Effect of boron on the microstructure, mechanical properties and hydrogen performance in a modified A286

The microstructure, mechanical properties and hydrogen performance in a modified A286, with and without trace boron, were investigated in the present study. It was found that quite a few cellular η phases had precipitated at grain boundaries (GBs) in the modified A286 free of boron. However, a few carbides were the major precipitation phase in the modified A286 with boron and the cellular η phase was inhibited from precipitating at GBs. Thermal hydrogen charging experiment and tensile tests indicated that trace boron could not influence the strength of the modified A286 whether hydrogen charged or not, but significantly improve its ductility and alleviate its hydrogen damage because the precipitates at GBs had been changed from the cellular η phases to carbides. After aging treatment, the modified A286 with boron exhibited transgranular fracture whether hydrogen charged or not, however, intergranular fracture was easily to be formed in the modified A286 free of boron because the cellular η phases had precipitated at GBs.