Effect of Heat-Treated Microstructure on the Polishing Performance for 3Cr17NiMo Plastic Die Steel

Structure features of 3Cr17NiMo plastic die steel quenched at 1030°C and tempered at different temperatures have been analyzed by means of optical microscope, transmission election microscope (TEM), X-ray, electron probing analysis (EPA) and microhardness instrument. Semiquantitative analysis on polishing performance was done using interference microscope in order to determine factor influencing the polishing performance for 3Cr17NiMo plastic die steel. The results show that there existed block ferrite and non-solution granular carbides in metallographic structure for 3Cr17NiMo quenched at high temperature. It is one of main reasons resulting in poor polishing performance for 3Cr17NiMo plastic die steel. Previous analysis is agreed with predicted result using Thermo-Calc software. In order to improve polishing performance for 3Cr17NiMo, Thermo-Calc software was applied to thermodynamic. Simulated results show that the polishing performance can be improved by modifying the chemical constitution of 3Cr17NiMo by reducing the content of C and Cr, and adding N properly.