α/γ相比例对HPD-1双相不锈钢疲劳性能的影响

Effect of α/γ phase ratio on fatigue performance of HPD-1 duplex stainless steel

通过对锻态HPD-1双相不锈钢进行不同温度的固溶处理,获得两相(α、γ)比例呈梯度变化的疲劳试样,在室温环境下测试对应相比例试样的疲劳断裂次数,获得相比例对疲劳性能的影响规律并进行微观分析。结果表明,在梯度范围内,随着α/γ比例提高,疲劳性能持续增强。对疲劳试样进行SEM、EDS与TEM分析得知,塑性变形主要发生在奥氏体内,位错以平面滑移型为主在奥氏体中大量增殖发展并在相界处塞积,铁素体内基本无位错发展,微裂纹形核于奥氏体区域并沿相界向外拓展,导致疲劳断裂。

Forged HPD-1 duplex stainless steel specimens were subjected to solution treatment at different temperatures in order to gain fatigue test samples with gradient changes of the ratio of the two phases(α, γ). The influence of phase ratio on fatigue performance and analysis of microstructure were obtained by comparing fatigue fracture times of the corresponding samples tested at room temperature. The results indicate that within the range of the ratio of the two phase, as α/γ ratio increasing, fatigue performance sustainably developed. According to the image of SEM, result of EDS and TEM image and diffraction pattern, plastic deformation mainly occurs in the austenite, and the dislocations are primarily plane-slip type, which massively multiply in the austenite and pile up at the phase boundary, but dislocation motion scarcely happens in ferrite. Besides, microcracks nucleate in the austenite region and expand outward along the phase boundary. Under the combined effect of these factors, fatigue fracture finally occurs.