高钢级套管强韧性匹配研究

为了获得非常规油气资源开采所需的高强度、高韧性套管产品，以C-Mn 系中碳低合金热轧管坯为试验材料，通过930 ℃淬火+470～550 ℃系列温度回火热处理工艺研究了该套管管材的强韧性匹配规律。结果显示:随回火温度升高，管材强度呈下降趋势，冲击韧性先增后降。其原因在于随着回火温度升高，马氏体板条发生回复和再结晶，过饱和碳析出并形成弥散分布碳化物，导致管材强度降低且韧性升高；随着温度继续升高，碳化物发生偏聚和粗化，强化作用和晶界强度减弱，导致管材强度和韧性降低。研究表明，在930 ℃淬火/55 min+(510～530) ℃回火/110 min热处理工艺下，管材强韧性匹配最佳，屈服强度达到951 MPa以上，0 ℃下横向冲击功平均值达到98 J，完全满足Q/SY 07394标准对125 ksi 钢级高抗挤套管强韧性要求。

Study on Strength and Toughness Matching of High Grade Casing

In order to obtain high strength and toughness casing products needed for unconventional oil and gas resources exploitation,the matching law of strength and toughness of C-Mn medium carbon low alloy hot rolled tube was studied by 930 ℃quenching +470～550 ℃series temperature tempering heat treatment process.The results show that with the increase of tempering temperature,the strength of pipe decreases,while the impact toughness increases first and then decreases.The reason is that with the increase of tempering temperature, martensitic slat recovers and recrystallizes, supersaturated carbon precipitates and forms dispersed carbides, which leads to the decrease of strength and increase of toughness of pipe. As the temperature continues to rise, the carbide segregation and coarsening occur, and the strengthening effect and grain boundary strength weaken, resulting in the decrease of the strength and toughness of the pipe. The results indicate that under the heat treatment process of 930 ℃quenching /55 min+(510～530) ℃tempering /110 min, the pipe has the best matching of strength and toughness, the yield strength reaches 951 MPa and the average transverse impact energy reaches 98 J at 0 ℃, fully meeting the strength and toughness requirements of 125 ksi steel grade high anti-collapse casing in Q/SY 07394 standard.