The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical simulator.Hot tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rat...The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical simulator.Hot tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rate of 4×10^(−3)s^(−1).The fracture behavior and mechanism of hot ductility evolution were discussed.Results showed that the hot ductility decreased as the temperature was decreased from 1000℃.The reduction of area(RA)decreased rapidly in the specimens tested below 700℃,whereas that in the specimen tested at 650℃was lower than 65%.Mixed brittle-ductile fracture feature is reflected by the coexistence of cleavage step,intergranular facet,and dimple at the surface.The fracture belonged to ductile failure in the specimens tested between 720-1000℃.Large and deep dimples could delay crack propagation.The change in average width of the dimples was in positive proportion with the change in RA.The wide austenite-ferrite intercritical temperature range was crucial for the hot ductility of medium Mn steel.The formation of ferrite film on austenite grain boundaries led to strain concentration.Yield point elongation occurred at the austenite-ferrite intercritical temperature range during the hot tensile test.展开更多
试验用Q420C钢(/%:0.18C,0.34Si,1.40Mn,0.013P,0.011S,0.066V,0.018Als,0.011 0N)铸坯的冶炼工艺为80 t BOF-LF-CC。采用Gleeble-1500D热模拟试验机测试Q420C钢连铸坯的600~1400℃热塑性,并利用金相显微镜、扫描电镜以及透射电子显微...试验用Q420C钢(/%:0.18C,0.34Si,1.40Mn,0.013P,0.011S,0.066V,0.018Als,0.011 0N)铸坯的冶炼工艺为80 t BOF-LF-CC。采用Gleeble-1500D热模拟试验机测试Q420C钢连铸坯的600~1400℃热塑性,并利用金相显微镜、扫描电镜以及透射电子显微镜分析断口形貌及金相组织和研究凝固偏析和析出物粒子对铸坯热塑性的影响。结果表明,Q420C钢第Ⅰ脆性区为>1250~1350℃;第Ⅲ脆性区为700~1050℃;在1050~1250℃,断面收缩率大于60%。工业试验结果表明,通过控制Als含量0.015%~0.020%,适当降低二冷比水量(足辊段7~8t/h,Ⅰ段5.5~6.5 t/h,托辊段14±1t/h),铸坯矫直温度≥1050℃,轧材开裂率由原45.3%降至4.6%。展开更多
基金the Fundamental Research Funds for the Central Universities,China(Nos.FRF-TP-18-039A1,FRF-IDRY-19-013)the China Postdoctoral Science Foundation(No.2019M650482).
文摘The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical simulator.Hot tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rate of 4×10^(−3)s^(−1).The fracture behavior and mechanism of hot ductility evolution were discussed.Results showed that the hot ductility decreased as the temperature was decreased from 1000℃.The reduction of area(RA)decreased rapidly in the specimens tested below 700℃,whereas that in the specimen tested at 650℃was lower than 65%.Mixed brittle-ductile fracture feature is reflected by the coexistence of cleavage step,intergranular facet,and dimple at the surface.The fracture belonged to ductile failure in the specimens tested between 720-1000℃.Large and deep dimples could delay crack propagation.The change in average width of the dimples was in positive proportion with the change in RA.The wide austenite-ferrite intercritical temperature range was crucial for the hot ductility of medium Mn steel.The formation of ferrite film on austenite grain boundaries led to strain concentration.Yield point elongation occurred at the austenite-ferrite intercritical temperature range during the hot tensile test.
文摘试验用Q420C钢(/%:0.18C,0.34Si,1.40Mn,0.013P,0.011S,0.066V,0.018Als,0.011 0N)铸坯的冶炼工艺为80 t BOF-LF-CC。采用Gleeble-1500D热模拟试验机测试Q420C钢连铸坯的600~1400℃热塑性,并利用金相显微镜、扫描电镜以及透射电子显微镜分析断口形貌及金相组织和研究凝固偏析和析出物粒子对铸坯热塑性的影响。结果表明,Q420C钢第Ⅰ脆性区为>1250~1350℃;第Ⅲ脆性区为700~1050℃;在1050~1250℃,断面收缩率大于60%。工业试验结果表明,通过控制Als含量0.015%~0.020%,适当降低二冷比水量(足辊段7~8t/h,Ⅰ段5.5~6.5 t/h,托辊段14±1t/h),铸坯矫直温度≥1050℃,轧材开裂率由原45.3%降至4.6%。
