Precautions for heat treatment of die casting parts
(1) The heat treatment deformation of the mold is caused by the combined action of phase transformation stress and thermal stress, and is affected by many factors. Therefore, under the premise of correct material selection, attention should also be paid to the forging of the blank, and the method of six-sided forging should be used for repeated upsetting.
At the same time, in the design stage of the mold, attention must be paid to make the wall thickness as uniform as possible (process holes should be opened when the wall thickness is uneven); for molds with complex shapes, the mosaic structure should be adopted instead of the overall structure; , For sharp-cornered molds, fillet transitions should be used and the fillet radius should be increased. Data records should be made during heat treatment, the amount of deformation in each direction of length, width and thickness, and heat treatment conditions (furnace loading method, heating temperature, cooling rate, hardness, etc.), to accumulate experience for future heat treatment of molds.
(2) There are generally two technological processes for the processing of die-casting molds, which are determined according to the actual situation.
The first type: general die-casting mold.
Forging → spheroidizing annealing → rough machining → the first stress relief annealing (with a margin of 5-10mm) → rough machining → the second stress relief annealing (with a margin of 2 ~ 5mm) → finishing → the third Secondary stress relief annealing (after mold test, before quenching)→quenching→tempering→clamp repair→nitriding.
The second type: particularly complex and quenched molds that are easily deformed.
Forging → spheroidizing annealing → rough machining → the first stress relief annealing (with a margin of 5 to 10mm) → quenching → tempering → machine and electrical machining → the second stress relief annealing (with a margin of 2 to 5mm left) )→Machine and electrical machining→Third stress relief annealing (after mold trial)→Clamp repair→Nitriding.