随着碳捕集、利用与封存(carbon capture,utilization and storage,CCUS)技术在油田的持续应用,CO_(2)腐蚀井下管柱现象引起高度重视,亟需适用于高CO_(2)分压环境下考虑腐蚀速率随时间变化影响的腐蚀速率模型。通过模拟温度80~120℃、CO...随着碳捕集、利用与封存(carbon capture,utilization and storage,CCUS)技术在油田的持续应用,CO_(2)腐蚀井下管柱现象引起高度重视,亟需适用于高CO_(2)分压环境下考虑腐蚀速率随时间变化影响的腐蚀速率模型。通过模拟温度80~120℃、CO_(2)分压15~30 MPa条件下Q125、3Cr和13Cr管材的腐蚀,建立了这3种管材考虑温度、CO_(2)分压和腐蚀时间影响的腐蚀速率预测模型,并对Q125套管进行了安全服役寿命预测。结果表明:同一CO_(2)分压下,Q125、3Cr管材腐蚀速率随温度增加呈先增后减的趋势,13Cr管材腐蚀速率随温度增加而增大;3种管材腐蚀速率均随CO_(2)分压增加而增大。Q125管材匀速和变速两种腐蚀速率模型均适用,3Cr和13Cr管材适用变速腐蚀模型。Q125套管的抗拉安全服役年限随着CO_(2)分压的增加而逐渐降低,抗拉安全服役年限最短约为12 a。展开更多
The strength-ductility trade-off in low-Mn lightweight steels is a significant challenge due to the low thermal stability of austenite and the presence ofδ-ferrite.Two types of low-Mn lightweight steels containing V ...The strength-ductility trade-off in low-Mn lightweight steels is a significant challenge due to the low thermal stability of austenite and the presence ofδ-ferrite.Two types of low-Mn lightweight steels containing V and NbVMo microalloying elements were developed by warm rolling.Among these,NbVMo steel demonstrated superior properties,achieving a tensile strength of~1.2 GPa and a product of strength and elongation exceeding 45 GPa%.In-depth mechanism analysis by atom probe tomography and quasi-in-situ electron backscatter diffraction revealed that different microalloying compositions influence the mechanical properties by strengtheningδ-ferrite,refining retained austenite and homogenizing matrix strain.In NbVMo steel,δ-ferrite strengthening is attributed to the synergistic effects of(V,Mo,Cr,Nb)C composite precipitation,fine NbC and MoC precipitates,and the solid solution strengthening of Mo.These mechanisms collectively contribute to a higher yield strength andδ-ferrite microhardness compared to V steel.Consequently,δ-ferrite and the surrounding matrix in NbVMo steel exhibit coordinated elongation during deformation,enhancing the ductility.The improved microstructural and strain uniformity in NbVMo steel mitigates stress concentration effects onδ-ferrite deformation and serves as a barrier that delays the transformation of retained austenite.In contrast,the retained austenite in V steel exhibits a blocky morphology with larger grain sizes,resulting in lower stability.Combined with localized stress concentrations due to non-uniform strain distribution,this leads to premature transformation of retained austenite to alleviate stress,ultimately impairing elongation and the continuity of strain hardening.Furthermore,the precipitation mechanisms of(V,Mo,Cr,Nb)C composite precipitates are elucidated.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.FRF-BD-25-001)Development and Application of Ultra-High Strength Hot Stamping Steel Strip for Automobiles(Grant No.20232BCJ22030)Manufacturing and Application Innovation and Integration of High-Safety Automotive Steel(Grant No.24431002D).
文摘The strength-ductility trade-off in low-Mn lightweight steels is a significant challenge due to the low thermal stability of austenite and the presence ofδ-ferrite.Two types of low-Mn lightweight steels containing V and NbVMo microalloying elements were developed by warm rolling.Among these,NbVMo steel demonstrated superior properties,achieving a tensile strength of~1.2 GPa and a product of strength and elongation exceeding 45 GPa%.In-depth mechanism analysis by atom probe tomography and quasi-in-situ electron backscatter diffraction revealed that different microalloying compositions influence the mechanical properties by strengtheningδ-ferrite,refining retained austenite and homogenizing matrix strain.In NbVMo steel,δ-ferrite strengthening is attributed to the synergistic effects of(V,Mo,Cr,Nb)C composite precipitation,fine NbC and MoC precipitates,and the solid solution strengthening of Mo.These mechanisms collectively contribute to a higher yield strength andδ-ferrite microhardness compared to V steel.Consequently,δ-ferrite and the surrounding matrix in NbVMo steel exhibit coordinated elongation during deformation,enhancing the ductility.The improved microstructural and strain uniformity in NbVMo steel mitigates stress concentration effects onδ-ferrite deformation and serves as a barrier that delays the transformation of retained austenite.In contrast,the retained austenite in V steel exhibits a blocky morphology with larger grain sizes,resulting in lower stability.Combined with localized stress concentrations due to non-uniform strain distribution,this leads to premature transformation of retained austenite to alleviate stress,ultimately impairing elongation and the continuity of strain hardening.Furthermore,the precipitation mechanisms of(V,Mo,Cr,Nb)C composite precipitates are elucidated.
