Experimental and Numerical Analysis of Hydrogen-Induced Effects in ASTM A131 and A36 Steels for Naval Fuel Systems

Hydrogen embrittlement (HE) can degrade the mechanical integrity of steel pipes, increasing failure risks in naval fuel systems. This study assesses HE effects on ASTM A131 and A36 steels through tensile testing and numerical modeling. Tests at different hydrogen exposure times showed that A131 outperformed A36 in mechanical strength. However, both materials experienced property degradation after 6 hours. At 9 hours, a transient increase in strength occurred, due to temporary microstructural hardening, though the overall trend remained a decline. A131 and A36 exhibited maximum reductions in ultimate tensile strength of 19% and 47%, and in toughness of 39% and 61%, respectively. Additionally, microstructural analysis revealed the presence of inclusions, intergranular decohesion and micro-crack, in specimens exposed for longer periods. Finally, a combined GTN-PLNIH numerical model was implemented, demonstrating its effectiveness in predicting the mechanical behavior of structures exposed to hydrogen.