STUDIES ON WELDABILITY OF MARTENSITIC STAINLESS STEEL USING THERMO MECHANICAL SIMULATOR

Abstract

The objective of dissertation is to study the influence of welding parameters like energy input, weld speed, heating rate, holding time, cooling rate on microstructure and mechanical properties in the heat affected zone region by simulation. Here steel is subjected to different thermal cycles and/or mechanical deformations. These thermo mechanical cycles may (deliberately or not) alter the mechanical properties of the steel. To have a more in-depth and quantitative understanding of the effects of the thermo-mechanical cycles at a lab scale, Gleeble tests can be performed. The present study deals with heat affected zone (HAZ) simulation of 13/4 martensitic stainless steel using a thermo mechanical simulator, Gleeble® 3800. HAZ simulation helps in identifying suitable welding parameters like heating rate, cooling rate, peak temperature, and energy input to the welding process for a given material for ensuring desirable mechanical properties, tensile strength, ductility and toughness in welded parts. In this work, an assessment of the mechanical properties of weld simulated specimens like Charpy impact toughness, tensile properties and hardness is done. Peak temperatures of 1000°C, 1200°C and 1325°C and preheat temperatures of 30°C and 121°C are used at a constant heating rate of 100°C/s. High impact toughness (52.8 J) and ductility (19.3%) is observed with peak temperature at 1000°C and 121°C preheat temperature. The as-received steel possesses impact toughness of 55.5 J and ductility of 21%, respectively