Microstructure evolution and mechanical properties of two kinds of weathering steel welded joints

The microstructural evolution and mechanical properties of welded joints for Q450NQR1 and Q450AWR5 alloys were investigated. The inhomogeneous microstructures of Q450NQR1 and Q450AWR5 welded joints can result in heterogeneous mechanical responses. Microhardness distributions of the two welded joints are not uniform with the highest hardness value in the FZ, followed by the HAZ, and the lowest hardness value in the BM. The tensile strength of Q450AWR5 welded joints is slightly higher than the Q450NQR1 welded joints. The tensile fracture occurred in the BM of both welded joints, probably due to the strengthening effect of bainite with high dislocation density and lattice distortion. The fatigue life is dominated by the welded defects inside the welded joint. The location of fatigue failure occurs mainly near the fusion zone and is limited by the welded defects, independent of the microstructure.

Automated summary

The microstructural evolution and mechanical properties of welded joints for Q450NQR1 and Q450AWR5 alloys were investigated. The inhomogeneous microstructures of the welded joints can result in heterogeneous mechanical responses. The microhardness distributions are not uniform and the tensile strength slightly differs between the two welded joints. However, the fatigue life is dominated by the welded defects in both cases.