The influence of the structure on the structure and performance after heat treatment is mainly explained in the following aspects
(1) Structural defects that cannot be improved by forgings manufacturers: austenitic and ferritic heat-resistant stainless steels, high-temperature alloys, aluminum alloys, magnesium alloys, etc., during heating and cooling, there is no homogeneous transformation of the material, and a little copper Alloys, titanium alloys, etc., the structural defects occurring during the casting process are not improved by heat treatment.
(2) Improved structural defects: coarse grain and Wei's structure in general overheated layout steel forgings, superfine eutectoid steel and bearing steel due to improper cooling caused by light and fine mesh carbides, etc. At the time of disposition, the forged piece can still obtain freehand construction and performance after heat treatment.
(3) The normal heat treatment is difficult to eliminate structural defects: for example, low-magnification coarse crystal, 9Cr18 stainless steel, H13 twinned carbide, etc., need to use high-temperature normalizing, repeated normalizing, low-temperature interpretation, high-temperature dispersion annealing, etc. Improved.
(4) Structural defects that cannot be eliminated by the general heat treatment process: tight stone fractures and facet fractures, over-burning, ferrite belts in stainless steel, carbide nets and belts in Leysite alloy tool steels, etc. The performance of forgings after heat treatment is degraded, and even divergent.
(5) Structural defects that will be further developed in the case of heat treatment: For example, the coarse-grained structure in the alloy layout steel forgings is not improved when hot after forging, and often causes Markov after carbon, nitrogen co-infiltration and quenching. Large body needles and performance differences; coarse banded carbides in high-speed steel, quenching often cause cracking.
(6) If the heating is improper, for example, the heating temperature is too high and the heating time is too long, it will cause defects such as decarburization, overheating and overburning.
(7) During the post-forging cooling process, if the process is improper, it may cause cooling cracks, white spots, etc., and crack during the heat treatment.