Investigation of DMW Joints Using Buttering Deposits Prepared with Paste Technique

Authors:

Dinesh Rathod (Manav Rachna International University, Faridabad)

Keywords: Paste technique, Dissimilar Metal Joint, Buttering, Carbon migration, welding.

Abstract:

The main objective of present work was to study the micro-structural changes due to buttering deposit on AISI 1020 steel for dissimilar metal joint of AISI 1020 steel to SS 304 steel. Dissimilar metal joints are extensively used in many industrial applications but due to weldability related issues, they cannot perform satisfactory life. The difference in chemical composition, coefficient of thermal expansion and mechanical properties affects the weldability of the joint. For maintaining elemental compatibility, buttering technique is often used for such joint. It is quite difficult to select the consumables for the buttering layers, which will satisfy the requirement of desirable chemical composition. Carbon migration is one of the major causes for buttering layer deposits. Nickel act as a barrier for carbon migration, so paste technique was used to deposit the buttering layer. The paste was prepared with Nickel powder, ferro-vanadium and ferro-titanium powders and deposited using Tungsten Inert Gas (TIG) welding and Shielded Metal Arc (SMAW) welding. Subsequent layer deposit was made using SMAW using Inconel 182 consumables. Weld joint was prepared between said base metals using SMAW process and Metal Inert Gas (MIG) welding. Micro-structural analysis and micro-hardness analysis were carried out. Nickel rich paste layer deposited using TIG observed micro-cracks or solidification cracks. When deposited with SMAW, due to dilution effect, nickel composition reduced and ferrite content changes in buttering layer hence no any cracks observed. Nickel paste with controlled parameters with direct deposit using SMAW can be successfully applied for such dissimilar metal joints.

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