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59 NACE INTERNATIONAL: VOL. 56, NO. 3 MATERIALS PERFORMANCE MARCH 2017 the formation of carbides and intermetallic compounds, thus reducing the risks of chromium depletion. 5 In other research, the influence of filler metals on the microstructure, mechanical properties, and corrosion behavior of AISI Type 316L (UNS S31603) welds was investi- gated using two different fillers (ER2553 and ERNiCr -3). It was concluded that ER2553 exhibited better mechanical and corrosion properties and could be adopted to achieve optimal properties compared to over-alloyed filler. 6 Experimental Procedure In this study, three filler metals (ER316L, ERNiCrMo-3, and ERNiCu-7) were used to investigate the effect of alloy elements on corrosion behavior. The compositions of these filler metals are shown in Table 1. The base metal used in the investigation was Type 316L SS. The welding parameters and welding processes are listed in Table 2. Results and Discussion Corrosion Test C-ring samples corresponding to ASTM G58 7 were used to perform the SCC testing in sulfuric acid (H 2 SO 4 ) (0.82 kmol/m 3 ) at 40 °C and pH 0.6. The corrosion testing was conducted in a water bath with a temperature accuracy of ±1 °C. After 30 days, the corrosion sam- ples were inspected. Corrosion of the sam- ples is shown in Figure 1, and analyses of the precipitation microstructures of the corroded test samples by scanning electron microscopy (SEM) are shown in Figures 2 and 3. Figure 1 shows corrosion of the sam- ples after 30 days. Corrosion can be seen in the ERNiCu-7 (Sample 3) weld area and in the heat-affected zone (HAZ) of ER316L SS (Sample 1). Scanning Electron Microscopy Evaluation For all samples, microstructure and point analysis in the weld metal zone were inspected. In the ER316L SS weld region, Figure 2 shows that Cr 3 C 2 precipitated at the grain boundaries, which can deplete chromium from the grains and result in a decrease in the corrosion resistance of the weld area. TABLE 1. CHEMICAL COMPOSITIONS OF THE DIFFERENT FILLER METALS (WT%) Elements Filler Metals C Si Mn S Cr Cu Fe Ni Mo Nb Ti ER316L 0.01 0.53 1.7 0.007 23.91 0.27 58.48 12.8 1.71 0.006 ERNiCrMo-3 0.1 0.5 0.5 0.015 23.00 0.5 5.00 60 10.0 4.50 0.4 ERNiCu-7 0.15 1.00 4.0 0.015 28.0 2.50 62.0 2.5 3.2 TABLE 2. WELDING PARAMETERS Sample No. Welding Process Filler Metal Current (A) Polarity Average Weld Rate (mm/min) Heat Input (j/mm) 1 TIG (A) ER316L 165 DCEP (B) 80 2,725/5 2 TIG ERNiCrMo3 165 DCEP 80 2,725/5 3 TIG ERNiCu7 165 DCEP 80 2,725/5 (A) Tungsten inert gas. (B) Direct current electrode positive. FIGURE 1 Corrosion of the three samples after 30 days.