Aluminum alloy flanged pipe fittings are widely used in parts with certain requirements for medium and high strength because of their small specific gravity, good thermal conductivity, high electrical conductivity and corrosion resistance. The process characteristics of aluminum alloy heating die forging are poor fluidity, low plasticity, good thermal conductivity, narrow forging temperature range, strict requirements for initial and final forging temperatures, and the performance characteristics of heated die forging are that aluminum alloy does not produce allotropic transformation, Mainly rely on the correct control of forging mechanical parameters to improve the metal structure, so that the metal streamlines are evenly and continuously distributed along the shape of the forging to improve the mechanical properties; the quality characteristic of heated die forging is that the aluminum alloy is prone to two major quality defects of folding and cracking.

Among them, folding can reduce the bearing area of ​​parts, and it is easy to generate stress concentration during service and become a source of fatigue failure, which is very harmful. Folding waste accounts for about 70% to 80% of the total forging waste; It accounts for 5% to 10% of the total number of forging scraps. In the actual production of aluminum alloy die forgings, the quality control of the two major quality defects of folding and cracking should be based on prevention, and the combination of process technology and production management should be done in the following aspects:

(1) Necessary analysis should be carried out on the technical status of forging equipment, process equipment and billets, so that the forging process conforms to the actual production, and is advanced, reasonable, complete and accurate.
 
(2) When designing the forging die, the forming force required for the forging and the tonnage of the equipment should be considered, the volume of the blank or intermediate blank should be reasonably allocated, the correct filling method should be selected, and the fillet radius at the transition of the forging die should be increased. Or die forging slope, reduce the surface roughness value of the die cavity (including the flash bridge).
 
(3) It should be ensured that the aluminum alloy raw materials used have no defects such as folds, cracks and coarse grain rings. For billet heating, the amount of furnace charging should be strictly controlled, and the billet should be turned over in half the heating time, so as to reduce the time from furnace to forging as much as possible.

(4) During the forging operation, the deformation degree or hammering force of the billet should be correctly controlled according to the operation principle of light first and then heavy, and the anisotropy of the extruded raw materials should be reasonably used, and the forging die and operating tools should be preheated correctly. And reasonably lubricate the forging die (especially the upper die cavity).
 
(5) During the forging production, the production squad leader should be under the unified command, the first piece inspection should be coordinated by the competent technical personnel, and if necessary, follow the shift to guide the production. The quality defects of the forgings are found, and after confirming that there are no defects such as folding and cracks, the production can be evenly and rhythmically balanced within the specified time interval.
 
(6) During the inspection of forgings, the first inspection must be done, the "three inspection system" must be strictly implemented, and the process inspection, intermediate inspection, tour inspection and final inspection should be carried out to prevent systematic quality defects from flowing into the next process.