Abstract
Progress in welding with regard to ferritic, austenitic, and duplex-microstructure grade steels is discussed. In transformable ferritic steels, the influence of second-phase particles on welding behaviour is an important theme and examples given include their effect on: (a) heat affected zone (HAZ) microstructure, hardenability, and toughness; (b) HAZ reheat cracking; (c) weld-metal microstructure and toughness; and (d) weld-pool behaviour during arc welding. The improved quantitative understanding of factors controlling solidification and hydrogen-induced cracking in weld deposits is also discussed. In high-alloy austenitic grades, a greater awareness of the advantages of fabricating low-C grades is noted, together with recognition of the important role of residual stress in the development of intergranular stress-corrosion cracking. Factors controlling the creep properties of austenitic weld metal have been clarified, and methods of producing highly aligned columnar grains in multipass austenitic welds have allowed improved ultrasonic inspectability and the prospect of better control of weld-joint properties. Lower interstitial contents have been found to improve the weldability of ferritic stainless grades, and systematic welding studies have led to improved microstructures and properties in weld regions of duplex ferritic-austenitic grades, through modification to the base compositions.
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