Evaluation of Zero and Sub-zero Temperature Tensile and Impact Properties of Quenched and Tempered Steel Weldments

Combat vehicles using armour grade quenched and tempered (Q&T) steel are needed to be operated under different climatic conditions. However, the properties meeting the room temperature test conditions may not necessarily be required to meet the low temperature operating conditions. The influences of shielded metal arc welding (SMAW) process, flux cored arc welding (FCAW) processes and test temperatures below room temperature up to-60 °C on tensile and impact toughness properties of armour grade Q&T steel welds were reported. The tensile and impact properties of the joints showed incremental trend with respect to the decrement in test temperature up to −40 °C irrespective of the welding processes used. The increment in tensile and impact properties of SMAW and FCAW joints subjected to the low temperature environment is due to plastic strain-induced phase transformation of retained austenite into martensite phase. Among the two processes, SMAW process welded joint showed better tensile and impact properties than its FCAW counterpart joints.