Effect Of Adding ZrO 2 Nanopowder On Microstructure And Mechanical Properties Of Carbon Steel

Grain refinement is one of the important means to improve strength and toughness of iron and steel materials. By second-phase particles was dispersed evenly into liquid steel to add deformation center. The method of grain refining consist of internal precipitation method and external addition method. This paper study target is carbon section , by external adding ZrO₂ nanopowder to realize refine of grain.ZrO₂ nanopowder was prepared by liquid sedimentation method. Grain size is 40nm⁵0nm. This paper mainly studies the influence of adding different quality fraction(0.1%,0.3%,0.5%,0.7%,0.9%) ZrO₂ nanopowder on microstructure and mechanical properties of carbon steel.Test of steel in the same condition of smelting and rolling deformation, The grain refinement mechanism and its mechanical Properties were investigated by a series of analysis techniques such as optical microscope(OM), scanning electron microscope(SEM) and tensile performance test in detail.The conclusions of the present dissertation are as follows:(1) ZrO₂ nanopowder evenly into liquid steel by pre-dispersed method of the nano-particles;(2) the ZrO₂ nanopowder were used as deformation center and recrystallization in liquid steel casting solidification process and the rolling deformation proces- -s,compared with original steel,the grain become finer;(3)The quality fraction of ZrO₂ nanopowder is 0.3%, the steel grains were fined to 7.46μm, mechanical properties increased, the yield strength and tensile strength of 218.14Mpa and 401.31Mpa respectively.The integrating mechanical properties of the steel are increased obviously.