125ksi超级马氏体油管成分-组织-性能-工艺综合控制技术

Composition-Structure-Properties and Process Comprehensive Control Technology of 125ksi Super Martensitic Oil Well Pipe Material

125ksi钢级15Cr超级马氏体不锈钢具有优良的高强度、高韧性匹配与耐CO_2腐蚀性能,是深度>7000 m深井油井管的候选材料。从成分设计、生产工艺、组织调控等方面,论述了15Cr超级马氏体不锈钢油管的高强高韧综合控制技术。成分控制方面,采用无δ铁素体成分设计,w[Cr]取15%,w[Ni]取6.5%~7%,w[C]取0.01%~0.03%,w[Cu]取1.25%~1.5%,Cr、Ni元素合理匹配是降低δ铁素体含量的主要因素,C、Cu含量的合理匹配是获得高强高韧力学性能的关键因素。冶炼工艺方面,研究了电弧炉钢杂质元素的影响,结果表明,V、N、Al杂质元素会增加15Cr钢的硬度,将回火温度提高至550~575℃,能够降低硬度保证韧性。热加工成型方面,通过热变形试验,获得了15Cr钢的动态再结晶规律,制定了无缝管热穿孔成型变形温度1100~1150℃,能够获得细小的再结晶晶粒。组织性能调控方面,通过热处理工艺研究,确定了正火温度采用950~980℃,即能保证晶粒尺寸不明显长大,又能获得高强度与高韧性的匹配。

The 125ksi grade 15Cr super martensite stainless steel exhibits excellent high strength and high toughness matching,and corrosion resistance to CO2,which making it a promising material for oil well pipes exceeding a depth of 7000 m.This paper comprehensively discusses the control technology for achieving high strength and high toughness in 15Cr super martensite stainless steel tubing through composition design,production process optimization,and microstructure regulation.In terms of composition control,aδferrite-free composition design is employed with a chromium content(w[Cr])of 15%,nickel content(w[Ni])ranging from 6.5%to 7%,carbon content(w[C])between 0.01%and 0.03%,and copper content(w[Cu])varying from 1.25%to 1.5%.The appropriate combination of chromium and nickel elements plays a crucial role in reducing theδferrite content,while the optimal balance between carbon and copper contents is key to obtaining superior mechanical properties characterized by high strength and high toughness.Regarding the smelting process,this study investigates the influence of impurity elements on electric furnace steel.The results show that vanadium(V),nitrogen(N),and aluminum(Al)impurities increase the hardness of the 15Cr steel alloy.and raise the tempering temperature to 550℃-575℃,which can reduce the hardness and ensure the toughness.Concerning hot processing and molding techniques,the dynamic recrystallization behavior are obtained through hot deformation tests conducted on the15Cr steel alloy.The optimum hot perforation deformation temperature for seamless pipe manufacturing falls within 1100℃ to 1150℃ as it facilitates grain refinement via fine recrystallized grains formation.Microstructure regulation involves determining an appropriate normalizing temperature during heat treatment processes.The research results suggest that normalizing at temperatures ranging from 950℃ to 980℃ helps maintain grain size without significantly grown,while the match of high strength and high toughness can be obtained.