Formation of Structure and Properties of 30HGSN2A Steel at Technological Stages of Manufacture of Heavy-Loaded Parts

Abstract

The cases of premature failure of the barrel of liquid damper, made of complex alloyed high-strength 30HGSN2A steel, are analyzed. The options failure and the causes of their occurrence are established. Fatigue failure of the barrels during an operation is due to the failure of the chrome coating of the rod and the appearance of scorings on the surface of the barrel. Cases of failure of the barrels during official tests are associated with the reduced hardenability and an increased tendency to decarburize steel in the bottom of the barrel, due to the increased nitrogen content here (due to segregation). The influence treatment conditions on the structure and properties of steel are investigated. Modes of dehydration and final heat treatment of the products to eliminate their premature failures are recommended. The proposed conditions, in particular, include increasing the dehydration temperature to 200-230 oС, reducing the exposure time at the hardening temperature and reducing the tempering temperature, using vacuum heating.