回火罕有题目与处理方法(国外英文资料).docVIP

回火常见问题与解决方法(国外英文资料) Common problems and solutions? ?? ? Tempering tempering of a rift with quenching of steel material after the tempering process, due to rapid cooling, thermal shock, or organizational change and produce cracks, called tempering rift. Common high speed steel, SKD11 mould steel and other backfired hardened steel will be developed after the hot tempering. ? 100 ℃ tempering the advantages of low temperature tempering often use hot water to tempering around 180 ℃ to 200 ℃, use cooking oil tempering. In fact, if use 100 ℃ hot water for tempering, there will be many advantages, including: (1) 100 ℃ tempering can reduce the happening of the grinding crack; (2) 100 ℃ tempering can make workpiece hardness slightly increased, improve wear resistance; (3) 100 ℃ hot water tempering can reduce the chance of rapid heating produced cracks; (4) to reduce the risk of deep and cold fracture of the workpiece during the deep cold treatment, which has cushioning effect on the residues of water, increasing the material toughness; The surface of the workpiece will not produce the oil coke, the surface hardness is slightly lower, it is suitable for grinding machine, and it will not cause the oil to boil. The secondary hardening of high temperature tempering process for tool steel, residual stress and residual austenitic body all has the bad influence on steel, bath to be performed to eliminate the high temperature tempering treatment or low temperature tempering. High temperature tempering process there will be a secondary hardening phenomenon, in terms of SKD11, 530 ℃ tempering the steel hardness is slightly lower than 200 ℃ low temperature tempering, but good heat resistance, wont produce aging deformation, and can improve the heat resistant steel, more can prevent the discharge of machining deformation, there are a lot of benefits. At about 300 ℃ tempering treatment, why can produce embrittlement phenomenon? Some steel at 270 ℃ to 300 ℃ during tempering process, due t