Development of Weld Thermal Simulation for Gas Flame Heating

Abstract

Direct experimental methods to investigate changes in micro-structure and mechanical properties in Heat - Affected Zone (HAZ) of weld plate is almost impossible , due to small size of HAZ . The only alternative available is to undergo simulation studies , which can be carried out theoretically as well as experimentally . Experimental simulation can be done with the help of a open and closed loop systems. Closed loop simulation is expensive as compared to open loop simulation . With this in mind , an attempt has been made to carry out simulation studies with the help of an open loop type thermal simulator using gas flame as an inexpensive heating source . In it emphasis is given on peak temperature and at-part of the thermal cycle . These factors are mainly responsible for the phase change of steel. Theoretical simulation is done by considering assumed linear continuous cooling time ( CCT ) curve and a computer programme has been developed for this analysis. Comparison of results for hardness is made for both the techniques . Hardness trend obtained from the computer aided simulation , appears to be closely related to the experimental results , with the variations of cooling rates in the critical zone .