Screw heat treatment (chǔ lǐ) requirements
When custom-made screws, when the quality of the material required by the customer to meet the customer's requirements does not meet the strength, then screw manufacturers will suggest that the screw through the (tōng guò) heat treatment (chǔ lǐ) approach to enhance the hardness of the screw. If the screw hardness requirements are relatively high, and the material itself can not meet the requirements, you need to do the heat treatment, then what are the requirements of the screw heat treatment? Screw manufacturers here to briefly explain
The Grade 1 and Grade 2 screws used in the production of carbon steel in medium carbon steel, alloy steel, and martensitic stainless steel (stainless acid-resistant steel) should be hot forged or cold forged or hot forged or hot rolled. Or cold-drawn bar cutting. The grade 1 and grade 2 screws for cold forging or cold drawing should be annealed to eliminate stress. The annealing temperature should be 1000 more. F (538. C). Hot-forged or Grade 1 and 2 screws cut with hot-rolled bars without annealing
Two 2H, 2HM, 3, 4, 6, 6F, 7, 7M, and 16 screws should be hot-forged or cold-headed, or hot forged, hot-rolled, or cold drawn bar stock. Precision Screws Small screws, also known as tiny screws, are tiny fasteners that connect the material of the product. They are tiny in shape, but they can play a key role in the production of key parts. Widely used in electronics, electrical, electrical appliances, furniture, machinery and equipment. It is then heat-treated to meet the specified mechanical performance requirements. These grades of screws should be reheated above the critical temperature of the material and quenched and tempered in the appropriate medium, the determinant. The tempering temperature should not be less than that specified in Table 2-2-70.
Screws that have been heat-treated (bars) do not require reheating. For 2HM and 7M class screws, the stress should be removed after the final completion of the forming, cutting, tapping (tool: tap or tap) process. The stress relief temperature should not be lower than the tempering temperature, so the elimination of stress is actually a tempering treatment. Grade 6 and 6F screws should be tempered and at least 1 h at tempering temperature
(2) Stainless steel (stainless acid-resistant steel) Stainless steel performance level symbol is added in front of it. 8. or. 9. 8th, 8th, 8M, 8T, 8F, Lu P, Lu N, 9C and other screws, should be hot or cold proud, or use hot forging, hot-rolled or cold-pull bar cutting Processing. 8th, 8CA, 8M 8, Luding 8, etc.); hot forging or cold forging, or hot forging, hot rolling or cold-pull bar cutting plus one. The screws are heated to a certain temperature to maintain sufficient [1, flil] to dissolve the chromium carbide. It is then cooled at a rate to prevent the redeposition of carbides.
4. Mechanical properties
(l) Hardness after heat treatment (chǔ lǐ), at room temperature, all "W-grade screw hardness should meet the requirements (guī dìng). Stainless steel screw refers to the screw shape made of stainless steel screw wire piercing, after the good teeth The thread is made of stainless steel.The stainless steel screws are divided into stainless steel SUS201 screws, stainless steel SUS304 screws, and stainless steel SUS316 screws.Stainless steel screws usually refer to steels that resist the corrosion of air, water, acids, alkali salts or other media. The composition of the alloy is different, with emphasis on stainless and acid resistance, respectively.Some steels are not necessarily acid-resistant, but acid-resistant steels are usually non-rust.2HM and 7M screws, each screw should be clothed Rockwell or Rockwell hardness testing, and all should be in accordance with regulations. For grade 1, 2, 2nd, 2HM, 3, 4, 7, 7M, and 16 screws, should be re-tempered Minimum hardness test, and should reach the re-tempered hardness value specified in Table 2-2-71.Then, the fire hardness test is to randomly sample a piece of screw with various performance levels after heat treatment (chǔ lǐ). Heating gauge Temperature, and after 24 h incubation was slowly cooled to room Ying, then hardness testing