Failure resistance in static loading of steels with ?0.2 > 600 MPa and their welded joints

Abstract

Investigations were carried out into the failure resistance in the temperature range +20 to −60°C in static bending of 13KhGMRB, 14KhG2SAFD, and 14KhGN2MDAFB steels with σ0.2=600–700 MPa and also the weld metal and the heat affected zone (HAZ) of their welded joints. Evaluation of the cracking resistance of these steels and welded joints was carried out using fracture mechanics criteria: critical crack opening displacement δc and stress intensity factor Kc. The values of the effective factor of stress concentration, generated by the crack {ie746-01}, and critical stress σcr are also determined. The results show that of the three steels tested, the lowest failure resistance was exhibited by 14KhGN2MDAFB steel. The heat affected zones of the welded joints in the 13KhGMRB and 14KhGM2MDAFB steels have higher cracking resistance than the HAZ of the welded joints in 14KhG2SADF steel. The weld metal of welded joints produced in CO2 with PP-AN54 wire and in a Ar+CO2 mixture with Sv-08KhN2GNYu wire is characterized by higher failure resistance than the weld metal of welded joints produced in CO2 with Sv-10KhG2SMA wire. The welded joints in 13KhGMRB steel produced in CO2 with PP-AN54 wire, and in 14KhGN2MDAFB steel produced in the Ar+CO2 mixture, have high failure resistance at temperatures to −60 and −50°C, respectively. The welded joints in 14KhG2SAFD steel, produced in CO2 with Sv-10KhGSMA wire, can be used in service at temperatures not lower than −40°C.