Effect of Boron on the Microstructure and Hydrogen Resistance Performance in Fe-Ni-Based Alloys

摘要

Effect of boron addition (0, 0.002, 0.006 and 0.01 wt.%) on the microstructure and hydrogen embrittlement (HE) sensitivity in an Fe-Ni austenitic alloy has been investigated. The results show that η phase has an incoherent interface with matrix and consist of dislocations in the alloy without boron. With 0.002 wt.% boron addition, the precipitation of r| phase is markedly retarded. Moreover, 0.01 wt.% boron addition will result in the minor amount of borides precipitation at grain boundaries. By performing the tensile test after hydrogen charging, it is revealed that the precipitation of η phase directly influences the HE resistance of alloy and has a detrimental effect on ductility. It is further shown that boron atoms compete with hydrogen atoms for site occupancy in matrix, which is probably responsible for reducing the deleterious embrittlement effects of hydrogen. And the presence of borides slightly increase HE sensitivity in the alloy with 0.01 wt.% boron.