The Optimization Of Preparation Process Parameters Of Spray Forming Large Diameter High-speed Steel

The large diameter high speed steel is mainly used for manufacturing large broach，gear hob, slotting cutter, multi-roll cold rolling mill roller and high quality die. Carbide isthe basic guarantee for HSS performance. The microstructure has influence on toolperformance, especially on toughness and life. Due to the limitation of technology andequipment, a large section of high-speed steel domestic production, qualified rate is lowand the presence of coarse carbide particles is not uniform, has become a technicalproblem of high speed steel industry development of China’s tool industry.using rapid solidification method. The carbide of HSS billet produced by spayforming is fine and evenly distributed and it can solve key technical issues of largediameter HSS billet with low pass rate of carbide distribution and large sizedcarbide.However, the research of producing large section HSS billet using spay forming isstill blank in the domestic.Based on the above, the preparation of HYM35and HYM2E billet was studiedexperimentally using HEYE Special Steel Co.,LTD. spray forming equipment and HebeiUniversity of Science and Technology experimental conditions. The effect of molten steeltemperature, atomization pressure,molten steel flow and other parameters on carbidedistribution, carbide size and carbide size distribution has been studied. Themicrostructure and properties of HSS prepared by spray forming and ESR has been testedand analyzed. Based on testing results, the major conclusions are as follows.1、During the preparation of HYM35and HYM2E by spray forming, the increase ofmolten steel temperature and atomization pressure can improve carbide distribution.However, the high molten steel temperature can make carbide size increase.2、The solidification microstructure of HYM35and HYM2E is equiaxed grain withuniform size and fine carbide network precipitated along the grain boundary. Thethickness of carbide network is significantly smaller compared with ingot castmicrostructure of ESR HSS.3、The carbide distribution of HYM35and HYM2E HSS forging bar by sprayforming is improved obviously compared with ESR HSS forging bar4, Compared with ESR HSS forging bar, the bending strength and impact toughnessof HSS forging bar by spay forming has been improved after same heat treatment and thelongitudinal impact toughness of HYM35increased by61%.