B. Mahato

Effect of Structural Heterogeneity on In Situ Deformation of Dissimilar Weld Between Ferritic and Austenitic Steel

Abstract Low-alloy steel and 304LN austenitic stainless steel were welded using two types of buttering material, namely 309L stainless steel and IN 182. Weld metals were 308L stainless steel and IN 182, respectively, for two different joints. Cross-sectional microstructure of welded assemblies was investigated. Microhardness profile was determined perpendicular to fusion boundary. In situ tensile test was performed in scanning electron microscope keeping low-alloy steel-buttering material interface at the center of gage length. Adjacent to fusion boundary, low-alloy steel exhibited carbon-depleted region and coarsening of matrix grains. Between coarse grain and base material structure, low-alloy steel contained fine grain ferrite-pearlite aggregate. Adjacent to fusion boundary, buttering material consisted of Type-I and Type-II boundaries. Within buttering material close to fusion boundary, thin cluster of martensite was formed. Fusion boundary between buttering material-weld metal and weld metal-304LN stainless steel revealed unmixed zone. All joints failed within buttering material during in situ tensile testing. The fracture location was different for various joints with respect to fusion boundary, depending on variation in local microstructure. Highest bond strength with adequate ductility was obtained for the joint produced with 309L stainless steel-buttering material. High strength of this weld might be attributed to better extent of solid solution strengthening by alloying elements, diffused from low-alloy steel to buttering material.

Evolution of Recrystallization Texture in AISI300 Series Austenitic Stainless Steels After Cold Rolling to Large Strain

The present paper deals with the evolution of texture in austenitic stainless steels during annealing after 95% cold rolling. After 95% cold rolling, the texture is mainly of the brass type {110} along with a scatter towards the S orientation {123} and Goss orientation {011} . Weak evidence of Cu component is observed at this high deformation level. During annealing, recovery is observed before any detectable recrystallization. After recrystallization, the overall texture intensity was weak; however, there are some discernible texture components. There was no existence of the brass component at this stage. Major components are centered on Goss orientation and Cu component {112} as well as the BR component {236} . Also, there are some few orientations which come up after recrystallization i.e. {142} and {012} . With increase in annealing temperature the textural evolution shows emergence of weak texture with another new component i.e. {197} . The evolution of texture was correlated with the deformation texture through twin chain reaction.

Evolution of grain-boundary character distribution during iterative processing of an austenitic stainless steel

The present article deals with the analysis of grain-boundary character distribution (GBCD) and microstructural characteristics after iterative processing of austenitic stainless steel, AISI 316L. The steel was subjected to iterative cold reduction and subsequent annealings. After an initial decrease in the fraction of Σ3 boundaries, the number of these increases in subsequent steps. The results relate the importance of iterative processing and the mechanism of obtaining a higher fraction of Σ3 boundaries.