Analysis on Microstructure and Performance of Plasma Beam Remelt-solidified Layer on Nodular Cast Iron Surface
The microstructure and performance of plasma beam remelt-solidified layer on nodular cast iron surface were analyzed.The results show that the micromelted-solidified hardening of nodular cast iron surface can be realized when working current is 50 A.With the working current increasing,the width and depth of remelt-solidified layer and hardened layer increase,hardness goes down.The graphite phase in remelt-solidified region vanishes after remelt-solidified hardening.The microstructure of remelt-solidified is tiny ledeburite and remaining austenite;and the microstructure in transformation hardening region is acicular martensite,remaining austenite,spheroid graphite and ferrite.The microstructure of double shell around the graphite nodular is advantageous to enhance wear resistance.From the surface to inner,the microhardness shows a tendency of firstly goes down and then goes up,after achieving the top,the value slowly drops.