MICROSTRUCTURE IN LASER FUSED HIGH SPEED STEEL W6Mo5Cr4V2(M2)

摘要

Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2（M2）melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM₆C_■ Cr₇C₃ and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV_0.1=865—960 of the laser fused structure of the alloy is due to the oc-currence of martensite.