Study of the Metal Properties and Structure of a Large Shell Made of 15Kh2MFA Steel

Mechanical properties and structure are studied for metal of a large test workpiece of steel 15Kh2MFA-A mod.B with a wall thickness under heat treatment of 670 mm. Special attention is devoted to studying the grain structure since the amount of austenitic grains, in particular, grain size, have a significant effect on impact strength and critical brittleness temperature, i.e., important properties for reactor body workpiece metal quality. A unique combination is obtained for strength properties and brittle failure resistance of workpieces for water-water reactor (VVER) bodies. The possibility is demonstrated of significant expansion with respect to thickness of the existing range of reactor vessel workpiece bodies made of steel of type 15Kh2MFA with provision of a required set of mechanical properties laid down by existing technical documentation for a workpiece of smaller thickness, which creates the possibility of planning and preparation of contemporary VVER with increased safety during operation and an ultra long life.