Cryogenic heat treatment — a review of the current state

Kamran Amini,Sirus Javadpour,Amin Akhbarizadeh

doi:10.30544/238

Abstract

The deep cryogenic heat treatment is an old and effective heat treatment, performed on steels and cast irons to improve the wear resistance and hardness. This process includes cooling down to the liquid nitrogen temperature, holding the samples at that temperature and heating at the room temperature. The benefits of this process are significant on the ferrous materials, but recently some studies focused on other nonferrous materials. This study attempts to clarify the different behavior of some materials subjected to the deep cryogenic heat treatment, as well as explaining the common theories about the effect of the cryogenic heat treatment on these materials. Results showed that polymers exhibit different behavior regarding to their crystallinity, however the magnesium alloys, titanium alloys and tungsten carbide show a noticeable improvement after the deep cryogenic heat treatment due to their crystal structure.

Highlights

Cryogenic heat treatment was introduced to the industries in the 1920s
This special kind of supplementary heat treatment plays an important role in selecting the finishing production procedure of parts with the lowest wear rate, the lowest austenite percentage and the lowest economic cost. This specific heat treatment is classified into two different groups: (i) the shallow cryogenic heat treatment performed at temperatures higher than 125 K, and (ii) the deep cryogenic heat treatment attributed to the treatments in which samples are cooled down to lower temperatures (125–77 K)[1,2,3]
It was documented that different polymers show different behaviors, ranging from vivid improvement to vivid reduction in hardness and wear resistance, after the deep cryogenic treatment as a consequence of their crystal structure

Summary

Introduction

Cryogenic heat treatment was introduced to the industries in the 1920s This special kind of supplementary heat treatment plays an important role in selecting the finishing production procedure of parts with the lowest wear rate, the lowest austenite percentage and the lowest economic cost. These wandering carbon atoms jump to the neighboring sites and act as appropriate places for the eta chromium carbide nucleation in the prior tempering These new carbides increase the carbides percentage and make a more homogenous carbide distribution in the steel and cast iron materials after the deep cryogenic treatment [4, 6, 9,10,11,12,13,14,15,16]. In this study the deep cryogenic heat treatment of different materials including tungsten carbide, polymers and their composites, magnesium and titanium alloys, were reviewed to study the effect of this treatment and the theories about this phenomenon on these materials

Deep cryogenic heat treatment

Metallic materials

Conclusion