The existence of defects in forgings may affect the quality of processing or processing in subsequent processes, and some seriously affect the performance and use of forgings, or even greatly reduce the service life of the manufactured parts and endanger safety. Therefore, in order to ensure or improve the quality of forgings, in addition to strengthening the quality control in the process and taking corresponding measures to prevent the occurrence of defects in forgings, the necessary quality inspection should be carried out to prevent the subsequent processes (such as heat treatment, surface treatment, cold working). And forgings with defects that have a bad influence on the use performance flow into subsequent processes. After quality inspection, remedial measures can also be taken on the forged parts according to the nature of the defect and the degree of influence on the use to make it meet the technical standards or the requirements of use.
Therefore, the quality inspection of forgings is, in a sense, the quality control of the forged parts on the one hand, and the improvement direction of the forging process on the other hand, so as to ensure that the quality of forgings meets the requirements of forging technical standards and meets the design, Processing and use requirements.
The following points need to be paid attention to during the forging process of upsetting forgings. If it is not proper, it may affect the quality of forgings. Let me take a look next.
Forging process generally consists of the following processes, namely blanking, heating, forming, cooling after forging, pickling and heat treatment after forging. If forging process is improper during the forging process, it can cause a series of forging defects.
The heating process includes furnace temperature, heating temperature, heating speed, holding time, furnace gas composition, etc. If the heating is not proper, such as excessive heating temperature and excessive heating time, it will cause decarburization, overheating, overheating and other defects.
For blanks with a large cross-section scale, poor thermal conductivity and low plasticity, if the heating speed is too fast and the holding time is too short, the temperature distribution is often uneven, causing thermal stress and cracking the blank.
The forging process includes deformation mode, degree of deformation, deformation temperature, deformation speed, stress state, conditions of the tool and die, and lubrication conditions. If the forming process is improper, it may cause coarse grains, uneven grains, various cracks, and cracks. Stacking, flow through, vortex, as-cast structure residue, etc.
In the cooling process after upsetting, improper process may cause cooling cracks, white spots, and reticulated carbides. For these several forging processes, special attention must be paid to the forging process, so as to better ensure the quality of the forgings.