Cause Analysis of Microcracks in 7050 Aluminium Alloy Large Forgings
7050 aluminium alloy has excellent mechanical properties and is suitable for the manufacture of main load parts requiring high strength,high fracture toughness and resistance to stress and exfoliation corrosion.Forging manufacturing process is difficult,the process is complex,and in the manufacturing process there are a variety of defects,such as slag inclusion,pores,cracks,etc.,seriously reducing the qualified rate of products.The paper observed and analyzed the microcrack defects.The results show that:the fundamen-tal cause of the microcrack is the metal inclusion caused by insufficiently dissolved aluminium-zirconium alloy,and the crack spreads further in the forging process.In the production of 7050 aluminium alloy,when the particles of aluminium-zirconium intermediate al-loy precipitated phase(Al3Zr)are coarse and unevenly distributed,the defects of solidification structure will occur,the main reason for the aggregation defect of metallic inclusions is the inheritance of large size precipitates(Al3Zr)in Al-Zr alloys.In order to obtain Al3Zr with fine particles and uniform distribution,the agitator should be used to agitate the liquid metal,and the ultrasonic wave should be used to treat the liquid metal,so as to speed up the cooling rate of solidification.In the process of raw material inspection,ultrasonic in-spection standards should be more strict,add microstructure examination and avoid the initial microcrack defects of raw materials into production resulting in product scrap.
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维普
