镜面塑料模具钢P80R热轧扁材表面裂纹分析和工艺改进

An Analysis on Surface Crack of Hot-Rolled Flat Products of Mirror Plastic Die Steel P80R and Process Improvement

P80R钢扁材(/%:0.15C,0.25Si,1.70Mn,0.012P,0.002S,3.01Ni,0.34Mo,1.07Cu,1.10A1)的生产流程为110 t LD-LF-RH-4.2 t铸锭-初轧开坯150 mm×615 mm扁材-轧成60 mm×610 mm扁材。经检验和分析得出,裂纹附近Ni,Cu严重富集,其Ni含量和Cu含量分别达32.55%~33.53%和7.97%~8.86%,Cu的富集导致表面晶界氧化,形成裂纹,应控制钢中Cu含量、加热温度和时间。通过将钢中Cu含量从1.07%降至0.92%,Al含量由1.10%降至0.88%,Ni/Cu由2.7增加至3.3,1 100~1 140℃加热保温时间由30~50 min降至20~30 min,钢坯进行剥皮处理等工艺措施,镜面塑料模具钢P80R扁材裂纹出现率由70%降至≤0.5%。

The production flowsheet of steel PSOR flat products （/% ： 0. 15C, 0. 25Si, 1.70Mn, 0. 012P, 0. 002S, 3.01Ni, 0. 34Mo, 1.07Cu, 1.10A1） is ll0 t LD-LF-RH-casting 4. 2 t ingot-breakdown 150 mm x615 mm slab-rolling to 60 mm x 610 mm fiats. It is obtained by examination and analysis that the Ni and Cu is seriously enriched near the cracks, the Ni content and Cu content in area near cracks are respectively up to 32. 55% -33.53% and 7. 97% - 8.86% , and the enrichment of Cu leads to surface grain boundary oxidation to form cracks, therefore the Cu content in steel, slab heating temperature and time should be controlled. By the process measures including decreasing Cu content in steel from 1.07% to 0. 92% , A1 content in steel decreasing from 1.10% to 0. 88% , increasing Ni/Cu from 2. 7 to 3.3, reducing heating time at 1 100 - 1 140 - from 30 - 50 rain to 20 N 30 min and slab peeling treating, the occurrence rate of surface cracks of mirror plastic die steel P80R fiats decreases from 70% to -〈0. 5%.