Effect Of Laser Heat Treatment On The Microstructures And Hardness Characteristics Of High Speed Steel Rolls

As rolling technology continues to improve in the rolling speed and degree of automation, the rolling production as an important field, its performance requirement will be higher. High-speed steel roll is important spare parts of consumption in rolling production, its wear resistance, strength and toughness will directly influence the quality level of the merits and costs. Study on surface structure and performance of high speed steel roll has important value in engineering application to improve quality and reduce the production cost, and is also an important topic in the research field of the roll.In this paper, by changing the laser process parameters defocus on alloys high speed steel roll Fe-2%C-6%Cr-3%Mo-2%W-5%V under heat treatment, mainly use scanning electron microscopy (SEM), energy spectrometer (EDS) and hardness tester to study hardened layer organization, mechanism and hardness of high-speed steel roll material surface after laser heat treatment.The results show that after laser heat treatment, phase transformation hardening zone and heat affected zone hardness of high speed steel roll are improved, the hardened layer was refined. Hardening zone lower than surface hardness, subsurface hardness is highest, and the more near the HAZ at the boundary of the transformation hardening zone, the more coarse and dense secondary carbide, these composite carbides of spherical and strip can effectively prevent the hot cracking expansion during hot rolling, and enhance the wear resistance of the roll. In the experiment, keep laser power and scanning constant,defocusing amount is0, In the transformation hardening zone, part of the high speed steel roll surface of a substrate to produce vaporization melting, auxiliary gas blowing will be formed when the plasma shielding, further hindering its surface absorption of laser energy; And high-speed steel roll surface micro-projections will affect the smoothness of the melting zone roll surface. When the defocus amount is positive10mm, HSS roll surface smoothness and hardness, the hardness of the subsurface maximum847HV, the matrix hardness is2to3times, the hardened-layer depth between0.5mm～0.6mm, is suitable for industrial rolls applications. When the defocus amount is positive20mm, hardness and depth are the lowest in the hardened layer.