Cold-drawn steel pipes are mostly medium and high carbon alloy steels. After quenching, some undercooled austenite does not transform into martensite, and retains as retained austenite in service state, which affects service performance. Preventive measures: (1) Boiling cold-drawn steel tube in boiling water for 30-60 minutes before quenching can eliminate 15%-25% internal stress and stabilize retained austenite, then conventional cooling treatment at - 60 degrees Celsius or deep cooling treatment at - 120 degrees Celsius. The lower the temperature, the more retained austenite transforms into martensite, but it is impossible to complete the transion. The experiment shows that about 2% retained austenite transforms into martensite. The retained austenite retains between%-5% and retains a small amount of residual austenite to relax stress as needed. Its cushioning effect is that retained austenite is soft and tough, which can partly absorb the rapidly expanding energy of martensitization and alleviate the phase transion stress. If the retained austenite is cooled below zero, the martensitic transion of retained austenite can occur. Therefore, the essence of cooling treatment is to continue quenching. The superposition of quenching stress at room temperature and quenching stress at zero degree results in the ion of cold treatment cracks when the superposition response exceeds the strength limit of the material.
(2) After the cold treatment, the cold-drawn steel pipe is taken out and heated in hot water, which can eliminate 40%-60% of the cold treatment stress. When the temperature rises to room temperature, it should be tempered in time. The cold treatment stress should be further eliminated to avoid the ion of cold treatment cracks, obtain stable structure and properties, and ensure that no distortion occurs in the storage and use of cold-drawn steel pipe products.无锡鑫盛源钢管有限公司专业生产:方管,矩形管,焊管等一系列高频焊管产品,方管规格：40～200之间任意变形,矩形管规格：50～200之间任意变形,圆管规格：50～200之间任意变形.方管按生产标准分:国标方管,日标方管,英制方管,美标方管,欧标方管,非标方管等.方管价格,矩形管价格,焊管价格.方管行情,矩形管行情,焊管行情.行业资讯
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