Effect of beam wobbling on microstructure and hardness during laser welding of X70 pipeline steel

Abstract

Laser welding with beam wobbling was employed to weld X70 pipeline steel. The influence of beam wobbling on weld surface morphology, fusion zone microstructure, and microhardness was investigated. The formation of spatter was suppressed by beam wobbling using a beam with higher energy density. At a welding speed of 1.0 m min −1 , the weld metal produced with a circular laser wobble pattern contained more martensite but less ferrite, compared to that of static spot welded joint. The presence of more martensite led to the increase in fusion zone hardness. A softened region was found in the inter-critical heat-affected zone. The hardness of the softened region could be improved by increasing the welding speed (from 1.0 to 1.5 m min −1 ).

Effect of Wire Preheat and Feed Rate in X80 Steel Laser Root Welds: Part 2 — Mechanical Properties

“…2-4), and a high cooling rate which could result in the weld metal brittleness (Refs. 1,5). In recent years, novel technologies like hybrid laser arc welding (HLAW) (Refs.…”

“…Morden pipelines are made of high-strength low alloy (HSLA) steels due to their high strength and superior toughness (Ref. 1). Welding is an essential process for fabricating large-scale pipelines, which determines the productivity and reliability of the pipeline system.…”