Inhomogeneity And Electrochemical Properties Of Explosive Welding Bonding Interface

Due to its comprehensive performance of corrosion resistance and strength,explosive clad plate showed widely prospects in the preparation of large area and special composite materials,and had been widely applied in pressure vessels and transportation fields.However,the inhomogeneity of the composite plate at the interface severely restricted its development advantage.In this paper,the 304/Q245 R and TA2/316 L composite plates were tested for metallographic,electrochemical,hardness,tensile and shear tests.The conventional and low temperature impact tests for TA2/316 L and 316L/15 Cr MoR composite panels were carried out.By means of metallographic microscope,nano indentation instrument,mechanical universal experimental machine and so on.The level of the interface,structure,mechanical properties and the law of electrochemical performance and its formation mechanism were studied systematically.The main research results were as follows.The bonding interface of the explosive composite plate had the characteristics of different levels,different degrees of deformation and significant changes in the structure of the tissue.The width of the bonding interface was about 500 m~800 mu m,which run through the five layers of the cladding plate and the substrate.For example,the microstructure of the carbon steel side of the composite plate was the fine grain region,the fiber area and the torsional zone in turn and The stainless steel side was divided into the fiber area and the deformation zone in turn.Whirlpool defects and adiabatic shear lines existed at the interface.Due to the gradually weakening of the deformation degree of the two sides of the cladding plate,the hardness of the cladding plate gradually decreased with the extension of the substrate to the cladding plate.The bonding interface of the 304/Q245 R composite plate existed the front vortex(3.14GPa),the post vortex(7.01GPa)and the adiabatic shear line(7.45GPa).The hardness of fiber zone in the side of carbon steel was the highest(ferrite 3.84 GPa,pearlite 4.74GPa).In the hierarchical tensile test,the interface strength was higher(617MPa)but its toughness was poor,elongation(8.31%)only for the cover plate 30.3%.The strength and plasticity of the side of the substrate gradually increased with the distance from the bonding interface.The shear strength of the composite plate was good,and it was ductile fracture and the fracture position was in the wavy interface.There were high hardness adiabatic shear lines(7.16GPa)and vortices(14.33GPa)at the stainless steel side interface of TA2/316 L composite plate.The shear fracture was brittle fracture at the side of the bonding interface near the trough.In the impact test,the average impact energy of the cladding gap and the substrate gap was 410 J and 285 J,respectively,which was up to 30.5%.In the low temperature impact test,the impact work of the cladding side gap is at-50?,and the impact energy at-25? is reduced by 17.7%.In the low temperature impact test,the impact work of cladding plate notch at-50? relative to that of the-25? decreased by 17.7%.The impact work of the substrate side notch at-50? decreased by 25% compared with-25?.In the impact test of 316L/15 CrMoR composite plate,the average impact power(138J)of the composite plate nortch on the side of the cladding plate decreased by 15.1% compared with the side of the substrate.In the low temperature impact test,the impact work of the substrate side notch at-30? decreased by 2.20% and 3.40%,respectively,compared with the impact work at 0? and room temperature.When the impact work of the cover plate notch side at-30?,compared with the impact work at 0? and room temperature decreased by 1.82% and 2.17%,respectively.Due to the hindrance of the interface to the impact,the specimen did not break completely and the wave interface was mechanically exposed.There were fine crystal zone,fiber zone and whirlpool structure in the interface of mechanical peeling.The whirlpool was composed of the micro dendrite and the cellular dendrites in the side and the heart.The electrochemical experiments of the 304/Q245 R and TA2/316 L explosive composite plate showed that the corrosion resistance of the composite plate was the composite plate > the bonding interface > the substrate.The microarea SKP test of 304/Q245 R showed that the corrosion resistance in the interface is fine grain area > fiber area > torsion zone.Grain size refinement within the interface led to an increase in grain boundary ratio and the enhancement of atomic mutual diffusion made the surface easier to form passivating film were the main reasons that the corrosion resistance of the substrate was significantly improved with the interface.