Reseach On Interface Effect And Bonding Mechanism Of Explosively Clad Plate With Groove Interface

Explosive welding employs explosive energy to make metal surface produce intense plastic deformation and to achieve metallurgical bonding between metal plates. Explosive welding is widely used in the manufacture of bimetallic clad plate, and researchers have successfully achieved such welding of hundreds of homogeneous or heterogeneous metallic materials. However, larger welding charge would cause environmental pollution, vibration and noise. Two metal plates would not be bonded with smaller welding energy. However, Superfusion phenomenon was produced with bigger welding energy, which would lead to lower bonding strength at the interface. Concerning numerous questions existing in the explosive welding, honeycomb structure explosive was used as welding explosive. The research ideas on metal plate with groove style interfaces bonded by explosive welding and explosive pressure welding-rolling were proposed.As detonation velocity was known as one of key parameters of explosive welding, to develop a composite explosive dedicatedly used in the metallic plate with groove style interfaces, the influence of size and content of glass micro-balloon particles on the density and detonation velocity of emulsion explosive were studied. The result indicated that explosive density and detonation velocity decreased along with the increase in content of glass micro-balloon particles. The sensitization efficiency and detonation velocity adjustment effect of small-sized glass micro-balloon particles were better than that of big-sized glass micro-balloon particles. Because of uneven density and bigger critical diameter of traditional welding explosive, honeycomb panel was used as the framework of explosive, which, thanks to the constraint of die honeycomb holes in all directions, could not only reduce critical thickness of explosive, but also ensure the same thickness of explosive in different positions and boost the detonation velocity.Due to the bonding interface of aluminum alloy to steel, especially Mg-Al alloy to steel, could easily cause superfusion phenomenon and multiple brittle intermetallic compounds, it is difficult to achieve direct explosive welding of aluminum alloy to steel. So a thin aluminum or titanium steel plate as intermediate plate inserted between them is adopted to achieve explosive welding of aluminum alloy to steel. In order to achieve direct explosive welding of Mg-Al alloy to steel and enhance bonding strength at the interface, a 5083 aluminum alloy plate and a Q345 steel plate with dovetail style interfaces were employed as the flyer and base plates, respectively. The parameters adopted in the explosive welding experiment were close to the lower limit of weldable window of 5083 aluminum alloy to Q345 steel. The bonding properties of 5083/Q345 clad plate were studied through mechanical performance tests and microstrucrure observations. The results suggested that the aluminum alloy plate and steel plate with groove style interfaces were welded under the action of metallurgical bonding, and the meshing of dovetail grooves. It was a new method for the explosive welding of metallic materials with larger difference on the strength. The bonding area of aluminum alloy to steel with groove style interfaces was 145 percent higher than that of the traditional Al/Fe clad plate. Tensile shear strengths of 5083/Q345 clad plate were higher than 172MPa, which met the requirements of bonding strength of Al/Fe clad plate. The microhardness of Q345 steel and 5083 aluminum alloy near the interfae of 5083/Q345 clad plate decreased as the distance from the bonding interfaces increased. The microhardness of Q345 steel and 5083 aluminum alloy at a certain distance from the lower surface of dovetail grooves were basically equal to that of Q345 steel and 5083 aluminum alloy at the same distance from the upper surface of dovetail grooves, respectively. The interfaces between aluminum alloy and the upper and lower surfaces of steel plate with dovetail grooves were mainly welded through direct bonding, and discontinuous molten zone in the local region emerged:while the interface between aluminum alloy and the inclined surface of steel with groove style interfaces was bonded by continuous melted layer. The grains in the Q345 steel region adjacent to the interfaces were elongated. However, no elongated fibrous was observed in the 5083 aluminum alloy region adjacent to the interfaces. The brittle intermetallic compounds FeAl2 and Al5Fe2 were generated at the bonding interfaces of 5083/Q345 clad plate. The fracture surface of the tensile specimen mainly exhibited ductile fracture, and quasi-cleavage fracture exited in the localized region.When the explosive welding of aluminum to steel was conducted by the parameters in the explosive welding window, the inner surface of metallic plate would be prone to get excessively melted, and the bonding properties at the interface of clad plate would be impacted. However, when the welding energy gets lower than the lower limit of weld-ability window, plastic deformation of the metal at the interfaces was lesser, and thus the bonding strength of clad plate would get lower, which might even lead to welding failure. Due to the mechanism of explosive welding of different aluminum alloy to steel of groove style interfaces was the same, a 1060 aluminum plate and a Q345 steel plate with groove style interfaces were respectively used as flyer and base plates. The selected welding parameters were lower than the lower limit of 1060/Q345 clad plate, and plastic flow and metal jet arisen on the side of aluminum alloy only. The effect of metal plate with groove style interfaces on the explosive welding window of 1060/Q345 clad plate was researched. The results showed that the clad plate of aluminum to steel with groove style interfaces was bonded tightly with good welding quality. Metallic plate with groove style interfaces could reduce the lower limit of explosive welding window of aluminum to steel. Aluminum and the upper surface of steel with dovetail grooves were bonded in a linear shape combined with a wavy shape. However, the aluminum bonded with the lower and inclined surfaces of steel with groove style interfaces exhibited a wavy shape. No inter-metallic compounds existed at the interfaces.Traditional explosive welding energy of titanium to steel was larger. Bonding rate was lower with thicker titanium layer, and even welding failing existed at the interface. Concerning numerous questions existing in the explosive welding of titanium to steel, laminar clad plates bonded by explosive pressure welding-rolling of loose-fit dovetail-groove metal plate were proposed. TA2 titanium with dovetail grooves and Q345 steel plates with dovetail grooves were selected respectively as flyer and base plates. Honeycomb structure explosive was used as the source of energy for explosive pressure welding to research the explosion pressure welding-rolling bonding of titanium to steel. The bonding property of titanium-steel clad plate was analyzed through mechanical property testing and microstructure morphological observation. And then, by means of heat treatment, the effect of annealing temperature and time on the microstructure at the interfaces of titanium-steel clad plate were studied. The results showed that the metallurgical bonding at the interfaces of loose-fit TA2 titanium and Q345 steel plates was achieved by explosive pressure welding-hot rolling through meshing of dovetail grooves and mutual diffusion between the two metals. After the explosive pressure welding, metallurgical bonding failed at the interfaces of titanium-steel clad plate, and gap with a width of 5mm to 45mm appeared at the interfaces. And after the explosive pressure welding-rolling, the interfaces of clad plate were basically welded by direct bonding. No inter-metallic compounds were generated at the interfaces of titanium-steel clad plate, and the grains on the side of steel layer exhibited fibrous shape. Heat treatment could eliminate deformed microstructure on the side of steel of clad plate. The thickness of transition layer increased along with the increment in annealing temperature and time. When annealing temperature and time were respectively 700℃ and 0.5h, perfect bonding quality was achieved at the interfaces of titanium-steel clad plate bonded by explosive pressure welding-hot rolling.