B对Fe-Ni基合金显微组织和抗氢性能的影响

EFFECTS OF B ON THE MICROSTRUCTURE AND HYDROGEN RESISTANCE PERFORMANCE OF Fe-Ni BASE ALLOY

利用金相显微镜、扫描电镜观察结合力学性能和抗氢性能测试研究了B对Fe-Ni基合金显微组织和抗氢性能的影响.结果表明:B的加入有效地抑制了时效过程中晶界上大量η(Ni_3Ti)相的析出,晶界上仅析出少量碳化物,从而显著提高了合金的塑性和抗氢性能.断口观察显示,对于无B合金,在由峰值时效到过时效处理的过程中,由于η相的长大,使合金发生由穿晶到沿晶断裂的转变;热充氢后,H在η/γ界面的积聚,促使合金发生大量沿晶断裂,而含B合金在热充氢后仍以穿晶断裂为主.

Effects of B on the microstructure and hydrogen resistance performance in an Fe--Ni base alloy were investigated by means of optical microscopy, scanning electron microscopy, thermal hydrogen charging experiments and tensile tests. The results show that abundant η（Ni3Ti） phases precipitate at grain boundaries （GBs） in the alloy without boron （FN） after aging treatment, while only a few carbides precipitate at GBs in the alloy with boron （FNB）. Tensile tests indicate that the FNB exhibites not only higher ductility but also lower hydrogen-induced ductility loss than those for FN alloy. Fracture observations show that the brittle intergranular fracture is the main feature of peak aging and over aging FN alloy and quite a few secondary cracks can be observed on fracture surface of the hydrogen charged samples due to the precipitation of η phase at GBs. However, the intragranular fracture is dominant feature for the FNB alloy whether hydrogen charging or not.