回火温度对超高强高韧V150套管组织性能的影响

采用力学性能测试、金相组织观察、透射电镜以及扫描电镜观察,研究不同回火温度对超深井用超高强高韧套管组织和力学性能的影响规律。研究结果表明:套管经580～700℃回火的组织均为回火索氏体,在580～630℃回火时组织比较稳定,仍然保持着淬火马氏体的位向和形状,在640℃回火时发生铁素体再结晶,在700℃回火时发生组织粗化;与热轧态相比,淬火回火后的塑性和韧性得到了很大提高,在580～700℃回火,未出现第二类回火脆性;随着回火温度的升高,套管的强度和硬度逐渐降低,塑性和韧性逐渐增加;650℃为套管最佳回火温度,回火组织均匀,铁素体再结晶充分,碳化物细小弥散分布,强度达到V150钢级,0℃时横向冲击功接近110 J,强韧性匹配达到最佳。

Effects of tempering temperature on microstructures and properties of V150 casing and tubing with ultra-high strength and toughness

Effects of tempering temperature on microstructures and properties of casing tube with ultra-high strength and good toughness were studied by OM,TEM,SEM and mechanical property tests.The results show that complete tempered-sorbite microstructure can be obtained tempered at 580-700 ℃.After tempering at 580-630 ℃,the microstructure still keeps the exposure and shape of martensite,which demonstrates that the microstructure is of certain stability.Ferrite recrystallization occurs at 640 ℃ and the microstructure begins to coarsen when the tempering temperature is up to 700 ℃.Compared with the hot rolled steel,the ductility and toughness of the steel after quenching and tempering are improved greatly.High temperature tempering embrittlement is not found at 580-700 ℃,and the strength and hardness decrease gradually with the increase of ductility and toughness at elevated tempering temperature.When tempering at 650 ℃,the optimum matching between strength and toughness can be realized,fine microstructures can be gotten,which satisfies the requirement of V150 well tube steel,and therefore,the optimum tempering temperature is 650 ℃.