Effect of High-Temperature Exposure on Low-Carbon Steel Welded Joint Metal Fracture Toughness

Comparative testing for crack resistance (fracture toughness) of weld metal specimens of a low-carbon steel welded joint in the as-supplied condition and after high-temperature exposure at a temperature of 1200 °C for 3.7 hours is conducted. A welded joint is obtained by automatic argon-arc welding with a consumable electrode in a hot-rolled 22K-type steel sheet of 60 mm thick using welding wire grade SV-08G2S. Tests for static crack resistance of specimens with a stress concentrator are carried out according to a three-point bending scheme. One of the energy criteria of nonlinear fracture mechanics, critical J -integral [J/m 2 ], which takes into account plastic deformation at a crack tip, is used as a crack resistance characteristic. It is shown that high-temperature exposure leads to an increase in crack resistance (the J -integral value increases by two times) as a result of phase recrystallization and improving the coarse-grained overheated weld structure.