焊管2026，Vol.49Issue(8)：33-42,51,11.DOI:10.19291/j.cnki.1001-3938.2026.08.004
微量Mg处理X70管线钢热影响区应力腐蚀行为与机理研究
Study on Stress Corrosion Behavior and Mechanism of X70 Pipeline Steel Heat-affected Zone with Micro-Mg Treatment
摘要
Abstract
To develop high-performance pipeline steel with excellent resistance to stress corrosion cracking(SCC),three typical heat-affected zone(HAZ)microstructures(intercritical HAZ,fine-grained HAZ and coarse-grained HAZ)of conventional X70 pipeline steel and micro-Mg treated X70 steel were prepared via thermal simulation.The effects of micro-Mg treatment on the SCC behavior of X70 steel welds were investigated through microstructure characterization,slow strain rate tensile test(SSRT)and impact test.The results indicate that the stress corrosion cracking susceptibility of the base metal and weld zone of X70 pipeline steel in low-temperature seawater environment follows the order:coarse-grained HAZ>fine-grained HAZ>base metal>intercritical HAZ.Micro-Mg treatment can effectively improve the SCC resistance of the base metal and weld zone of X70 pipeline steel.The addition of micro-Mg promotes the formation of a large number of micro-nano sized and diffusely distributed inclusions in the steel,which are mostly spherical or elliptical composite inclusions with MgO·Al2O3 as the core.These inclusions significantly inhibit the initiation and propagation of SCC cracks in the base metal and weld zone by pinning austenite grain boundaries,inducing the nucleation and growth of acicular ferrite,and refining the microstructure.The research results can provide experimental basis for the design and performance control of high-performance high-strength acid-resistant steel.关键词
微量Mg处理/X70管线钢/焊接热影响区/应力腐蚀开裂Key words
micro-Mg treatment/X70 pipeline steel/weld heat-affected zone/stress corrosion cracking分类
矿业与冶金引用本文复制引用
杨广明,宁峰,耿会坡,张瑞奇,王胤森,李宁宁,刘智勇,李晓刚..微量Mg处理X70管线钢热影响区应力腐蚀行为与机理研究[J].焊管,2026,49(8):33-42,51,11.基金项目
国家市场监督管理总局科技计划项目"高强钢管道应力腐蚀开裂在线评价方法与测试装置研究"(项目编号2024MK011) （项目编号2024MK011）
国家自然科学基金"基于氧化物冶金微量Mg处理高钢级厚壁抗酸管线钢抗H机制及应用基础"(项目编号U21A20113). （项目编号U21A20113）
