key points of heat treatment of aluminum extrusion die

1. The quality of heat treatment of aluminum extrusion die directly affects the service life of the extrusion die, and the mold is tempered many times after quenching "+" to meet the hardness requirements. Quenching is to improve the hardness of the mold, and repeated tempering is to improve the toughness of the mold and stabilize the internal structure. The hardness value of mold heat treatment is specified: large aluminum extrusion die (F>500mm), HRC45-48; Medium mold (F300~500mm), HRC47-50; Small Extrusion Die (F<300mm), HRC48-51; Three points are tested on the same plane of a set of molds, and the hardness value of each point should be qualified within the specified range.

2. Special attention should be paid to several points in the heat treatment process of the extrusion die:

a. The heating speed of the high-temperature section should be fast, and the holding time should not be too long, so as to prevent the extrusion die from overheating or overheating, overheating - coarse grains, overheating - low melting point elements and inclusions will cause dissolution;       

b. After quenching, the aluminum extrusion die should be tempered in time to prevent cracks;       

c. When the hardness of the extrusion die is found to be insufficient or uneven after heat treatment, annealing should be carried out, and the heat treatment should be re-carried out according to the process (when the hardness value is < HRC35, it can be directly heat-treated, without annealing);       

d. For large aluminum extrusion molds or finished molds with complex cavities, a stress-relieving tempering process should be added (to eliminate electrical processing and machining stress, that is, to eliminate thermal stress and microstructure stress);       

e. The temperature of the quenching oil of the mold should be 100°C to ensure the quenching effect.