【摘要】 X80高钢级管线钢是我国长距油气输送管线的主要用材，应用过程中发现不同厂家钢板焊后焊缝金属韧性差异较大，严重影响油气储运安全。迫切需要一种能对沿焊缝厚度方向的元素分布进行快速、准确原位定量分析的方法，帮助探索X80管线钢母材与焊材的共同作用对焊缝金属韧性的影响机理。提出一种用LA-ICP-MS法对钢材焊缝中Mn元素、 Ni元素、 Cr元素、 Al元素及Nb元素进行原位定量分析的方法。通过优化激光脉冲频率20 Hz、激光能量100%（激光输出Imaged Aperture模式）、剥蚀孔径100μm及离焦距离0μm等提升质谱信号的强度及稳定性。实验采用基体匹配的标准样品进行校准，以基体元素⁵⁷Fe作为内标辅以校正。通过对相关质谱干扰进行分析，优选同位素²⁷Al、⁵³Cr、⁵⁵Mn、⁶⁰Ni及⁹³Nb。该方法线性相关系数达0.992 7～0.999 6,定量限0.23～2.57μg·g^-1。将建立的LA-ICP-MS微区原位定量分析方法应用于分析焊材相同而母材成分不同的2种X80管线钢焊缝中的元素含量分布。发现在两种母材中含量接近的Mn、 Cr、 Al、 Nb元素在焊缝根部表现的稀释情况相当，而在两种母材中含量差异较大的Ni元素在距焊缝根部8.4 mm以内的含量差异显著。冲击试验结果显示，母材中Ni元素含量高的焊缝韧性相对明显高。对焊缝根部进行SEM分析，发现Ni元素含量提高利于生成板条状贝氏体组织。分析结果表明，X80管线钢中加入0.14%的Ni元素可减少母材对根部焊缝金属中Ni元素的稀释作用，较高的Ni元素含量通过促进低温板条贝氏体相变而提高焊缝冲击韧性。所建立的LA-ICP-MS原位定量分析方法对保障X80长输管线的安全运行有借鉴意义。更多还原

【Abstract】 X80 high-grade pipeline steel is the main material used in long-distance oil and gas transmission pipelines. During the application process, it was found that there was a significant difference in the toughness of the weld metal after welding steel plates from different manufacturers, which seriously affected the safety of oil and gas storage and transportation. There was an urgent need for a fast and accurate in-situ quantitative analysis method for the distribution of elements along the thickness direction of the weld seam to help explore the mechanism of the joint effect of X80 pipeline steel base material and welding material on the toughness of the weld metal. Therefore, this article proposed a method for in-situ quantitative analysis of Mn, Ni, Cr, Al, and Nb in weld using LA-ICP-MS. By optimizing the laser pulse frequency to 20Hz, laser energy to 100%（laser output mode Image Aperture）, etching aperture to 100μm, and defocus distance 0μm, the strength and the stability of mass spectrometry signals were enhanced. The experiment was calibrated using standard samples matched with the matrix, and the matrix element⁵⁷Fe was used as the internal standard for correction. By analyzing related mass spectrometry interferences, isotopes²⁷Al, ⁵³Cr, ⁵⁵Mn, ⁶⁰Ni, and ⁹³Nb were selected. The established LA-ICP-MS micro zone in-situ quantitative analysis method was applied to analyze the distribution of element content in two X80 pipeline steel welds with the same welding material but different base material compositions. The correlation coefficient of this method ranged from 0.992 7 to 0.999 6, with a quantification limit of 0.23～2.57 μg·g^-1. The results showed that Mn, Cr, Al, and Nb with similar contents in the two base metals exhibited similar dilution at the root of the weld. In comparison, Ni elements with significant differences in content between the two base metals showed significant differences in content within 8.4 mm from the root of the weld. The impact test results showed that the toughness of weld with high Ni element content in the base material is relatively significantly higher. SEM analysis of weld root showed that the increase of Ni element content was conducive to forming lath bainite structure. Therefore, it is considered that the dilution of base metal to Ni in the root weld metal can be reduced by adding 0.14% Ni to X80 pipeline steel. The weld impact toughness can be improved by higher Ni content by promoting the low-temperature lath bainite transformation. The established LA-ICP-MS in-situ quantitative analysis method is of reference significance for ensuring the safe operation of the X80 long-distance pipeline.更多还原