铸锭加热和锻后热处理工艺对18CrNiMo7-6钢Ф540mm棒材带状的影响

Effect of Ingot Heating and Forged Products Heat Treatment Process on Banded-Structure of Фφ540 mm Bar of Steel 18CrNiMo7-6

试验18CrNiMo7-6重型齿轮钢(/%:0.165C,0.59Mn,0.24Si,0.006S,0.008P,1.56Ni,1.71Cr,0.28Mo,0.034M,0.0129N)的生产流程为60 t UHP EAF-LF-VD-12.5 t铸锭工艺。试验研究了钢锭加热工艺(1 200~1 220℃,7-8 h^13-15 h),锻材完全退火(900℃12 h,≤80℃/h至650℃50 h,空冷)、等温退火(900℃12 h,空冷至650℃50 h,空冷)和正火(900℃12 h,空冷)工艺对Φ540 mm锻材带状组织的影响。结果表明,钢锭1 200~1 220℃7-8 h加热,锻材经完全退火、等温退火或正火处理后其带状级别分别为4.0,3.5和3.0,钢锭经1 200~1 220℃13-15 h加热,锻材经正火处理后其带状级别为2.5,为最佳工艺。

Process flowsheet of test heavy gear steel 18CrNiMo7-6（/%：0.165 C,0.59 Mn,0.24 Si,0.006 S,0.008 P,1.56 M,1.71 Cr,0.28 Mo,0.034A1,0.012 9N） is 60 t UHP EAF-LF-VD-12.5 t ingot casting process.The effect of ingot heating process（1 200 - 1 220 ℃,7-8 - 13-15 h）,forged product complete annealing（900 ℃ 12 h,with≤80 ℃/h slow cooling to 650℃ 50 h,air cooling）,isothermal annealing（900 ℃ 12 h,air cooling to 650 ℃ 50 h,air cooling） and normalizing（900 ℃ 12 h,air cooling） process on banded structure of φ540 mm forged bar has been tested and studied.Results show that as ingot heating at 1 200 - 1 220 ℃ for 7-8 h,the rating of banded-structure of forged bar by complete annealing,isothermal annealing or normalizing process is respectively 4.0,3.5 and 3.0,while as ingot heating at 1 200 - 1 220 ℃ for 13-15 h,then normalized,the rating of banded-structure of forged bar is 2.5,it is an optimum process.