EFFECTS OF WELDING PARAMETERS ON THERMAL CHARACTERISTICS IN WELDED JOINTS OF ULTRA-HIGH HARDNESS ARMOUR STEELS

Abstract

This study examines the influence of welding parameters on the thermal cycle of the welding process—specifically, heat input, cooling time, and average cooling rate—in welded joints of ultra-high-hardness quenched and tempered (UHH-Q&T) armoured steel. Preliminary experiments were conducted to establish fixed parameters for the main tests, including gas flow rate, welding voltage, wire diameter, and wire feed speed, based on the technological capabilities of the welding equipment. The primary experiments utilized the conventional gas metal arc welding (GMAW) process, in which welding speed and stick-out were varied according to a full factorial design, while the current remained constant. The key thermal cycle variables of the welded joints were determined using theoretical heat flux equations, validated through dilatometry test simulations. These simulations were further assessed by comparing the microstructural characterization and microhardness mapping of real and simulated heat-affected zone (HAZ) subzones.12