Abstract: The production process of tested 12MnNiVR pressure vessel steel plate (/% : ≤0.15C, 0.15~0.40Si, 1.20~1.60Mn, ≤0.008P, ≤0.018S, 0.15~0.40Ni, ≤0.30Cu, 0.02~0.06V) is KR metal desulphurization- 90t BOF- RH- 210~300mm slab casting-rolling to 20~30mm steel plate. The liquid total oxygen content, inclusions number, inclusion size distribution, morphology and ingredient of unqualified specimen of 12MnNiVR pressure vessel steel plate in RH refining and casting process have been studied by scanning electron microscope. Results show that the linear Al₂O₃ defect formed by rolling is main reason of un-qualification of plate by nondestructive test; with process measures including controlling BOF tapping temperature 1650℃ , liquid temperature before RH refining ≥l610℃ , decreasing oxygen blowing amount in RH refining process, strengthening shielding process and RH cycling time ≥10min, the qualified rate of pressure vessel steel plate by nondestructive test increases from original 96.85% to 99.07%.

Key words: 12MnNiVR Pressure Vessel Steel Plate, Unqualified Plate by Nondestructive Test, Al₂O₃ Inclusion, RH Refining, Shielding Casting

摘要： 试验12MnNiVR压力容器钢板（/%:≤0.15C，0.15~0.40Si，1.20~1.60Mo，≤0.008P，≤0.018S，0.15~0.40Ni，≤0.30Cu，0.02~0.06V）的生产工艺为KR铁水脱硫-90t BOF-RH-210~300mm板坯连铸-轧制成20~30mm钢板，用扫描电镜分析了容器钢板，研究12MnNiVR容器钢RH精炼和连铸过程钢液全氧含量、夹杂物数量、粒径分布、形貌和组成。结果表明，Al₂O₃夹杂物经轧制发展形成线状缺陷是钢板探伤不合格主要原因；RH精炼过程钢水偏低，吹氧量高和连铸过程钢液二次氧化易造成Al₂O₃夹杂物超标；通过控制BOF出钢温度1650℃,RH前钢水温度≥1610℃，减少RH精炼过程升温吹氧量，RH循环时间≥10min，加强保护浇铸等工艺措施，容器钢板探伤合格率由96.85%提高到99.07%。

关键词: 12MnNiVR容器钢板, 探伤不合格, Al₂O₃夹杂, RH精炼, 保护浇铸