【摘要】 为了研究双金属复合管中镍基合金堆焊层的耐腐蚀性能，分别采用钨极氩弧焊(GTAW)与冷金属过渡焊(CMT)两种焊接工艺在X65管线钢表面熔覆一层厚度为3 mm的625合金(Inconel625)内衬层．通过双环电化学动电位再活化(DL-EPR)试验来评估通过两种工艺得到的堆焊层的耐晶间腐蚀性能，试验得出通过CMT得到的堆焊层的晶间腐蚀敏感度(DOS)值比GTAW堆焊层的DOS值低0.5%，这表明相比于传统的GTAW堆焊层，通过CMT工艺得到的堆焊层具备更优良的耐晶间腐蚀性能．此外，模拟服役工况的失重腐蚀试验被用来进一步评估堆焊层的耐腐蚀性能，腐蚀试验后的GTAW堆焊层与CMT堆焊层试样表面均出现了不同程度的腐蚀，其中GTAW堆焊层试样表面出现了大量富含Fe、S的腐蚀产物，而CMT堆焊层表面仅存在极少量的腐蚀产物．通过腐蚀前后试样的质量变化计算得到GTAW堆焊层的腐蚀失重速率为0.12 mm/a，而CMT堆焊层其腐蚀失重速率仅为0.01 mm/a．这进一步证明了相比于GTAW工艺采用CMT工艺得到的堆焊层耐晶间腐蚀性能更好．此外，在同一焊接工艺下，堆焊层的耐晶间腐蚀性能存在不均性，靠近熔合界面位置处的堆焊层中较高的Fe含量降低了堆焊层的耐晶间腐蚀性能．更多还原

【Abstract】 To explore the corrosion resistance performance of the nickel-based alloy overlay applied to a bimetallic tube,gas tungsten arc welding(GTAW)and cold metal transfer(CMT)welding were used to deposit 625 alloy(Inconel 625)on X65 pipeline steel. The double-loop electrochemical potentiodynamic reactivation(DL-EPR) test was used to evaluate the intergranular corrosion resistance of the overlay. The DL-EPR test showed that the degree of sensitization(DOS)value of the CMT-welds was 0.5% less than that of the GTAW-welds,indicating that CMT-welds exhibited better resistance to intergranular corrosion. The weight-loss corrosion test under simulated service conditions showed the corrosion of the GTAW-welds and CMT-welds. Numerous corrosion products rich in Fe and S appeared on the GTAW-welds surface,while only a few existed on the CMT-welds surface. The corrosion rate of the GTAWwelds was calculated as 0.12 mm/a,while that of the CMT-welds was only 0.01 mm/a,further proving that compared to the GTAW-welds,the CMT-welds displayed better resistance to intergranular corrosion. In addition,under the same welding process,the intergranular corrosion resistance of the overlay was unevenly distributed,and the higher Fe content in the overlay near the X65 substrate reduced the intergranular corrosion resistance of the 625alloy overlays.更多还原