Abstract
The metallurgical structure of martensitic stainless steels changes with temperature transition. It is difficult to get the desired hard structure with fabricating by using conventional manufacturing way in Wire and arc-based additive manufacturing (WAAM). The reason is that WAAM repeats heating and cooling. In this study, We propose a new manufacturing method: thin layers are continuous manufactured at high speed without stopping between passes. Objects were made hotter and had simple temperature history. In addition, we used two different water cooling processes for the new method. As a result, the objects manufactured by conventional methods not only had uneven hardness as in other studies, but also had bad corrosion. In contrast, the objects manufactured by proposed method had uniform hardening and good corrosion resistance comparable to rolled steels. In particular, the hardness of objects cooled by simultaneous water cooling during manufacturing was close to expected max. hardness. However, when water cooling was applied to the proposed method, the tensile strength was low and varied. This is thought that be influenced by hydrogen. SUS420j2 is known as a material that is easily embrittled by hydrogen. It is necessary to pay attention to delayed cracking and to perform low-temperature tempering treatment.
