α′马氏体对304不锈钢氢脆行为的影响

Effects of α′ martensite on hydrogen embrittlement of 304 stainless steels

304奥氏体不锈钢在预应变强化以及长期服役过程中容易发生应变诱导α′马氏体相变,而α′马氏体对304材料的氢脆敏感性影响较大,因此系统地研究α′马氏体体积分数与304不锈钢氢脆间的关系尤为重要。首先通过预变形(0%,10%,20%,30%)在304不锈钢中产生预先存在的α′马氏体,然后进行电化学充氢,最后进行慢应变速率拉伸实验将试样拉断。研究了预先存在的α′马氏体体积分数对充氢304不锈钢力学性能及氢扩散系数的影响,结果表明:304不锈钢的氢脆敏感性和氢扩散系数随着预先存在的α′马氏体体积分数的增加而增加,当预先存在的α′马氏体体积分数超过20%时,氢扩散系数提高了8倍。

304 stainless steels are easily to form strain-induced α′ martensite during prestrain process and long-term service period. Due to important influences of α′ martensite on hydrogen embrittlement (HE) susceptibility of 304 steels, it is of great significance to systematically study the relationship between α′ martensite content and HE. In this study, various degrees of prestrain (0%, 10%, 20%, 30%) were firstly created by tensile deformation in a series of specimens to form pre-existing α′ martensite. After electrochemical hydrogen charging, the specimens were then deformed to fracture by slow strain rate tension test. The effects of pre-existing α′ martensite on mechanical properties and hydrogen diffusion coefficient of 304 steels were studied. Experimental results indicated that the hydrogen diffusion coefficient and HE susceptibility increased with increasing volume fraction of the pre-existing α′ martensite. When the content of the pre-existing α′ martensite was higher than 20%, the hydrogen diffusion coefficient in 304 steels was increased by 8 times.