Request for non-standard screw heat treatment
When customizing non-standard screws, if the material requested by the customer does not meet the required strength, the screw manufacturer will advocate strengthening the hardness of the non-standard screws through heat treatment. If the hardness requirement for non-standard screws is high and the material itself cannot meet the requirement, heat treatment methods are required. So, what are the requirements for heat treatment methods for non-standard screws? Screw manufacturers will briefly introduce them here:
Grade 1 and Grade 2 non-standard screws produced from medium carbon steel, medium carbon alloy steel, and martensitic stainless steel medium carbon steel should be processed by hot forging or cold forging, or by hot forging, hot rolling, or cold drawing bar cutting. Non standard screws are divided into three main parts: size, mechanical properties, and surface defects. The specific inspection items for each section have different regulations based on different products. Grade 1 and Grade 2 non-standard screws cut from cold forged or cold drawn bar materials should be annealed to relieve stress, with an annealing temperature of 1000 degrees Celsius. F(538。C)。 Grade 1 and Grade 2 non-standard screws that are hot forged or cut from hot-rolled bar material do not require annealing for elimination
Non standard screws of grades 2H, 2HM, 3, 4, 6, 6F, 7, 7M, and 16 should be hot forged or cold forged, or machined using hot forged, hot rolled, or cold drawn bar materials. Non standard screws are divided into three main parts: size, mechanical properties, and surface defects. The specific inspection items for each section have different regulations based on different products. Then heat treatment is carried out to achieve the specified mechanical function requirements. These grades of non-standard screws should be reheated above the critical temperature of the material and quenched and tempered in an appropriate medium. The tempering temperature should not be lower than the specified value in Table 2-2-70
Non standard screws processed by heat treated bar cutting do not require re heat treatment. Non standard screw customization inspection method: The inspection method for standard fasteners is specified in the technical specifications of the product. And professional standards have been established for the testing methods of fasteners (size and geometric accuracy). For non-standard screws of 2HM and 7M grades, stress should be eliminated after the ultimate realization of forming, cutting, tapping and other processes. The temperature for stress relief should not be lower than the tempering temperature, so stress relief is actually a tempering treatment. Non standard screws of grade 6 and 6F should be tempered, and the tempering temperature should be maintained for at least 1 hour
(2) Austenitic stainless steel shall be preceded by the functional grade symbol. 8. Or. 9. Non standard screws such as Grade 8, 8 Ren Grade, 8M Grade, 8T Grade, 8F Grade, L ü P Grade, L ü N Grade, 9C Grade, etc. should be hot forged or stunning, or processed by hot forging, hot rolling, or cold drawing rod cutting. Non standard screws such as 8-grade, 8CA grade, 8M grade, L ü ding grade, etc; Hot forging or cold heading, or using hot forging, hot rolling, or cold drawing to cut bar materials. And heat the non-standard screws to a certain temperature and adhere to sufficient [1, flil] to dissolve the chromium carbide. Then cool at a certain speed to prevent carbides from precipitating again.
4. Mechanical function
(l) After hardness heat treatment, the hardness of all non-standard screws with W energy level at room temperature should meet the specified requirements. 2HM and 7M non-standard screws, each non-standard screw should undergo Brinell or Rockwell hardness testing and comply with regulations. For non-standard screws of grades 1, 2, 2 days, 2HM, 3, 4, 7, 7M, and 16, the minimum hardness test after re tempering should be conducted, and the re tempering hardness value specified in Table 2-2-71 should be achieved. Another one. Fire hardness testing is a process of randomly selecting a sample of non-standard screws of various functional levels after heat treatment according to their diameter specifications. The sample is heated to a designated temperature and kept warm for 24 hours before slowly cooling to room temperature. After that, hardness testing is performed.
