Inconel625合金及焊缝在Na_(2)SO_(4)-NaCl熔盐中热腐蚀行为  

Hot Corrosion Behavior of Inconel625 Alloy and Welds in Na_(2)SO_(4)-NaCl Molten Salt

作　　者：张忠科[1,2] 熊健强 初树晟 李轩柏 蒋常铭 Zhang Zhongke;Xiong Jianqiang;Chu Shusheng;Li Xuanbai;Jiang Changming(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《稀有金属材料与工程》2023年第5期1842-1850,共9页Rare Metal Materials and Engineering

基　　金：甘肃省科技重大专项(18ZD2GC013)。

摘　　要：对Inconel625母材与焊缝金属进行750℃下的75%Na_(2)SO_(4)-25%NaCl混合熔盐热腐蚀实验,并对腐蚀产物的物相、表面形貌、腐蚀失重速率及腐蚀机理等进行分析。结果表明:Inconel625接头母材处组织为奥氏体等轴晶,焊缝处组织为树枝晶;母材与焊缝金属失重曲线均遵循抛物线规律,其失重速率常数分别为3.43和4.18 mg^(2)·cm^(-4)·h^(-1);焊缝金属因为富Nb第二相的析出,导致其与母材相比耐蚀性较差,腐蚀表现出“不均匀性”;2种状态下的Inconel625有着相同的腐蚀层结构均为:外层NiO颗粒和片层状NiCr_(2)O_(4),中层致密Cr2O3氧化层,内层“蜂窝”状Ni_(2)S_(3)硫化层的3层结构。Inconel625合金在750℃下75%Na_(2)SO_(4)-25%NaCl混合盐中的主要腐蚀机理为“硫化-氧化”腐蚀。Inconel625 base metal and weld metal were subjected to 75%Na_(2)SO_(4)-25%NaCl mixed molten salt for hot corrosion experiments at 750℃.The phase,surface morphology,corrosion mass loss rate and corrosion mechanism of corrosion products were studied.The results show that the microstructure of Inconel625 joints is austenitic equiaxial crystal at the base material and dendrite at the weld.The mass loss curves of both base metal and weld metal follow parabolic laws with mass loss rate constants of 3.43 and 4.18 mg 2·cm-4·h-1,respectively.The weld metal is less resistant to corrosion compared to the base material due to the precipitation of Nb-rich second phase,and there is corrosion“inhomogeneity”.Inconel625 in both states has the same corrosion layer structure i.e.the outer layer of NiO particles and lamellar NiCr_(2)O_(4),the middle layer of dense Cr2O3 oxide layer,and the inner layer of“honeycomb”Ni_(2)S_(3) sulfide layer with three-layer.The main corrosion mechanism of Inconel625 alloy in 75%Na_(2)SO_(4)-25%NaCl mixed salt at 750℃is“sulfidation-oxidation”corrosion.

关 键 词：INCONEL625合金 等离子焊接 混合熔盐 腐蚀机制 硫化-氧化 

分 类 号：TG146.15[一般工业技术—材料科学与工程] TG171[金属学及工艺—金属材料]