Effect of solution temperature on microstructure and mechanical properties of wire arc additive manufactured maraging steel

Abstract

Solution and aging heat treatment (SAT) is an effective method for enhancing the mechanical properties of maraging steel. The solution temperature is a key factor affecting the SAT; however, there is a lack of research on the effect of solution temperature on the organizational properties of wire arc additive manufacturing (WAAM) maraging steel. In this study, thin-walled structures of maraging steel were prepared using WAAM. The microstructures and mechanical properties of the As-deposited (AD) and SAT specimens subjected to varying solution temperatures were systematically analyzed and compared. The AD specimen exhibited obvious segregation behavior of Ti, Mo, and other alloying elements and an anisotropic microstructure and mechanical properties. Following the SAT, the strength of the maraging steel significantly increases due to the generation of nano-precipitated phase. The ultimate tensile strength (UTS) of the AD specimen is 1282.5 MPa, and that of the 900 °C SAT specimen is 1530.8 MPa. At higher solution temperatures, the element distribution is more homogeneous, and the nano-precipitated phases are finer, resulting in a higher strength. The UTS of the 1000 °C SAT specimen increases to 1732.7 MPa. However, at a solution temperature of 1100 °C, the UTS decreases to 1634.1 MPa because of the increase in the grain size and prior austenite grain size. It has been shown that a reasonable solution temperature can attenuate elemental segregation precipitation and promote the generation of a nano-precipitation phase to enhance the performance of the maraging steel without excessively coarsening the grain.