A review of LTT welding alloys for structural steels: design, application and results

A great deal of effort goes into production of modern steel for structural applications. The structural integrity of the steel becomes compromised when it is welded to form engineering components. The structural capacity of the steel joints is further reduced if the joint is to serve in a fluctuating stress environment. This is because, the fatigue strength (FS) of the steel structure is now shifted to the welded joints. One of the major factors that deteriorate the FS of welded joints is tensile residual stress (TRS). There have been efforts in the last two decades to develop welding alloys capable of mitigating TRS in welded joints based on the phase-transformation of austenite (γ) to martensite (ά). This paper reviews the design, application and results of these alloys often referred to as Low Transformation Temperature (LTT) welding alloys. It also presented the factors affecting them and areas where performance data are lacking.