The Effect of Quenching and Partitioning (Q&P) Process on the Structural and Mechanical Properties of AISI 4130 Steel

Abstract

In this study, the effect of quenching and partitioning (Q&P) heat treatment on the structural and mechanical properties of AISI 4130 steel was investigated. The Q&P process was followed at a quench temperature of 270 oC and three different partitioning temperatures of 270, 330, and 380 oC. The phase and structural characterization of the prepared spicimens were done using X-ray diffractometer (XRD) and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were also monitored by hardness and tensile test according to ASTM E8 standard. The results showed that the tensile strength can be increased up to 1450 MPa while maintaining the elongation percentage (about 9.6%) by performing the Q&P process on the AISI 4130 steel. This strength is about 20% greater than that of obtained by the usual quench and tempering process in this steel. Optimum partitioning temperature and time for AISI 4130 steel were determined to be 330 °C and 120 minutes, respectivly. Partitioning at lower temperatures could not stabilize the austenite phase, while partitioning at higher temperatures caused the decomposition of the austenite phase and carbide precipitation.