Effect Of Ce On Microstructure And Mechanical Properties Of H13 Steel

The carbon content of H13(4Cr5Mo Si Vl) steel was only 0.37~0.42%, but the high alloy content made the eutectoid composition point lower and made the H13 steel a eutectoid steel. The H13 as a kind of forging die steel models hot die steel, had excellent harden ability, red hardness, good toughness and high temperature performance. But the strength and toughness of H13 steel were reduced seriously because of forming a large number of the coarse eutectoid carbide,producing a continuous mesh distribution on the grain boundaries caused by the segregation of alloy elements during the solidification process. So it was an efficient method to improve H13 steel comprehensive performance by grain refinement, reducing carbides and changing carbide morphology.This paper studied the effect of add rare earth Ce to H13 steel. Grain boundary was purified and the shape of inclusions was changed after rare earth Ce was added into H13 steel.At the same time the size and quantity of inclusions were effectively controlled. But when there was too much rare earth Ce in the steel,it would produce a large number of rare earth inclusions,which reduced the wear resistance and mechanical properties of H13 steel. With the increase of the rare earth content in steel,the wear resistance of H13 steel improved gradually. But when the rare earth content in steel is more than 0.35%,the wear resistance of H13 steel slightly decreased. H13 steel with rare earth Ce element of 0.35%in mass fraction had the best wear resistance. The strength and ductility of H13 steel were obviously improved, due to the addition of proper amount of rare earth Ce could effectively refine grain size,modify inclusions and purify grain boundary. H13 steel with rare earth Ce element of 0.35% in mass fraction had the best comprehensive mechanical properties.Heat-treatment results show that the best heat treatment for the sample which is added proper amount of rare earth Ce is quenching at 1035℃, first tempering at 580℃, second tempering 560℃, and each tempering last for 2 hours to get high strength and better ductility. With this heat treatment better grain size,more homogeneous chemical compositions and better wear resistance can be got.After forging processing, the grain of H13 steels are obviously enhanced, and eutectoid carbide is obviously reduced. This suggests that it is hard for common casting process with rare earth Ce and heat treatment to replace forging process.