热处理工艺对Fe-12Mn-xNi-4C-3.5Si铸铁组织与性能的影响

熔炼出3种不同镍含量的Fe-12Mn-xNi-4C-3.5Si(x=5%,10%,15%)系合金铸铁,研究了不同的热处理工艺对合金组织和性能的影响.结果表明,合金中碳元素的石墨化倾向随着Ni含量增加而增大;经高温退火处理后,合金组织由奥氏体基体、石墨及少量点状碳化物组成;合金中Ni含量越高,碳化物在高温下越容易分解.淬火处理后由于获得了单一奥氏体基体,合金的冲击韧度和抗弯强度均有较大提高,Ni含量越高韧性提高越显著,经900 ℃、8 h保温后淬火的Fe-12Mn-15Ni-4C-3.5Si合金,在三点弯曲试验中可弯成120°不裂,冲击韧度提高至50.2 J·cm~(-2),淬火后由于碳化物被消除,合金的硬度下降,磨损率增大.

Effects of heat treatment on microstructure and properties of Fe-12Mn-xNi-4C-3.5Si cast iron

The effect of different heat-treatment processes on microstructure and properties of Fe-12Mn-xNi-4C-3.5Si cast irons with different nickel content（x=5%，10%，15%）was investigated.The results show that the tendency of graphitization in the alloys increases with increasing of nickel content.After annealing at high temperature，the alloys with austenite matrix，graphite and a few globular carbides can be obtained，and higher nickel content can promote the further decomposition of carbide distributed on the alloy matrix.The impact toughness and tensile strength are obviously improved due to the obtaining of single austenitic matrix after uenching.With increasing of nickel content，the impact toughness increases significantly.The Fe-12Mn-10Ni-15N-4C-3.5Si alloy，heat treated at 900 ℃ for 8 h and quenched，can present 120°V-shape in three-point bending test without brittle fracture，and its mpact toughness substantially increases to 50.2 J·cm~(-2).However，lower hardness and higher wear ratio of alloys result from the decomposition of the carbide after quenching.