Accelerated Carbide Spheroidisation and Refinement in Spring Steel 54SiCr6

Abstract

Reduction of processing time is the goal of every business. In some cases, speeding up manufacturing processes is impossible or takes place at the expense of quality. The purpose of soft annealing is to obtain globular carbides in the microstructure. However, it is one of the most time-consuming heat treatment operations. Even its optimised versions require several hours of time. "Accelerated Carbide Spheroidisation and Refinement" (ASR) is an alternative process which can be performed using induction heating or thermomechanical treatment. It only takes several minutes to complete and has a beneficial effect on resultant mechanical properties. In this experiment, the impact of various microstructures in 54SiCr6 spring steel on hardening behaviour was explored. For this purpose, specimens with two different microstructures containing spheroidised carbides were produced by ASR accelerated annealing and by conventional soft annealing. Another initial microstructure, with lamellar pearlite, was obtained by hot rolling. It was found to have a certain effect as well. Quenched and tempered microstructures were observed using electron microscopy (SEM). Their mechanical properties were measured. The effects of various initial microstructures on resultant mechanical properties after cryogenic treatment were studied as well.