Paper Title
Mechanical Properties and Residual Stress of Dissimilar Material Welding Joints Evaluated by Ball Indentation Technique and Finite Element Modeling

Abstract
One of the extremely interesting research topics is the development of advanced technologies to evaluate the mechanical properties of dissimilar materials welding (DMW). Residual stresses induced by the gas tungstan arc-welding of steel joints in power generation plants are a concern to the industry. In literature many articles are available relating to instrumented ball indentation technique (BIT) by which it is possible to determine few mechanical properties of ductile materials. Majority of them were aimed to determine yield strength (YS), ultimate tensile strength(UTS), work hardening (n), Strength coefficient (K), hardness etc. Only very few of them were addressed to evaluate fracture toughness of ductile materials especially for steel. Further, determination of residual stress (RS) using indentation technique is scanty in literature. With this background, the determination of RS through BIT is a unique effort. Development of an advanced finite element (FE) simulation of BIT experiment using ABAQUS was an important part of this work. The materials used in this study were Low alloy steel and 304 stainless steel. Most of the investigations related to dissimilar metal joints are limited to assessment of microstructure, determination of micro-hardness across weld center and evaluation of bulk tensile properties. In this context, few attempts were made in carrying out residual stress analysis across the fusion boundary using commercial software and fabrication parameters. Microstructure and micro hardness of different regions was examined for the DMW joints. Apart from conventional destructive tests, BIT test was carried out by non-destructively. The obtained mechanical properties by BI techniques, FE simulation revealed satisfactory co-relation with conventional test. This technique proved to be useful in identifying the failure prone area across the welded joint.