2Cr12NiMo1W1V不锈钢Φ180 mm棒材低倍中心黑色区缺陷分析和退火工艺改进

An Analysis on Macrostructure Central Dark Zone Defect of Φ180 mm Bar of Stainless Steel 2Cr12NiMoW1V and Annealing Process Improvement

2Cr12NiMo1W1V钢Φ180 mm棒材的生产工艺流程为80 t BOF-VD-LF-ESR 6 t锭-锻造-900℃退火。2Cr12NiMo1W1V不锈钢棒材成品低倍组织中出现GB/T1979-2001《结构钢低倍组织缺陷评级图》中无对应类型的中心黑色腐蚀区域缺陷,分析得出,该钢退火后的正常组织为铁素体基体+碳化物,而中心区域为板条马氏体+托氏体,托氏体耐腐蚀性差,形成黑色区域。将原先的退火工艺优化为900℃-700℃等温退火工艺,可保证全截面组织的均匀转变。该工艺可消除和避免2Cr12NiMo1W1V钢棒材中心黑色区域。

The production process flowsheet of Ф180 mm bars of steel 2Cr12NiMol W1V is 80 t BOF-VD-LF-ESR 6 t ingot-forging-900 ℃ annealing. The central dark zone defect which un-corresponding to GB/T 1979-2001 ＂Standard dia- gram for Macrostructure and Defect of Structural Steels＂ occurs in macrostructure of stainless steel 2Crl2NiMolW1V fin- ished products. By analysis it is obtained that the normal structure of the annealed steel is ferrite matrix ＋ carbide, while the structure in central zone is lath martensite ＋ troostite, the corrosion resistance of troostite is poor to form dark etched zone. The original annealing process is optimized to 900 ℃ -700 ℃ isothermal annealing process it shall be to ensure homo- transformation of structure in whole section of bar, this process can eliminate and avoid the formation of bar central dark zone of steel 2CrI2NiMolW1V.