Fracture strain of gun steel for ultra-high-pressure vessels considering triaxiality effect

To better understand the local failure of ultra-high-pressure vessels, the ductile fracture behavior of a gun steel, PCrNi3MoVA used for ultra-high-pressure vessel in China, was studied through experimental and numerical investigations. Tests on smooth and notched specimens of different notch radius values were performed, and the stress–strain states of specimens in the loading history were obtained through finite element analysis. Fracture was identified by means of comparing the engineering stress versus the strain obtained from tests with the finite element analysis results. The effect of triaxiality on the ductile fracture behavior of PCrNi3MoVA was discussed. Finally, a new plastic design-by-analysis method considering triaxiality effect was proposed to protect against local failure of ultra-high-pressure vessels.