Characteristics of strain-induced martensitic transformation in welded joints with the structure of metastable austenite

Abstract

Welded joints of medium-carbon steel were performed by arc welding in shielding gases using cored wire of 50Cr18 type. Phase transitions in the process of crystallization and subsequent thermal and deformation effects under loading were studied. For this purpose, the weldability, wear resistant tests and structure study results were analyzed. It was found that the structure contains an increased amount of metastable austenite, δ-ferrite and high-strength carbonaceous-chromiс martensite. Welded joints have a high capacity for intensive hardening during local deformation due to the TRIP effect. At the same time, they are highly resistant against the formation of cold cracks, which is the main defect in the welds of medium-carbon steels. It was shown that these features are reasoned from the heterophase dissipative structure of the weld metal formed under the conditions of a typical thermal-deformation cycle of the welded joint. © 2019 The Authors. Published by Elsevier B.V.