目的 研究X70管线钢在高温高压CO2饱和溶液中不同流速下的冲刷腐蚀行为。方法 通过流体动力学模拟的方法，获得不同喷射流速下壁面切应力的变化规律。采用喷射冲击试验装置，利用扫描电镜、表面形貌测试仪、维氏硬度仪等设备和失重测量方法，分析喷射速度对X70管线钢CO2冲刷腐蚀行为的影响。结果 随着喷射流速Uexit的增大，试样表面的壁面切应力和壁面压应力逐渐增大。随距喷射中心距离(径向距离)的增大，壁面切应力先增大后减小，壁面压应力急剧减小。在低流速(Uexit≤10 m/s)情况下，最大壁面切应力所对应的特征攻角大约为23°;当流速Uexit≥20 m/s时，特征攻角迅速增至45°左右，且变化很小。试样表面形貌表现出明显的三个区域:停滞区、过渡区、壁面喷射区，且在低流速下，三个区域划分更为明显。在20 m/s喷射速度下，壁面切应力呈现中心轴对称变化，为“M”形状，试样表面的冲蚀轮廓(冲蚀深度)呈现中心对称的“W”形状变化，大约在距中心滞点4 mm左右，即最大壁面切应力附近出现最大冲蚀深度，约55 μm。试样表面硬度随径向距离的增大而减小，中心停滞区硬度高达340HV10。喷射流速从10 m/s增加到40 m/s时，冲蚀速率由11.86 mm/a增加到32.97 mm/a。结论 X70管线钢的典型形貌特征与喷射流体的壁面切应力大小和CO2腐蚀有关，最大壁面切应力处产生的冲蚀最为严重，冲蚀速率(Rcorr)与喷射流体的流速呈现线性关系，即Rcorr=4.861+0.714×Uexit。

The work aims to study the erosion-corrosion behavior of pipeline steel X70 at different velocity in high- temperature and high-pressure CO2 saturated environment. The change trend of wall shear stress under different jet velocity was obtained by computational fluid dynamic (CFD) method, and a jet impingement simulating flow loop was used to study the influence of jet velocity on the CO2 erosion-corrosion of pipeline steel X70 through scanning electron microscopy (SEM), surface morphology profile apparatus, Vickers micro-hardness tester and metal loss measurement. The wall shear stress and compressive stress of the sample increased gradually as the jet velocity Uexit increased. With the increase of the distance to the jet center (radial distance), the wall shear stress increased firstly and then decreased and the wall compressive stress rapidly decreased. At a low velocity (Uexit≤10 m/s), the characteristic impingement angle was approximately 23° at the maximum wall shear stress location, but the characteristic impingement angle increased rapidly to 45° and then changed mildly at high velocity (Uexit≥20 m/s). The macroscopic morphology of samples showed obvious three regions:stagnation region, transition region and wall jet region, and the region distribution was more obvious at low velocity. At a jet velocity of 20 m/s, the wall shear stress presented the axial symmetry shape of “M” based on the sample center, and the erosion contour (depth of erosion-corrosion) of the sample surface presented a symmetrical shape of “W”. The maximum depth of erosion-corrosion was about 55 μm and appeared near the maximum wall shear stress, about 4 mm far from the stagnation region of sample center. The surface hardness of sample decreased with the increase of radial distance, and the hardness in the central stagnation region was up to 340HV10. When the jet velocity increased from 10 m/s to 40 m/s, the erosion-corrosion rate increased from 11.856 mm/a to 32.969 mm/a. The typical morphology of X70 pipeline steel is related with value of wall shear stress and influence of CO2 corrosion, and the erosion-corrosion is most serious at the location of maximum wall shear stress. The erosion-corrosion rate is regarded to be directly proportional linear to the velocity, Rcorr=4.861+0.714×Uexit.