温度对18Ni350马氏体时效钢的缺口效应和延迟断裂行为的影响。结果表明,极限抗拉强度较低的420℃和450℃欠时效试样对缺口的敏感性较高,并表现出明显的延迟断裂敏感性。480℃时效试样的极限抗拉强度略低于510℃峰时效,但缺口抗拉强度高出100 MPa以上,因此480℃时效可降低缺口敏感性。540℃过时效试样的极限抗拉强度下降的同时缺口敏感性仍较高,但有益于降低延迟断裂敏感性。

Influence of different aging temperature on the notch effect and delayed fracture behavior of 18Ni350 maraging steel was studied by slow displacement rate notch tensile test in the air. The results show that under-aged samples which aged at 420 ℃ and 450 ℃ with the lower ultimate tensile strength have higher notch sensitivities and delayed fracture sensitivities. The notch sensitivity of the sample aged 480 ℃reduces due to its ultimate tensile strength is slightly lower than that of the peak-aged（ 510 ℃） sample and its notched tensile strength is more than 100 MPa over that of the peak-aged sample. The ultimate tensile strength at over-aged temperature（ 540 ℃） decreases and the notch sensitivity increases,however it is beneficial to reduce the delayed fracture sensitivity.