摘要
采用Gleeble-1500热模拟机研究了09MnNiDR钢的高温力学性能,得到600~1 350℃范围内试样的断面收缩率、抗拉强度和应力应变曲线,并结合扫描电镜(SEM)观察断口形貌和FactSage软件进行凝固相分析。结果表明,该钢种的第Ⅰ高温脆性区为液相线温度(t^(1))到1 350℃,高温塑性区为1 350~950℃,第Ⅲ低温脆性区为950~600℃。高温塑性区为奥氏体区,具有良好塑性,但高温抗拉强度较低;第Ⅲ低温脆性区塑性降低,是由于950℃以下奥氏体向α-铁素体转变。从断口形貌观察可知,高温塑性区主要为穿晶断裂,第Ⅲ低温脆性区主要为沿晶断裂,同时在高温塑性区断口观察到液态夹杂物MnO-SiO_(2)-Al_(2)O_(3),结合三元相图可知析出夹杂物熔点低于1 300℃。为得到低熔点塑性好的夹杂物,应控制MnO与SiO_(2)的比例在1~1.5左右,同时Al_(2)O_(3)的质量分数控制在10%~17%,降低连铸过程中产生内部裂纹的风险。
High temperature mechanical properties of 09 MnNiDR steel were investigated on Gleeble-1500 thermal simulation testing machine. The percentage of section shrinkage, tensile strength and stress-strain curves were obtained within the temperature range of 600-1 350 ℃, and the fracture morphology was analyzed with the help of scanning electron microscope(SEM). Solidification phase transition was calculated by FactSage software. The results show that the high temperature interval of brittleness(Ⅰ) starts from liquidus temperature(t_(1)) to 1 350 ℃, afterwards following with the high temperature interval of plasticity from 1 350 to 950 ℃, and the third area from 950 to 600 ℃ is the low temperature interval of brittleness(Ⅲ). The high temperature interval of plasticity is related to the austenite phase with great plasticity, while the high temperature tensile strength is low;the reason for the decrease of plasticity in the low temperature interval of brittleness(Ⅲ) is attributed to the γ→α phase transition when temperature lower than 950 ℃. The observation of fracture morphology showed the high temperature interval of plasticity is transcrystalline rupture and the low temperature interval of brittleness(Ⅲ) is intergranular fracture. Meanwhile the liquid inclusion MnO-SiO_(2)-Al_(2)O_(3) was observed on the fracture morphology of the high temperature interval of plasticity. Based on ternary phase diagram calculation, the melting point of inclusion is less than 1 300 ℃. In order to control the inclusion with low melting, the ration of MnO/SiO_(2) should be controlled between 1 and 1.5, while the content of Al_(2)O_(3) is from 10 mass% to 17 mass%, so as to reduce the risk of internal cracks during continuous casting.
作者
丁航
魏康吉
杨勇
曾凡政
王丽君
周国治
DING Hang;WEI Kangji;YANG Yong;ZENG Fanzheng;WANG Lijun;CHOU Kuochih(Collaborative Innovation Center of Steel Technology,University of Science and Technology Beijing,Beijing 100083,China;Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411100,Hunan,China)
出处
《钢铁研究学报》
CAS
CSCD
北大核心
2022年第5期470-477,共8页
Journal of Iron and Steel Research
基金
国家自然科学基金资助项目(51922003)
中央科研基本业务费资助项目(FRF-TP-19-004C1)。
关键词
低温容器钢
高温力学性能
断口形貌
FactSage
cryogenic vessel steel
high temperature mechanical property
fracture morphology
FactSage
