Microstructure and properties of A508-3 steel welded joint based on tempered bead technology

Ni-based alloy electrode Ni690 was deposited on the surface of A508-3 steel with tempered bead technology for dissimilar materials, the microstructure and properties of the welded joint with temper bead was analyzed and compared with welded joint under conventional welding technology +590^\circ \mathrmC \times 2 \mathrm~h post weld heat treatment (PWHT). The result showed that the hardness of coarse-grained zone of welded joint under conventional welding technology + PWHT decreased obviously, but the hardness of martensite zone did not decrease obviously. The hardness of coarse-grained zone and martensite zone of welded joints with tempered bead technology was obviously reduced. The tempered bead technology could soften coarse-grained zone and fusion zone. Although the hardness of the coarse-grained zone was about 73 \% \sim 89 \% that under heat treatment, the uniformity of joint hardness was better. From the test results, an ideal welding method for repair welding or manufacturing of large structures and avoiding PWHT was tempered bead technology.