Influence of cryogenic treatment on mechanical and ballistic properties of AA5754 alloy friction stir welded joints  

作　　者：V.Manoj Mohan Prasath S.Dharani Kumar Saurabh S.Kumar 

机构地区：[1]Department of Mechanical Engineering,KPR Institute of Engineering and Technology,Coimbatore 641407,India [2]Scientific Officer,Ballistic Research Centre&Testing Range,National Forensic Sciences University,Gandhi Nagar 382007,India

出　　处：《Defence Technology(防务技术)》2025年第4期184-198,共15页Defence Technology

摘　　要：In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-piercing(AP)bullet at an impact velocity of 682±20 m/s.The FSW technique was used to prepare the welded samples for AA5754,with an axial force of 7 kN,a feed rate of 20 mm/min,and a speed of 1200 rpm.The cryogenic treatments performed after welding,including deep cryogenic treatment(DCT)at196C and shallow cryogenic treatment(SCT)at80℃,for 6 and 72 h,respectively.The microstructure and mechanical characteristics of cryogenically treated and untreated joints were examined.The cryogenic treatment refined the grain size(1.05 mm)and enhanced the microhardness(93 Hv).Moreover,DCT-FSW significantly improved the tensile strength(13.93%)and impact strength(8.45%)compared to untreated FSW sample.Additionally,in untreated FSW samples,the fracture behaviour varied:the impact fracture mode primarily exhibited ductile failure,while the tensile fracture exhibited a mixed fracture mode.In contrast,the tensile and impact fracture modes of the DCT-FSWwere dominated by a ductile failure mode.The DCT-FSW target demonstrated a lower depth of penetration(DOP)of 31 mm compared to the SCT-FSWand untreated FSW targets.Post-ballistic SEM analysis in the crater region of all three zones revealed the formation of frictional grooves,small cracks,and adiabatic shear bands(ASBs).

关 键 词：AA5754 alloy Ballistic and mechanical properties Cryogenic treatment Depth of penetration 

分 类 号：TG457.1[金属学及工艺—焊接]