Delayed fracture of tee-joints of high-strength steels

摘要

The delayed fracture susceptibility and stressed-strained state were studied in tee-joints of high-strength steels made with wires of Sv-O8G2s, Sv-1OKhG2SMA and SvO8KhN2GSMYu grades. The transverse shrinkage of the weld metal of welded joints(Sv-08G2S wire) is shown to cause the metal stretching in the HAZ. Cracks also initiate here. In welding with Sv-O8KhN2GSMYu wire, transformations first occur in the HAZ metal, and then in the weld metal with a noticeable enlargement of the dimensions ofthe crystalline lattice, this leading to compression of the base metal areas adjacent to the weld. This predetermines the formation of cold cracks in the low-ductile weld metal. No essential improvement was found in the delayed fracture resistance ofwelded joints made with Sv-08G25 wire.