Study On Microscopic Structure And Process Of Cladding Aluminum Alloy By High Frequency Induction Welding

At present, with the rapid development of modern industry, energy, environmental and ecological problems have become the world’s trend of the development of the automotive lightweight. Cladding aluminum alloy tube, which has been widely used in automotive heat exchangers, instead of the traditional copper alloy heat exchanger, in response to the call of the national energy conservation and emissions reduction. Commonly, coating aluminum alloy tube are mainly aluminum alloy seamless drawn pipe and welded pipe on the market. This aluminum alloy tube with the radiator assembly, resulting in heat exchanger quality is not stable. In the last century, abroad has to apply high frequency induction welding technology to thin-walled aluminum alloy connection. In the domestic, enterprises which produce aluminium alloy high-frequency welded tube mainly are minority several independent research and imported production line. These are not sufficient to meet the market demand. Using high frequency induction welding technology of thin-walled aluminum alloy welded tube connection, can not only get high efficiency, excellent quality of welded pipe, but also the choice of process parameters and control more automation. But three layer cladding aluminum alloy material main alloying element is different performance, the organization directly affects the quality of welded tube. So the research of the high frequency induction welding during the welding process and the relationship between the organization and performance is necessary.This topic research the high frequency induction welding technologies apply on cladding aluminum alloy tube connection. The connection between welding process parameters(welding speed, welding power, welding frequency) and welded pipe three layer structure and mechanical properties is researched.This paper adopts the metallographic electron microscope, scanning electron microscope(SEM), microhardness, electrochemical corrosion experiment means.Last, the conclusion are as follows:(1)The welding speed and welding power have great influence on the microstructure and mechanical properties of aluminium alloy welded tube. As the gradually increase of the parameters, the change-law of the microstructure and mechanical properties of welded tube is parabolic. And both of them influence each other, when they meet certain cooperate relationship, microstructure and properties of the welded tube can get optimal.(2)Cladding aluminum alloy tube has different weld defects on each layer. Due to the diffusion of Si elements, weldability of outer AA4343 materials will be affected. Because of the nature of Mn element segregation the middle layer AA3003 may form segregation organization.(3)Microhardness of welded tube’s longitudinal and transverse present the same results, three regions of weld(weld center surface, heat affected zone and base area) maintain the microhardness of basic level, and the numerical is different. The highest –microhardness-zone is heat affected zone, which is about 67 HV. Hardness value of the minimum weld center is 48 HV, and hardness value is 60 HV in matrix.(4)Under the premise of qualified organization and other mechanical performances, welding speed and welding power still affect the corrosion of resistance weld cladding. But the influence of the welding power effect is more obvious. So on the premise of guarantee the quality of welded pipe, corrosion resistance of high-speed welded tube is better.