Study On The Influence Of Trace Elements On The Performance Of Chromium-Molybdenum Steel And Heat Treatment Process

In recent years,with the upgrading of large-scale machinery and equipment in China,the quality requirements of mechanical parts are getting higher and higher,so the performance requirements of materials are getting higher and higher.Chromium-molybdenum-carbon steel is a common material for mechanical parts.It has good overall mechanical and technologieal properties.It has been widely used in mechanical manufacturing,automotive and petrochemical industries.It is used to manufacture transmission shaft and fastener parts.With heat treatment,it has high hardness,toughness,plasticity and heat resistance.Different heat treatment processes have different effects on the properties of alloy steel.In this thesis,the effects of different heat treatment processes on the plasticity,toughness and strength of 35CrMo alloy steel were studied,and the optimum heat treatment parameters were obtained to improve the comprehensive properties.The effect of alloying element Ti on the properties of 35CrMo alloy steel was investigated,which provided theoretical basis for better application of chromium-molybdenum-carbon steel in mechanical manufacturing fields.The main contents of this paper are as follows:(1)35CrMo alloy steel was heat treated by changing the heating temperature,holding time and cooling mode of quenching and tempering.The microstructure and hardness of the steel after heat treatment were observed and analyzed by metallographic microscope,scanning electron microscope and hardness tester.The results showed that when the quenching temperature was 900?,the holding time of quenching was 60 minutes and when the tempering temperature was 500?,the holding time of tempering holding was 90 minutes,the structure and properties of 35CrMo alloy steel are the best.(2)For 42CrMo alloy steel,the annealing process is added on the basis of heat treatment process parameters in the factory,and the effects of different annealing,quenching and tempering temperatures on the structure and properties of 42CrMo alloy steel are studied.The 42CrMo alloy steel and Ti elements are remelted in vacuum arc smelting furnace to obtain samples,and the composition of samples is analyzed and scanned by X-ray diffraction and energy dispersive spectrometer.The mechanical properties of 42CrMo alloy steel were tested by hardness tester.It was found that the microstructure of 42CrMo alloy steel was refined and the mechanical properties such as plasticity and strength were improved after adding Ti elementThe new process of heat treatment combines the deformation of related materials with titanium element to produce new material combination.This new process can make materials have good properties and improve the application of metal materials in industry.Figure[25]table[15]references[97]...