Improving the welding technology for high-strength steels in their heat-treated condition

To prevent the formation of cold cracks and brittle fracture in the weld zone when welding steels of the 30KhGSN2A type in the heat-treated condition, it is recommended to use austenitic filler material. However, this results in higher strength heterogeneity of the welded joint and the presence of weak zones requires a large increase of the local thickness, thus minimising the gain in weight from using high-strength steel. The improvement of the structure of the weld zone in deposition of edges in two to three layers with low-carbon filler metals does not increase the strength of the joint. To solve this problem, investigations were carried out in this work with the application of filler materials of increased strength, increasing the thickness of the deposit to the width of the heat affected zone (HAZ) followed by strengthening heat treatment after facing the edges. The experiments were carried out on 10 mm plates of 30KhGSN2A and 35KhS2N3M1FA-ID steels. Instead of using Sv-10Kh16N25AM6 austenitic wire, welding was carried out with bainitic and martensitic-austenitic Sv-12Kh2NMA-VI, Sv-15Kh2NMTsRA-VI and Sv-06Kh13N6M4K8B-VI wires with a strength of sigma sub B approx =1000 MPa.