表面感应加热淬火抽油杆残余应力衰减的研究

Investigation in attenuation of residual stress on surface induction hardened sucker rods

为提高抽油杆的疲劳极限，研究了经表面感应加热淬火的抽油杆在疲劳极限应力作用下残余应力的衰减规律。结果表明，残余应力的衰减主要取决于心部组织的静屈服强度和循环屈服特性。心部组织静屈服强度高，又具有循环硬化特性的，残余应力衰减量小。反之，衰减量大。但是，残余应力的衰减主要发生在前几百个循环周次内，当循环周次超过１００次，不管心部材料是循环硬化的还是循环软化的，残余应力的衰减量都很小。由此，结合采用喷丸工艺，研制出疲劳极限达到６７０ＭＰａ的超高强度抽油杆，大大超过美国ＥＬ级抽油杆（５５４ＭＰａ）的水平。

To improve the fatigue limit of sucker rods,the attenuation pattern of the residual stress of surface induction hardened sucker rods under the action of fatigue limit stress is investigated.The result shows that the attenuation of the residual stress depends mainly on the static yield strength and cyclic yield characteristic of the core microstructure;it is slight when the sucker rod core provides higher static yield strength and cyclic hardening characteristic;and,taken altogether,it occurs principally in the first several hundreds of cycles and becomes insignificant in over 1000 cycles.Based on these,and combined with the use of shot-peening,exact-high strength sucker rods with a fatigue limit of 670MPa are developed.