機械專業(yè)畢業(yè)設計--外文資料和翻譯-其他專業(yè)(編輯修改稿)
2025-02-24 12:28 本頁面
【文章內(nèi)容簡介】 e cooling speed depends on the temperature and hardened steel quenching medium heat can be taken away from the surface of the ability of heat transfer and steel itself. Table 111 is some mon medium and cooling method, cooling ability of the sequence. High temperature gradient produces high stress, deformation and cracking causes, 畢業(yè)設計說明書 29 so only in the very need to produce quenching specific structures are used. When the quenching heat uniform, care must be taken to reduce the heat stress diffusion. For example, a thin stick to end its vertical quenching, is inserted into the cooling medium, so whole section and temperature changes. If the shape of a side of the workpiece cooling, and on the other side of the earlier than size change is likely to cause high stress, produce plastic flow and permanent deformation. With several special quenching method can reduce stress, deformation and cracking quenching decreases. One called hierarchical quenching, the method is: will the austenitic steel in temperature is higher than that of martensite transformation temperature (Ms), salt bath time until the temperature uniformity, at the beginning of forming bainite, then put before air cooling, heat generated from the start when the same hardware quenching cracking, martensite and warpage cause of high thermal stress or eliminate stress have been quenched. In a similar method of temperature, then, is called the isothermal quenching (austenitic steel in salt bath), keep for a long time, the result is formed with the isothermal bainite. Bainite structure in the same ingredients as the formation of martensite hard, but in normal hardened steel, reduce the heat shock, by further processing, unnecessary in high hardness can be obtained when good impact toughness. Five, tempering To adjust hardened steel used the third step is often backfire. Besides the isothermal quenching steel quenching condition usually used in most all can use in production. To produc
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