Studies on the ballistic behaviour of Friction stir welded and post weld Treated az31b magnesium alloy Targets

Abstract

In recent years, lightweight materials replace armor grade steels. newlineAluminium alloys are extensively used in the military tanks and combat newlinevehicles to achieve better transportability and fuel efficiency. Magnesium newline(Mg) alloy (AZ31B) replaces existing high-density materials in a few vehicle newlinearmor applications due to its low density, high damping ability, high specific newlinestrength and better ballistic behaviour. Most of the vehicle armor structures newlineare fabricated by Friction Stir Welding (FSW) process because of its better newlinestructural integrity and ballistic behaviour. Researchers proved that FSW newlinecould yield sound weld joints of AZ31B Mg alloy. Though the FSW is a newlinesuitable process for joining the AZ31B, the selection of process parameters is newlineessential to achieve defect-free FSW joints. The heat generation and material newlineflow behaviour are the important factor that decides quality of the AZ31B newlineFSW joints. newlineIn this thesis, FSW process parameters such as tool rotational (1000- newline1200 rpm) and welding speeds (40-60 mm/min) to produce the defect-free newlineweld joint were identified. Around nine FSW joints were welded within the newlineselected range of process parameters. Based on the mechanical properties, it newlinewas noticed that the tool rotational speed of 1200 rpm and welding speed of newline50 mm/min exhibited better tensile strength and impact energy compared to newlineother joints. In continuation of the research, the predetermined FSW process newlineparameters were used to weld AZ31B plates. The refined grains were newlineobserved at the Stir Zone (SZ) region compared to the Heat-Affected Zone newline(HAZ) and Base Metal (BM). The minimum microhardness was obtained in newlinethe HAZ region compared to other regions. The drop in tensile strength along newlinethe HAZ region of the FSW joints was due to uneven microhardness newlinedistribution and occurrence of tensile fracture newline