微观组织对GCr15轴承钢氢扩散行为的影响

Effect of microstructure on hydrogen diffusion behavior of GCr15 bearing steel

通过对球化退火态、球化退火+淬回火(Q&T)态GCr15轴承钢进行电化学氢渗透试验来描述氢扩散行为,并分析了微观组织以及热处理状态对氢扩散行为的影响。结果表明,对于球化退火态试样,碳化物的分布情况对氢扩散行为影响很大。氢在带状碳化物中扩散最快,而沿晶界分布的网状碳化物作为氢陷阱,可以捕捉更多的氢原子。Q&T试样中,氢在带状未溶碳化物中扩散最快,且随着残留奥氏体体积分数的增大,有效氢扩散系数减小。球化退火试验钢的氢扩散系数远高于Q&T钢。Q&T试样中残留奥氏体的存在使氢陷阱增加,导致氢的渗透更难进行。

Electrochemical hydrogen permeation test of spheroidizing annealed,spheroidizing annealed+quenched and tempered(Q&T)GCr15 bearing steel was carried out to describe hydrogen diffusion behavior.The effects of microstructure and heat treatment status on hydrogen diffusion behavior were analyzed.The results show that the distribution of carbides in the spheroidizing annealed specimens has a greater effect on hydrogen diffusion behavior.Hydrogen diffuses fastest in banded carbides,while the network carbides along grain boundaries acts as hydrogen traps,trapping more hydrogen atoms.In the Q&T specimens,hydrogen diffuses fastest in banded undissolved carbides.The effective hydrogen diffusion coefficient decreases with the increase of the volume fraction of retained austenite.The hydrogen diffusion coefficient of the spheroidizing annealed tested steel is much higher than that of the Q&T steel.The number of hydrogen traps in Q&T specimens increases due to the presence of retained austenite,making hydrogen permeation more difficult.