小直径薄壁钢管HIC腐蚀评价方法探讨

Discussion on the Evaluation Method of HIC Corrosion of Thin-Walled Steel Tubes with Small Diameters

对管线钢10(HSC)在NACE A溶液中进行氢致开裂试验,通过形貌观察、裂纹统计与评价等方法研究了试样形式、裂纹测量和氢致开裂(HIC)裂纹认定对小直径薄壁管线钢氢致开裂性能的影响。结果表明:舟形或整管试样应以中性层的弧长和试样的壁厚作为试样裂纹率的计算依据;钢管中的HIC裂纹可能呈现为不规则状,平行于试样中性层的方向为裂纹的长度方向,垂直于试样中性层的方向为裂纹的厚度方向;小直径薄壁管对裂纹厚度率非常敏感,相关标准中"位于内壁或外壁1 mm以内的裂纹不算作HIC裂纹"的规定不适用于小直径薄壁管,对于小直径薄壁管的HIC腐蚀应建立新的评价方法。

10(HSC)steel pipe was taken as the research object for hydrogen-induced cracking(HIC)test in NACE A solution.The influence of sample preparation,crack measurement and result statistics on the HIC performance of small-diameter thin-walled steel pipes was studied by the means of morphology observation,and crack statistics and evaluation.Results showed that the arc length of the neutral layer and the wall thickness of the pipe should be taken as the basis for calculating the crack ratio of the boat-shape sample or the whole pipe sample.The HIC cracks in the steel tube might appear irregular.In addition,the direction parallel to the neutral layer of the sample was the length direction of the cracks,while the direction perpendicular to the neutral layer of the sample was the thickness direction of the cracks.The small-diameter thin-walled tube was very sensitive to the crack thickness rate,and the previous standard that the cracks within 1 mm of the inner wall or the outer wall were not considered as HIC cracks was not suitable for small-diameter thin-walled tube,and new evaluation method should be established for the HIC corrosion on thin-walled tubes with small diameters.