Study On Wear And High Temperature Oxidation Performance Of 4Cr4Mo2Ni MnSiV Hot-work Die Steel

With the development of mold industry at home and abroad,the service temperature and load of the mold material are also constantly improving,and the performance of the hot die steel also poses more stringent requirements.The 4Cr4Mo2NiMnSiV steel studied in this paper,as the steel for the insert mold,not only has good toughness,but also requires to have good high temperature wear resistance and oxidation resistance under high temperature and high pressure and high friction working conditions.performance.In this paper,by analyzing the impact of alloying elements on the material properties in order to design a new steel.The use of optical microscopy,scanning electron microscopy and tensile,impact testing machine and other analytical techniques to study the test material and mechanical properties of the organization,optimize the heat treatment process.At the same time,the high temperature wear and high temperature oxidation of the alloy steel were studied.The results of different heat treatment of as-cast alloy steel show that the hardness of the test steel is 53.8 HRC and the tensile strength and elongation are 1200 MPa and 4.5%respectively under the as-cast conditions.In the as-cast microstructure,the dendritic segregation is more serious.After the material is annealed at 830?for 5h and then cooled in the furnace,the hardness value is 32.5HRC.The microstructure of the alloy steel shows the finely distributed dendrites Carbide particles.The best single-liquid quenching and tempering process of alloy steel:Austenitizing at 1000?for 30min,oil quenching,tempering at590?for 2h,tempering twice,the hardness of this material is 53.6HRC,tensile strength is1544.6MPa,The rate of 7.22%;the best isothermal quenching+tempering process:950?austenitizing 30min,350?salt bath 3h,300?tempering 2h,twice tempering;at this time the material hardness 44.3HRC,tensile strength 1562.7Mpa,elongation of 8.45%.The study on the high temperature wear resistance of the alloy steel found that the hardness and microstructure of the alloy steel have certain influence on the wear rate and friction coefficient,and the martensite+bainitic complex phase has higher wear resistance.As the experimental temperature increases,the wear properties of the alloy steel also vary.The wear rate of the alloy steel is the largest at 200?and then decreases.A large number of fine particles exist on the wear surface under high temperature wear.XRD analysis shows that the main components are Fe₂O₃ and Fe₃O₄.The comparative test shows that the sample steel with martensite and bainite structure has the best wear resistance,followed by the horse Tensile steel,and H13 steel?C:0.4,Cr:5.15,Mo:1.45,V0.9,Si:1.04?wear resistance is lower than the test steel.The material were subjected to high temperature oxidation test at 600?and 700?for200h.The H31 steel had the least oxidation and weight gain per unit time,followed by the isothermal quenching alloy steel and the single-liquid quenched alloy steel.The results of XRD showed that the products of oxide layer were mostly Fe oxides when oxidized at 600?,and different kinds of Ni,Cr oxides and iron oxides appeared at the oxidation layer at 700?.