Research On The Inhomogeneity Of Explosive Welding Composite Plates Bond Interface

Explosive welding composite plates has the excellent characteristics of each metal components.Compared with a single material,with more excellent performance and cost benefits.So they are widely used in many industry fields such as aerospace,petrochemical,military industry,shipping and nuclear industry,etc.Explosive blast pressure make the metal surface build interatomic bonding force,achieve strong metallurgical bond.The paper mainly study microstructure,explosion welding defects,element diffusion,mechanical property and corrosion resistance by using metallurgical microscope,Scanning electron microscopy,microhardness tester,Nano indentation and Electrochemical corrosion testing methods.The results show that:The interface of composite plate is bonded with the pattern of wave,exists two kinds of combination way: direct combination and melting layer combination,Great plastic deformation occurs in base metal Q345 R side,is divided into fine grain zone,fiber zone,distorted grain zone and original structure.After annealing treatment,the fine grain zone structure occur recrystallization,form fine equiaxed grain.the grains of fiber zone were elongated into streamline shape,Lamellar cementite broken parts occurred spheroidization of cementite.The deformation of distorted grain zone is relatively small.Cladding metal Monel400 is divided into fine grain zone and original structure,surface has the rheological line.Base metal side decarbonizes,a submicron grain zone is at the edge of bonded plate.There are swirls and melted layer in bond interface.the swirl consists of equiaxed fine grains,columnar grains,equiaxed dendrites and cellular grains.The diffusion phenomenon occurs among alloy elements(Fe,Ni,Cu)in bonding interface.the diffusion area of direct combination is narrow,the diffusion area of melting layer combination is relatively wide.Microhardness of explosive welding bond interface is higher than original structure's.The rank of ferritic hardness in different zones is: fiber zone(2.17GPa)>distorted grain zone(2.11GPa)> original structure(1.94GPa);The rank of pearlite hardness is distorted grain zone(2.56GPa)> fiber zone(2.50GPa)> original structure(2.41GPa).The change of elasticity modulus in different zone is same as nano hardness.Microhardness of fine grain zone in cladding metal side is highest.Elasticity modulus and hardness of fine grain zone in cladding metal side is higher than original structure's.Monel400 exhibits passivity.corrosion current is lower and corrosion potential is higher in 3.5%NaCl.The corrosion resistance is excellent.while the corrosion resistance of the explosive welding interface decreases,The corrosion resistance of base metal is worst.