EFFECT OF CRYOGENIC TREATMENT ON MECHANI CAL PROPERTIES OF STEEL - A REVIEW

Steel is known for its strength and ductility. The contribution of strength and ductility adds to give steel greater values of toughness and resistance to shock. It is well known the properties of steel can be controlled by controlling its composition or by heat treatment. Steel is an alloy of iron with definite percentage of Carbon ranging from 0.15% - 1.5 %. These plain Carbon steels are classified on the basis of th eir Carbon content, as their major alloying element is Carbon steel with low Carbon content and has the same properties as iron i.e. soft but easily formed. As the Carbon content rises, the metal becomes harder and stronger but less ductile. Although the number of steel specifications runs into thousands, plain carbon steel accounts for more than 90% of the total steel output. The reason for its importance is that it is a tough, ductile and cheap material with reasonable casting, working and machining prop erties and also amenable to heat treatment to produce a wide range of properties.An effort has been made to review many research papers done by various researchers experimentedto alter the properties of steel group materials through various heat treatment processes particular effort has been made to study the effect of conventional, shallow and deep cryogenic heat treatment on mechanical properties of the medium Carbon steel group material. Influence of deep cryogenic processing in between quenching and tempering(QCT) on the Carbide precipitation, distribution of Carbide particles and the tribological behavior of a commercial steels and tool steel has been examined. The mechanical properties such as strength, hardness and wear resistance of the samples tr eated by quenching and tempering and QCT have been discussed. In the present paper, an attempt has been made to review the literature on metallurgical changes that occurred during the cryogenic treatment of steel group materials which is responsible for i mproving the mechanical properties by the transformation of retained austenite to martensite and precipitation of fine carbides