不同热处理状态下的MA带状组织对管线钢抗HIC性能的影响

Effect of MA banded microstructure under different heat treatment states on HIC resistance of pipeline steel

研究了不同轧制及热处理工艺对含碳0.13%管线钢中MA(马奥岛)组织形成及消除规律的影响,并分析了MA带状组织对试验钢抗氢致裂纹(HIC)性能的影响。结果表明,MA带状组织能显著降低试验钢板的抗HIC性能;通过高温回火,MA带状组织会大部分分解,抗HIC性能得到改善,特别是裂纹厚度率大幅降低;通过正火并完全奥氏体化,钢中不均匀的溶质元素扩散均匀,相变后转变为细的铁素体+珠光体组织,虽然仍存在细的珠光体带,但仍可以获得较好的抗HIC性能;通过正火+回火处理,可以消除由于正火奥氏体化不充分导致的MA带,且细珠光体带状呈现断续分布的特征,组织均匀性及抗HIC性能得到进一步提升。

Formation and elimination of MA microstructure in pipeline steel with 0.13%C under different rolling and heat treatment processes were studied,and the effect of MA banded microstructure on the hydrogen induced cracking(HIC)resistance of the steel was analyzed.The results show that the MA banded microstructure has a significant HIC resistance of the tested steel plate.By high⁃temperature tempering,the MA banded microstructure can be largely decomposed,and the HIC resistance is improved,especially with a significant reduction in crack thickness rate.After normalizing and fully austenitizing,the uneven distributed solute elements in the steel diffuse evenly,and the microstructure transforms into fine ferrite+pearlite structure after phase transformation.Although there is still fine pearlite bands,good HIC resistance can still be obtained.By normalizing and tempering treatment,MA bands caused by insufficient normalizing and austenitizing can be eliminated,and the fine pearlite bands exhibit intermittent distribution characteristic,thus the uniformity of the microstructure and HIC resistance can be further improved.