厚规格X80管线钢高温屈服强度及卷取工艺分析

High Temperature Yield strength and Coiling Process Analysis of Thick X80 Pipeline Steel

通过高温拉伸试验研究了厚规格X80管线钢的高温力学性能,分析了不同温度的高温拉伸试样的组织,确定了卷取野热头冶温度控制范围。结果表明X80管线钢的高温屈服强度受温度影响明显,当温度由550℃升高到700℃时,屈服强度由488 MPa降低到240 MPa;组织由原始轧态的针状铁素体变为粒状贝氏体,同时析出相长大,位错密度降低。对于厚规格高级别管线钢而言,卷取时野热头冶温度应控制在600-650℃。

High temperature mechanical properties of thick X80 pipeline steel were studied by the high temperature tensile experience. The mircrostructures of high temperature tensile specimens at different temperatures were analyzed. The control range of ＂hot head＂ coiling temperature was ascertained. The results show that high temperature yield strength of X80 pipeline steel is significantly affected by temperature. The yeile strength reduces from 488MPa to 240MPa when the temperature increases from 550℃ to 700℃. The microstructure changes from the original acicular ferrite to granular bainite. at the same time, the precipitated phase grows up and the dislocation density decreases. For high grade pipeline steel with thick specification, the ＂thermal head＂ temperature should be controlled between 600 and 650℃ during coiling.