Study on fracture evaluation in hydrogen environment in 316L stainless steel used in high pressure hydrogen tank

In today’s growing pollution, hydrogen fuel vehicles are an important alternative to electric vehicles. For Type-4 Hydrogen Tank, a steel boss is normally used for valve mounting. The process of hydrogen embrittlement on steel plays a detrimental role. So, studies on the effect of hydrogen embrittlement on the threaded part of 316L stainless steel boss required for fastening of the valve for the 70 MPa compressed H2 tank have been carried out. For analysis, HEDE mechanism and Paris-Erdogan Law are used. For different values of initial crack length, the critical crack lengths are obtained for a particular loading cycle. The same calculation is repeated for different loading cycles. The analysis result shows that the critical crack length increases with the number of loading cycles. The critical crack length is higher 2% to 4% if the effect of hydrogen embrittlement is taken into account. So, for high pressure hydrogen tanks it is essential to consider the effect of hydrogen embrittlement.