The middle layer of tungsten nickel-iron alloy was prepared by diffusion welding with high strength steel
Tungsten-nickel-iron alloy has been widely used in advanced weapon manufacturing, nuclear industry, aerospace and other fields due to its advantages of high melting point, high strength, high density and radiation resistance. However, due to the poor room temperature toughness of WNiFe alloy, the further expansion of its application is greatly limited. In view of the current situation, the researchers proposed the diffusion welding of WNNI and HSS, which combined the advantages of HSS with high strength and toughness and the advantages of WNNI and HSS with high strength and high density to obtain structural components that meet the service performance.
In order to ensure the service performance of components and realize the high-strength welding of WNiFe alloy and high-strength steel, it is necessary to solve the large difference in the linear expansion coefficient between WNiFe alloy and high-strength steel (A WNiFe alloy = 5-6 ×10-6/K, a high-strength steel = 12-15 ×10-6/K). After welding, there are two key problems: high welding thermal stress and strong reaction tendency of Fe element in high strength steel and W element in WNiFe alloy, and it is easy to form Fe-W brittle intermetallic compounds at the interface.
In view of the current situation, the diffusion welding of tungsten nickel-iron alloy and high strength steel at home and abroad is done by adding intermediate layer. , however, the introduction of the existing middle tier while avoiding the Fe-W is the emergence of intermetallic compound, but by adding the middle layer caused by other intermetallic compounds (such as Nickel, Copper-Tungsten compounds Titanium compound) appear still weakened the tungsten nickel and iron and the strength of the identity of diffusion welding joint, and it is difficult to achieve good release joint welding thermal stress of the goal; In addition, the existing interlayer is mostly introduced in the form of foil or powder. This kind of interlayer is easy to slip and scatter in the welding process, which reduces the welding strength of the joint. Especially in some complex structures (such as arc welding structures), it is difficult to apply the interlayer in the form of foil or powder. Therefore, it has become a key problem in the welding of complex components between WSN-HSS and WSN-HSS to prepare an intermediate layer which can effectively relieve the thermal stress of welding, completely avoid the formation of brittle intermetallic compounds and has strong structural adaptability.
With the method of electrochemical erosion in tungsten nickel and iron in situ reduction of material preparation of porous surface WNiFe layer, middle layer could obviously improve the adaptive structure, which can effectively avoid regular foil and powder form of intermediary in the complex welding structure in the process of welding, such as surface structure) prone to slip, the phenomenon such as scattered, the maximum extent to ensure the strength of joint.
