800 MPa级耐酸管线钢高温热塑性研究

Hot ductility of 800 MPa acid-resistant pipeline steel at high temperature

以一种800 MPa级耐酸管线钢铸坯为研究对象,采用Gleeble 3500试验机对其高温力学性能进行测试,运用金相显微镜、体视显微镜、扫描电镜及显微硬度计,对实验钢拉断后的微观组织、断口形貌及显微硬度进行表征。结果表明,在600~1000℃温度范围,实验钢种的断面收缩率均大于70%,表现出了较好的高温热塑性,但热塑性曲线在700~850℃之间出现了塑性低谷区,这与原始奥氏体晶界处先共析铁素体网膜的析出有关,故铸坯矫直温度选择应避开该温度区间。此外,实验钢还具有较好的高温强度,600℃下抗拉强度可达353 MPa。

In this paper,the high-temperature mechanical properties of as-casted 800 MPa acid-resistant pipeline steel were tested by Gleeble 3500 thermal simulator.The microstructure,fracture morphology and microhardness of hot tensile samples were characterized by optical microscope,stereomicroscope,scanning electron microscope and microhardness tester.The results indicate that the 800 MPa acid-resistant pipeline steel has good hot ductility in the temperature range of 600~1000℃,and the section shrinkage rate is larger than 60%;however,there is a relatively low plastic valley at 700~850℃,which is related to the precipitation of pre-eutectoid ferrite retina at the grain boundary of original austenite.Therefore,the straightening temperature of the slab should not be in this temperature range.In addition,the acid-resistant pipeline steel has great high temperature strength,and the tensile strength reaches 353 MPa at 600℃.