Effect of Heat Treatments on Fatigue Failure and Fracture Toughness of Various Tool Steels - A Review

Abstract

In manufacturing industries, tools can be exposed to various loading condition like mechanical, tribological and environmental condition. So it is very important to enhance the material properties especially fatigue strength and fracture toughness, to increase the life of the tools and decreasing the production cost. Various heat treatments like hardening, tempering and cryogenic treatments are used to increase the wear resistance and the mechanical properties of the tool steels. This paper will present the state of the art review on the effect of the various heat treatments on fatigue strength and fracture toughness of the different tool steels. The different researchers used the experimental tests like thermal fatigue test, thermo- mechanical fatigue (TMF) test for calculation of fatigue strength and three- point bend tests for fracture toughness of the tool steels. Cryogenic treatment improves fracture toughness and fatigue strength of tool steels. Thermal fatigue resistance depends on initial material hardness. H13 steel at 49 HRC shows better thermal fatigue resistance than at 36 HRC. The tools and dies used in the industrial application in the metal forming industry usually fail due to the thermal fatigue failure. It is observed that the fatigue crack is the first indication of the failure of the dies. It is found that the cryogenic treatment will give better results in terms of the fracture toughness and fatigue strength for many types of the tool steels.