Performance Evaluation And Quench Methods Research Of Bi-metal Band Saw Blade Tooth Material HSS M42

In this paper, we selects some bi-metal saw blades produced by domestic and foreign companies, first, By means of OM, SEM, nano-indentation, a comparative study of bi-metal band saw blade teeth of M42high speed steel was carried out, then bi-metal band saw blade material performance evaluation system was established; And then, to improve the heat treatment system of M42high speed steel tooth material, By means of OM, AFM, XRD, high temperature metallurgical, high temperature hardness and other means, the influences of cooling methods and cooling rates on the microstructure and mechanical properties was systematically studied, according to the testing and analyzing, main conclusions were presented as followed:(1) A large number of irregular M2C carbide distributed in Bichamp’s M42steel, which is about5～9um of M2C, The dispersed M6C carbide particles distributed in Bichamp’s PM-M42steel, the size is not more than2um.carbide clusters exist in Conventional M42steel produced by Bichamp、Lenox、Simonds company in some areas. Carbide in M42steel from Bacho and Simonds company showed obvious zonal distribution.(2) M42high speed steel was tempered for600℃/1h/4times: Bichamp’s M42steel inversely reduced10.06%in the hardness, a lot of hot corrosion cracking and grain appeared around boundary carbides. PM-M42steel from Bichamp and M42steel from foreign companies reduced3.7%～5.3%in the hardness; M42steel and PM-M42at The tip of the teeth from Bichamp improved greatly,43.3%and22.3%in the Young’s modulus.two products produced by Bichamp have poor resistance to high temperature tempering stability.(3) Primary carbides unevenly distributed in M42steel, fine carbide particles was easy to assemble large-sized carbide, which began to dissolve at the quenching temperature of1170℃for300s, The dispersed carbide particles distributed in PM M42steel,which has excellent anti-gathering capability, began to dissolve partially at the quenching temperature of1205℃for70s. At the quenching temperature of1205℃ for300s, austenite grained abnormal growth sharply in Conventional M42steel; at1205℃for300s, grain boundary size of PM M42steel didn’t change significantly.(4) PM M42steel was annealed at840℃for4hours and quenched at1205℃for10minutes, When the cooling rate reached0.1℃/s<v≤0.25℃/s, Pearlite structure can be obtained; When the cooling rate reaches0.5～1℃/s, Pearlite structure and Bainite structure can be obtained, with increasing of the cooling rate, bainite increased largely and Pearlite decreases in amount. When the cooling rate reached4～10℃/s, bainite decreases in amount, quenched martensite appeared; with increasing to20℃/s of the cooling rate, bainite phase would be restrained, while the amount of quenched martensite in increased; When the cooling rate increased from0.1℃/s to20℃/s, hardness of tempered alloy increased from548HV to1012HV.(5) When M42high speed steel was quenched by medium of sand, fog, oil and water.Dimension of martensite reduced from150～200nm to30～60nm, and the content of secondary carbide precipitation on the twin boundary increases while the size decreased; while the content of retained austenite increased from7.6%to14.5%. Hardness of quenched alloy reduces from835HV to788HV; Hardness of tempered alloy increases from945HV to1002HV.temper resistance increased gradually, with Additional600℃/1h/4times tempering, hardness increases from856HV to924HV.