d(mm) | 60 | da(min) | 67 |
B(mm) | 18 | Db(max) | - |
D(mm) | 95 | Da(max) | 88 |
C0r | 30500 | Grease | 8500 |
Cr | 35000 | oil | 12000 |
ra | 1 | cup | 7012 C |
New Model | NSK 7012CDT | m(kg) | 0.46 |
The quenching temperature iron should be at 820~920 DEG C, the most commonly used general factory is in the temperature between 850~900 DEG C. When the quenching temperature is too low, will cause the austenite in low carbon content, after after quenching is soft, and the martensite formation strength is also low, on the contrary if the quenching temperature is too high, austenite carbon content is too high, the danger of thermal cracking increased during quenching, the formation of residual austenite opportunity is bigger.
Cast iron after quenching essentially brittle is very high, at the same time with a high internal stress, in order to improve its hardness and toughness must be after tempering treatment, the treatment procedures and steel similar, heating rate should be lower than 100 DEG C / h, tempering temperature should be between 450~600 DEG C, tempering time is about 4 hours, tempering time too long or the temperature is too high, will be the strength and hardness decrease a lot, but can improve the elasticity, in low temperature were tempered by a long time, can cause tempering effect is quite uniform, and distribution characteristics of the whole casting is very uniform, in order to prevent stress from occurring again, especially for complicated castings, after tempering should slow cooling to 200 DEG C.
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