摘要
对高耐蚀型耐候钢S450EW进行高温拉伸试验,利用光学显微镜和场发射扫描电镜对其高温热塑性进行研究。结果表明,应变速率为3×10^(-3)s^(-1)时,S450EW钢出现第Ⅲ脆性区,即塑性凹槽出现在725~775℃。应变速率为1.5×10^(-2)s^(-1)时,铸坯热塑性在整个温度区间均较高,断面收缩率大于61%。应变速率的增加改善了725~775℃的第Ⅲ类脆性区的热塑性。应变速率为3×10^(-3)s^(-1),变形温度为725℃时,断裂方式为韧性断裂;变形温度为735和775℃时,断裂方式为准解理断裂,750℃时为典型准解理断裂;变形温度为800~1250℃时,断裂方式为韧性断裂。应变速率为1.5×10^(-2)s^(-1)时,变形温度为600~700℃,断裂方式均为韧性断裂;变形温度为725和750℃时,断裂方式为准解理断裂;变形温度为800~1100℃时,断裂方式为韧性断裂。变形温度为1150℃时断裂方式为沿晶脆性断裂。对于S450EW高耐蚀型耐候钢,连铸坯在二次冷却后的矫直温度区间建议选取900~1150℃,二次冷却应保证连铸坯进矫直区的表面温度避开725~775℃的第Ⅲ类脆性区。热轧时的温度区间建议选取900~1100℃。
The high temperature tensile test was carried out for high corrosion resistance steel S450EW.The hot ductility was studied by optical microscopy and field emission scanning electron microscopy.The results show that when the strain rate is 3×10^(-3)s^(-1),the Ⅲ brittle zone appears in S450EW steel,that is,the hot ductility trough ranges from 725℃to 775℃.The hot ductility of the casting billet is high in the whole temperature range at the strain rate of 1.5×10^(-2)s^(-1),and the percentage of area reduction is more than 61%.The increase of strain rate improves the hot ductility of the Ⅲ brittle zone at 725-775℃.The fracture mode is ductile fracture when the strain rate is 3×10^(-3)s^(-1) with the deformation temperature ranging from 600℃to 725℃.The fracture mode is quasi-cleavage fracture when the deformation temperatures are 735 and 775℃.When the deformation temperature is 750℃,the fracture mode is typical quasicleavage fracture.The fracture mode is ductile fracture at the deformation temperature of 800-1250℃.The fracture mode is ductile fracture when the strain rate is 1.5×10^(-2)s^(-1) at the deformation temperature of 600-700℃.When the deformation temperatures are 725 and 750℃,the fracture mode is quasi-cleavage fracture.The fracture mode is ductile fracture at the deformation temperature of 800-1100℃.The fracture mode is intergranular brittle fracture when the deformation temperature is 1150℃.For the high corrosion resistance S450EW steel,the straightening temperature of the continuous casting billet after secondary cooling is recommended to select the temperature range of 900-1150℃.The surface temperature of the continuous casting billet into the straightening zone after secondary cooling should be ensured to avoid the Ⅲ brittle temperature zone with tempearture of 725-775℃.The temperature range recommended for hot rolling is 900-1100℃.
作者
陈继平
胡学文
钱健清
CHEN Ji-ping;HU Xue-wen;QIAN Jian-qing(School of Metallurgical Engineering,Anhui University of Technology,Ma'anshan 243002,China;Technology Center of Magang(Group)Holding Co.,Ltd.,Ma'anshan 243000,China)
出处
《塑性工程学报》
CAS
CSCD
北大核心
2021年第10期166-172,共7页
Journal of Plasticity Engineering
基金
国家自然科学基金资助项目(51774006)
高校优秀中青年骨干人才国内访学研修重点项目(gxgnfx2018005)。
关键词
耐候钢
热塑性
韧性断裂
准解理断裂
沿晶脆性断裂
weathering steel
hot ductility
ductile fracture
quasi-cleavage fracture
intergranular brittle fracture
