Bond Interface Inhomogeneity Of 304/Q245R Explosive Welding Composite Plates

304/Q245 R composite plate has been widely used in engineering practice for its corrosion resistance,wear resistance,heat resistance of clad plate and high strength of base plate and other properties.the usage of composite plate is strictly limited by bond interface inhomogeneity under strict service conditions,So it is very necessary to study on structure and properties of bond interface explosive composite plate.Aimed at 304/Q245 R composite plate bonding interface by explosive welding,the study on structure and nano-hardness evolution of pearlite,ferrite and austenite,distribution of element,composition of defects,mechanical properties and corrosion resistance was researched by using metallurgical microscope,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),nano indentation,electrochemical corrosion testing,superfine load hardness tester,Mechanical universal testing machine and other methods.The results are as follows: the bonding interface of explosive composite plate is wave-shaped with about 295?m length and 871?m width of periodic wave.inhomogeneity 500?m width affected zone in composite plate welding area is bonding interface.The classcal bonding interface from base plate to clad plate is composed of base metal side fine grain zone(nanohardness is 2.46 GPa),fiber zone(nanohardness of ferrite is 2.53 GPa and that of pearlite is 4.2 GPa),torsion grain zone(nanohardness of ferrite is 3.02 GPa and that of pearlite is 4.51 GPa),clad metal side white-brighter layer zone(nanohardness is 7.49 GPa),fiber zone(nanohardness is 6.46 GPa)and deformation zone(nanohardness is 6.21 GPa)respectively.Compared with base plate(nanohardness of ferrite is 2.40 GPa and that of pearlite is 3.60 GPa)and clad plate(nanohardness is 5.69 GPa),it has increased differently.The vortex appear in wave-shaped bonding interface of explosive welding.The interior vortex has cracks and pores inclusion.The nanohardness of vortex interior(nanohardness of front vortex is 2.46 GPa and that of back vortex is 6.98 GPa)is nonuniform and different significantly compared with that of base plate and clad plate.Adiabatic shear band appear in shroud plate side of bonding interface which is composed of equiaxed grain from dynamic recrystallization and crystal boundary.The interior hardness 4 GPa of shear band is declined immensely than that of around organization.Compared with original material,the vickers hardness in bonding inerface of explosive composite plate occur work hardening.Contrast with combination layer of explosive composite plate,base plate layer and clad plate layer,the hardening phenomenon from explosive welding shock wave enhance tensile strength and reduce breaking tenacity.The tensile fractures of combination layer of composite plate show up stratified structure.The base plate and clad plate respectively show up different ductile microvoid morphologies in no vortex junction.However,planar crystal and columnar crystal quasi cleavage fracture morphologies are observed in vortex junction,which is the origin resulting to rupture of combination layer of composite plate.Composite plate has good shear property.Shear fracture mainly appear in diffusion layer of Q245 R base plate with quasi dissociation-formed appearance of fracture.The corrosion resistance of bonding interface of composite plate is significantly lower than that of 304 shroud plate under 3.5% NaCl aqueous solution by Electrochemical testing,which is similar with base plate side.There is not obvious galvanic corrosion in wave-shaped interface while evident corrosive pitting in bae plate side under 3.5% NaCl aqueous solution by immersion testing.