Research On A New Type Of Bainitic Wear-resistant Cast Steel

Bainitic steel is a type of steel which matrix is bainite or bainite/martensite when it is in service-type. It has excellent cost performance, which made it's widespread availability in industrial application such as mechanical engineering, metallurgy, transportation and constructional material, etc.The workpieces which work in many environment such as mineral mountain and building and so on need good wear-resisting property. As a triditional wear resistant material, Hadfield steel has good wear-resisting property under high-impact load while it has poor wear-resisting property under low-impact load. For the high mass percent of alloy or complex heat treatment, homogengous bainitic steels do not have obvious advantage in economical efficiency, environmental protection and manipuility.A new type bainitic wear-resistant cast steel will will be exploided in this reasearch. It has medium alloy and only need easy-operating heat treatment. The experimental steel will be expect to have balanced hardness and impact ductility, excellent wear-resisting property under the low-impact load.The experimental steel's alloy contents 2.0wt%Si,3.0wt%Mn,0.4wt%Mo, 1.2wt%Cr and 0.002wt%B, and it has there three different content value of C: 0.25wt%,0.50wt% and 0.70wt%.After casting, test samples were run to heat treatment such as annealing, isothermal treatment and dry quenching, etc. Many properties such as hardness, impact ductility and relative wear resistance were tested. Meanwhile, this article also observed the metallurgical sructure and analysed wear machanics.The experiment results is as follows:1.Bainite will be acquired under as-cast and after heat treatment in experimental medium-alloy cast steel which regards the Si, Mn, Cr, Mo, B as the alloy elements. 2. The content of metallurgical structure(martensite, bainite and residual austenite) is the general influencing factor for hardness of experimental steels.Dry quenching is helpful for the acquisition of bainite andit can increase the impact ductility of experimental steels obviously.3.The chemical composition of experimental steel which has most excellent integrated mechanical property used in lab work is:0.70wt%C,2.0wt%Si, 3.0wt%Mn,0.4wt%Mo,1.2wt%Cr,0.002wt%B. The heat treatment for the steel is: insulating 60min on 900℃for austenizition and cooling in the air directly. The steel's performance parameter is:304.1HV;αK=40.81J/cm2; value of relative wear resistance with water-quenched Hadfield steel is 1.20.4. It can be concluded that the chief abrasion mechanism is worn by plastic deformation and the secondary is by minute wear-cutting by the furrow and pleat, and a small quantity of on the wear surface.