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通过光学显微镜(OM)、透射电镜(TEM)观察及硬度、拉伸性能测试,研究了抗硫钻杆钢中析出相的析出行为。结果表明:抗硫钻杆钢中析出相的形貌及结构尺寸具有多重特征,表现出对回火温度的依赖性。580℃回火温度下,铁素体基体上析出微米量级的棒状及纳米量级的球形析出相,抗硫钻杆钢强度因而较高。回火温度升高到625℃,析出相形貌逐渐向球形演变,并且其体积分数增加,抗硫钻杆钢强度、塑性同时提高,强度达到150 ksi钢级,表现出良好的强度/韧性匹配。回火温度680℃下,析出相沿晶界析出并逐渐聚集,导致抗硫钻杆钢强度急剧降低。抗硫钻杆钢的强/韧性匹配依赖于析出相—位错交互作用和析出相—基体变形协调两种机制的相互竞争。
The precipitation behavior of the precipitated phase in the anti-sulfur drill stem steel was studied by optical microscope (OM), transmission electron microscope (TEM) observation and hardness and tensile test. The results show that the morphology and the size of the precipitated phase in the anti-sulfur drill stem steel have multiple features and show the dependence on the tempering temperature. 580 ℃ tempering temperature, the ferrite matrix precipitation of the rod-shaped and nano-scale particle size of the precipitated phase, anti-sulfur rod steel and thus higher strength. After the tempering temperature was raised to 625 ℃, the morphology of the precipitated phase gradually evolved into a spherical shape, and its volume fraction increased. Meanwhile, the strength and ductility of the anti-sulfur drill pipe steel increased at the same time and the strength reached 150 ksi steel grade, showing good strength / toughness matching . The tempering temperature of 680 ℃, the precipitated phase precipitates along the grain boundary and gradually gathered, resulting in a sharp decline in the intensity of anti-sulfur drill pipe steel. The strong / ductile matching of the anti-sulfur drill stem steel relies on the mutual competition of precipitation phase-dislocation interaction and precipitation phase-matrix deformation coordination.