Microstructural characterization of quenched and partitioned commercial medium carbon steel

Abstract

In order to achieve the desired properties, the microstructure of metals is often modified by heat treatments. A suitable combination of high strength and good ductility can be achieved by adjusting the amounts of martensite and retained austenite through a Quenching and Partitioning (QandP) process. Controlling these material properties offers new potentials in the production of light weight steel parts. This paper presents a basic study of heat treatment conditions with subsequent microstructural characterization of quenched and partitioned commercial 0.54C-1.45Si-0.71Mn spring steel. Beginning from full austenitization, different quenching and partitioning parameters were applied. Microstructural characterization was performed using optical microscopy in combination with different etching methods as well as Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD). It is shown that the intended dual phase microstructure with a specific phase fraction of austenite can be produced. Those results and consideration of hardness measurements show that the investigated commercial spring steel is a promising candidate for improving mechanical properties by a QandP process.