The main factors affecting the quenching deformation of 6061 aluminum sheet are the composition of the mold steel, the original structure, the size and shape of the mold, the heat treatment process, and the condition before the mold is quenched.
1. Size and shape of 6061 aluminum plate mold The dimensional change of the mold directly affects the depth of the hardened layer, affecting the distribution of quenching stress, and distortion is inevitable. As the wall thickness of the mold increases, the distortion of the thermal stress tends to increase, and the wall thickness decreases, and the distortion of the tissue stress type tends to increase. The shape of the mold has a great influence on the quenching distortion of the mold. The symmetrical mold has small quenching distortion and certain regularity. The asymmetric mold has large quenching distortion and no regularity.
2. The heat treatment process of 6061 aluminum plate increases the austenitizing temperature, thermal stress and microstructure stress, and has a decisive influence on the proportion of martensite, retained austenite and carbide in the quenched structure. The specific volume of the phase is different. The micro-deformation quenching of the die steel controls the distortion by adjusting the austenitizing temperature. The cooling method has a relatively large influence on the quenching distortion. Reducing the cooling rate above the martensite point can reduce the distortion caused by thermal stress; lowering the cooling rate below the martensite point can reduce the distortion caused by the tissue stress. Both grading and austempering reduce thermal stress and tissue stress and reduce quenching distortion.
3. The original structure of 6061 aluminum plate The original structure of the die steel also has a certain influence on the quenching distortion of the die steel. The quenching distortion of the original microstructure is spherical pearlite or quenched and tempered structure is smaller than that of the original structure is lamellar pearlite. The carbide segregation in the die steel causes the quenching distortion to be directional, and the expansion amount in the direction of the strip-shaped carbide is larger than the vertical strip direction.
4. Before the quenching of 6061 aluminum plate molds Mechanical processing, plastic forming, welding and straightening before quenching will cause residual internal stress in the mold. If the stress is not removed, the distortion will be caused by the relaxation of residual internal stress during quenching heating. In addition, improper quenching of the mold or poor fixture and the self-weight of the die steel may cause significant distortion during quenching and heating.
5. The higher the carbon content of the 6061 aluminum plate, the greater the phase transformation stress of the die steel, and the more severe the quenching distortion of the die. The mold steel containing alloying elements and high alloying elements has a higher phase transformation stress and thermal stress, and the mold quenching distortion is severe.