Effect of B4C Addition on Microstructure and Mechanical Properties of Powder Metallurgy M3:2 High-Speed Steel
M3:2 high-speed steel(HSS)with B4C addition were manufactured following a conventional powder metallurgy(P/M)route.0.1-0.6 vol.%B4C and pre-alloyed M3: 2 HSS powder were wet mixed and uniaxially compacted at 700 MPa,followed by vacuum sintering to optimize the B4C addition amount.Then the as-sintered samples were heat-treated by spheroidizing annealing,quenching and multiple tempering.The prepared high-speed steels were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)equipped with an energy dispersive X-ray Spectrometer(EDAX),and electron probe micro-analyzer(EPMA).The results reveal that after sintered at as low as 1190℃ the HSS with 0.2 vol.%B4C addition has a relative density of~98.50%and exhibits the best comprehensive mechanical properties,i.e.the Rockwell hardness~53.2±0.2 HRC and the bending strength 3074±56 MPa,which accordingly remarkable increases by~1.9%and~10.5%compared with those of the sintered densification HSS without the addition of B4C.It is speculated that B4C decomposed into boron and carbon during the sintering process,while majority of boron atoms distributed in M6C carbides,with a small amount distributed in the MC carbides and iron matrix and a few of undissolved them formed transient liquid phase during sintering.Meanwhile,the carbon atoms promoted the formation of more MC carbide phase and acted to reduce the solidus temperature of the HSS,which are all conducive to densification and the mechanical property improvement of HSS.After heat treatment,the hardness and the bending strength of the HSS further increase to 61.2±0.3 HRC and 4356±64 MPa,respectively.
Powder Metallurgy High speed steel B4C Heat treatment Mechanical Properties
Li Songlin Zhang Fengli Luo Peng Ouyang Qi He Qinqiu Hu Ming
State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China Institute of Materials for Clean Energy Manufacturing,School of Materials Engineering,Shanghai Dianj
国际会议
北京
英文
1114-1124
2018-09-16（万方平台首次上网日期，不代表论文的发表时间）