(1) Breaking the column crystal, improving macro-polarization, turning the cast-state tissue into a forged tissue, and welding the internal void under the appropriate temperature and stress conditions to improve the density of the material;
(2) The ingots are forged to form fiber tissue, and further through rolling, squeezing and forging, so that the forgings can be reasonably distributed in the direction of fiber;
(3) Control the size and uniformity of grains;
(4) Improve the distribution of the second phase (e.g. alloy carbide in the Rathic body);
(5) Make the organization get metamorphosis or metamorphosis-phase reinforcement, etc.
As a result of the above-mentioned organizational improvement, the plasticity, impact toughness, fatigue strength and durability of free forgings have also been improved, and then through the final heat forge can obtain the parts required by the hardness, strength and plasticity of good comprehensive performance. If the forging process used is unreasonable, it may produce forging defects, including surface defects, internal defects or non-conforming performance, which will affect the processing quality of subsequent processes, and some will seriously affect the performance of forgings, reduce the service life of manufactured parts, and even endanger safety.
The effect of forging tissue on the organization and performance after final heat treatment is mainly manifested in the following aspects.
(1) Non-improveable tissue defects: Auschwitz and ferrite heat-resistant stainless steel, high-temperature alloy, aluminum alloy, magnesium alloy, etc. in the heating and cooling process, there is no isomorphic transformation of materials, as well as some copper alloys and titanium alloys, etc. , in the forging process of tissue defects with heat treatment can not be improved.
(2) Can be improved organizational defects: in the general lysing structure of forged steel parts in the coarse crystal and Wei's tissue, over-co-analysis steel and bearing steel due to improper cooling caused by the slight mesh carbide, etc. in the forging heat treatment, forgings can still obtain satisfactory organization and performance after final heat treatment.
(3) Normal heat treatment is more difficult to eliminate tissue defects: for example, low-fold coarse crystal, 9Cr18 stainless steel hydraulic cylinder, H13 twin carbide, etc. need to use high temperature positive fire, repeated positive fire, low temperature decomposition, high temperature diffusion annealing and other measures to improve.
(4) Tissue defects that cannot be eliminated by general heat treatment process: serious stone and prism breaks, over-burning, ferroid belts in stainless steel, carbide nets and ribbons in the steel of the Lesanic alloy tool tools, etc., make the final heat treatment of the forging performance, or even unqualified.
(5) Organizational defects that will be further developed during final heat treatment: for example, coarse crystalline tissue in alloy-structuresteel forgings, if not improved during post-forged heat treatment, often causes the large ness and substandard performance of the Ma's needle after carbon, nitrogen co-penetration and quenching;
(6) If the heating is not proper, such as excessive heating temperature and excessive heating time, it will cause decarbonization, overheating, overburning and other defects. (7) During the process of forging cooling, if the process is not properly caused to cause cooling cracks, white dots, etc., in the heat treatment process