Domestic ML45CrMo steel was conducted austempering treatment tests.The specimens were heated and held in a SY805-5 mesh belt furnace,and then placed in a nitrate salt bath for austempering.The mechanical properties and microstructure of the austempered specimens were tested and observed by means of Vickers hardness tester,universal testing machine and metallographic microscope.The results show that after bainitic austempering,i.e.quenching at 850 ℃ for 80 min,austempering in nitrate at temperature of(320±10)℃,holding for 60 min in nitrate,the ML45CrMo steel meets the property requirements of grade 16.8 bolts.
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