Effect of controlled rolling and cooling on the microstructure and mechanical properties of 60Si2MnA spring steel rod

Abstract

The effect of controlled rolling and cooling process parameters, such as finish rolling temperature, loop-laying temperature and the cooling rate in the process from the loop layer to the coil station, on the microstructures and mechanical properties of 60Si2MnA spring steel rod were carefully investigated by thermal simulation, tensile tests and quantitative metallography. Experimental results indicate that the microstructure is mainly determined by finish rolling temperature, especially the cooling rate in the process from the loop layer to the coil station. In a given range, the more rapid the cooling rate, the thinner the interlamellar pearlite spacing, the less the proeutectoid ferrite bulk volume and the smaller the average ferritic grain size. Low finish rolling temperature is in favor of decreasing pearlite colony size. Therefore, low finish rolling temperature followed by properly accelerated cooling is suggested so as to improve its cold workability.