Journal of Material Sciences & Engineering

Experimental Determination of Cooling Rate and its Effect on Microhardness in Submerged Arc Welding of Mild Steel Plate (Grade c-25 as per IS 1570)

Abstract

Rahul Kumar, Harish K Arya and Saxena RK

An experiment based thermal analysis has been performed to obtain the thermal histories, which can be applied to determine cooling rate of weldment. During fusion welding process it is possible to determine temperature at any point by using thermocouple and from such data it is possible to draw thermal histories for any point of interest, such thermal histories can be utilized to determine cooling rate. The temperature distribution and cooling rate during the welding process have significant effect on the mechanical and metallurgical properties of a weldment. The changes in microstructure, grain growth and hardness in a weldment are very dependent on the temperature distribution and cooling rate. These studies are utilized to investigate the micro-structure and microhardness of the heat affected zone (HAZ) and weldment. In present work, the influence of heat input and cooling rate on microhardness has been investigated. Full factorial design is used to conduct the experiment with three factors and two levels. Eight combinations and two set of heat input are designed with different combinations of SAW welding parameters. Temperature distribution curves and cooling rate have been drawn. The effect of selected welding parameters (Wire feed rate, Open circuit Voltage and welding Speed) on the microhardness have been investigated.