Deng Xuyan,Wang Juchao,Zhang Lingtong,et al.Effect of Nonmetallic Inclusion on Impact Toughness of High Strength Oil Casing[J].Special Steel,2026,47(03):137-142.
Deng Xuyan,Wang Juchao,Zhang Lingtong,et al.Effect of Nonmetallic Inclusion on Impact Toughness of High Strength Oil Casing[J].Special Steel,2026,47(03):137-142. DOI: 10.20057/j.1003-8620.N250523.
The number, size, chemical composition and morphology of inclusions in continuous casting billet samples were analyzed using SEM and bulk sample electrolysis for high strength OCTG steel. The results show that the micro inclusions and large inclusions in the continuous casting billets are significantly higher than the stable casting state in the biginning casting stage of the tundish.T.O content in the billet is less than 10×10
-6
, and the macro inclusion content in the billet is less than 1.5 mg/10 kg in the stable casting stage. The seamless steel pipes produced from round billets at casting start stage exhibit significant fluctuations in impact energy, with the maximum impact energy being 1.4 times the minimum. The impact energy decreases as the T.O content in the steel increases.Samples with lower impact energy show a higher area fraction of inclusions, the inclusion area fraction in the 37 J sample is 2.1 times that of the 53 J sample. Nonmetallic inclusions in the steel are the primary cause of the impact energy fluctuations.
Wang Y K , Kang J , Liu D S , et al . Effect of V and Nb on the microstructure and properties of high strength and toughness steel for petroleum casing [J]. Journal of Materials Research and Technology , 2024 , 29 : 1403 - 1413 .
Huang Y , Cheng G G , Li S J , et al . Effect of Ti(C, N) particle on the impact toughness of B-microalloyed steel [J]. Metals , 2018 , 8 ( 11 ): 868 .