Numerical Simulation Of Temperature Distribution In Electron Beam Welding And Heat Treatments Research Of M42/X32Bimetal Blade Saw

ABSTRACT:In this paper, we take M42/X32bimetal blade saw as the research object. By means of finite element simulation with the help of ANSYS software, effect of welding current and welding speed on the welding temperature field was studied. The optimized welding parameters were got, and the results were verified by experiment. By means of OM, SEM, TEM, DSC, XRD, high temperature metallography, mechanical measurement and hardness measurement, microstructure and properties of bimetal blade saw after heat treatments was studied, and the optimized quenching and tempering process was got. Evolution of microstructure and properties of welded joint under the optimized heat treatments process were also studied. Main conclusions were presented as followed:(1) When the welding current Ib increases from10to30mA or the welding speed V increases from0.5to8m/min, temperature field distribution becomes uniform gradually. Good weld seam is got when simulation parameter Ib is20mA and V is2m/min. Morphology of the simulated seam is in good agreement with that by experiment, and the calculation error of the weld width ranges from-3%to1.5%.(2) M42has a pronounced hardness of997HV annealed at800℃for4hours+quenched at1200℃for5minutes. When M42is annealed at800℃for4hours+quenched at1200℃for5minutes+tempered3times at620℃for4minutes, a large amount of tiny M2C are precipitated, leading a highest hardness of1014HV. The volume fraction of residual austenite in M42is only3.6%. Hardness, tensile strength and elongation of X32after the same heat treatments are375HV,1005MPa and13.2%respectively.(3) The weld has the characteristic of as-cast microstructure after welding. The hardness of the weld joint is larger than that of base metals on both sides, and the center of the weld owns a largest hardness of811HV. Fine and dispersed secondary carbides M23C6and M2C are precipitated in the weld joint after annealed at800℃for4hours+ quenched at1200℃for5minutes+tempered3times at620℃for4minutes, leading to a average hardness (908HV) of the weld joint. After heat treatments, Young’s modulus of the welding zone (200GPa) is higher than that before the heat treatments (176GPa).