渡辺(2309)_渡辺(2309)

[ 29 p. 241-247 (2011)] ** *** ** ** Development of a nickel-based filler metal containing a small amount of silicon by WATANABE Takehiko, WAKATSUKI Ken, YANAGISAWA Atsusi and SASAKI Tomohiro Authors tried to develop a new nickel-based brazing filler metal containing no boron and phosphorous to suppress the formation of brittle phases in a brazed layer. The properties of a joint brazed using the new filler metal were investigated and compared with those of a brazed joint using a conventional nickel-based filler metal of BNi-5. The following results were obtained in this study. A new nickel-based brazing filler metal was successfully developed, which contains a small amount of Si and Mn and shows the melting temperature lower than about 1090. The hardness of the new filler metal was about 40% that of BNi-5 filler metal containing about 10% Si. In brazing of SUS304 stainless steel, using BNi-5 filler metal, a hard and brittle finally-solidified region appeared in the brazed layers with joint clearance over 100 m. However, using the new filler metal, the finally-solidified region appeared in the brazed layers with joint clearance over 200 m. The hardness of the finally-solidified region in the brazed layer using the new filler metal was about 54% that using BNi-5 filler metal. The tensile strength of a SUS304 joint brazed using BNi-5 filler metal extremely decreased at joint clearance over 100 m. On the other hand, the tensile strength of a joint brazed using the new filler metal decreased at joint clearance over 200 m. It seems that the brittle finallysolidified region formed in a brazed layer causes the joint to decrease the tensile strength. It was shown that the newly developed filler metal is superior to the conventional BNi-5 filler metal in hardness and in tensile strength of joints with wider joint clearance. Key Words: Brazing, Ni-based filler metal, Ni-Cr-Mn-Si alloy system, Joint tensile strength, BNi-5 filler metal, Brittle finally-solidified region 1. 2. B P Si 50 m 1) B P Si * 23 3 1523 9 30 ** Member, Niigata University, Graduate School of Science and Technology *** Member, Daido Steel Co. Ltd. B P Si Ni 33Cu 15Sn 2Si Ni 55Cu 18Mn 1.5Si 2) SUS316 100 m JIS BNi 2 BNi 5 50 m Cu 1 1100 2 B P Si 3 Thermo-Calc KP Ni Ni Cr 3) Ni

242 Mn 3) Ni Fe 8 10 mass% Si 3) Ni Cr Mn Si 3. Ni Cr Mn Si Thermo-Calc Cr 20mass% Si 4 5, 6 mass% Mn Fig. 1 (a), (b) (c) 1000 (b) 5 mass%si 990 Mn Si 5 mass% Mn 7 mass% 10 mass% Cr Fig. 2 (a) (b) Fig. 2 (b) Ni 31%Cr 10%Mn 5%Si (mass%) 995 Fig. 1 (c) 6 mass%si 990 Mn 4 mass% Cr Fig. 2 (c) 980 4. 1000 Ni Cr Mn Si 6 Table 1 Mn Si 99.9% Ni, Cr, Mn, Si 20 g Table 1 6 EPMA Table 1 0.5 1 mass% 4.1 6 DTA Table 1 60 100 1100 Ni 30Cr 4Mn 6Si 980 1110 JIS BNi 5 Fig. 1 Calculated phase diagrams of Ni-20Cr-Mn-Si system when Si and Mn contents were changed. Fig. 2 Calculated phase diagrams of Ni-Cr-Mn-5Si or -6Si system when Cr and Mn contents were changed.

29 2011 4 243 Table 1 Compositions of six kinds of candidates for filler metal and their calculated liquidus, measured solidus and liquidus. Fig. 3 Solidified microstructures of filler metal candidates with various amounts of Mn and Si. Table 1 4.2 Fig. 3 (a) (f) 6 10Mn5Si EPMA 50.0at%Ni 35.5at%Cr 7.0at%Mn 7.5at%Si Ni Cr Mn Si Ni 47.5at%Ni 15.8at% Cr 17.7at%Mn 19.0at%Si Ni Cr Si 4 5) Ni 13 Cr 6 Si 7 Cr Mn Ni 13 (Cr, Mn) 6 Si 7 Fig. 3 (g) 1Mn5Si Mn Si Si 5 mass% Mn Ni 31%Cr 1%Mn 5%Si (mass%) (1Mn5Si) 21Mn5Si 10Mn5Si 7Mn5Si Fig. 3 (g) 1Mn5Si Fig. 3 (b) (c) (d) 7Mn5Si 10Mn5Si 21Mn5Si Mn Fig. 4 Area ratio of finally solidified region in microstructure of filler metal candidates with various amounts of Mn and Si. Fig. 4 Si 54%Ni (36 x) %Cr 10%Mn x%si (mass%) x 1, 3, 8 10Mn5Si Fig. 5 Si Fig. 6

244 Fig. 5 Solidified microstructures of filler metal candidates with various amounts of Si and constant amounts of 10% Mn. Fig. 6 Area ratio of finally solidified region in microstructure of filler metal candidates with various amounts of Si and constant amounts of 10% Mn. 4.903 N 0.981 N 15 s Fig. 7 BNi 5 Mn Mn Si Mn 7Mn5Si 10Mn5Si 5. 10Mn5Si 10Mn5Si BNi 5 5.1 Fig. 7 Mn content and Vickers hardness of primary crystal and finally solidified region of filler metal candidates and mean hardness, including the hardness of BNi-5. Ni Cr Mn Si Mn Si 4.3 Ni 19mass%Cr 10mass%Si BNi 5 630 HV 6mm SUS304 45 mm 800 4mm 10Mn5Si 50 m 100 m 200 m 400 m 50 m 100 m 200 m 400 m BNi 5 1 10 2 Pa 0.04 MPa 4 /s BNi 5 10Mn5Si 1170 600 s 4mm 20 mm

29 2011 4 245 0.5 mm/min 5.2 100 m Fig. 8 Fig. 8 (a) (b) BNi 5 10Mn5Si BNi 5 10Mn5Si BNi 5 10Mn5Si EPMA Table 2 Table 1 BNi 5 19mass% Cr 10mass%Si BNi 5 Si Si Cr 10Mn5Si Mn 6) Fe SUS304 200 m Fig. 9 Fig. 9 (a) (b) BNi 5 (c) 10Mn5Si BNi 5 100 m (b) 10Mn5Si 100 m EPMA Table 3 BNi 5 Si 10Mn5Si Mn Si BNI 5 Fe 10Mn5Si Fe BNi 5 BNi 5 250 HV 740 HV 10Mn5Si 200 HV 200 m 400 HV BNi 5 Table 2 Chemical compositions of primary crystal and finally solidified region in brazed layers with 100 m joint clearance, using BNi- 5 and 10Mn5Si filler metals. Table 3 Chemical compositions of primary crystal and finally solidified region in brazed layers with 200 joint clearance, using BNi-5 and 10Mn5Si filler metals. Fig. 8 Microstructures of brazed layers with 100 m joint clearance, using BNi-5 (a) and 10Mn5Si (b). Fig. 9 Microstructures of brazed layers with 200 m joint clearance, using BNi-5 (a), (b) and 10Mn5Si (b). Crack is observed along a finally solidified region in the brazed layer of (b).

246 Table 3 Si Ni Si 3) Ni Cr Si 4) Ni 2 Si Ni Cr (Ni, Cr) 2 Si Fig. 9 (b) BNi 5 100 m 5.3 50 m 400 m Fig. 10 BNi 5 100 m 170 MPa 10Mn5Si 50 m 100 m 500 MPa 200 m 270 MPa SUS304 580 MPa Fig. 11 BNi 5 100 m Fig. 11 (a) 10Mn5Si 200 m Fig. 11 (b) Fig. 10 BNi 5 10Mn5Si 100 m 200 m 6. Fig. 10 Fig. 11 Tensile strength of joints brazed using BNi-5 and 10Mn5Si with various joint clearance. Fracture paths occurred along a finally solidified region in a brazed layer. (a): BNi-5, 100 m joint clearance (b): 10Mn5Si, 200 m joint clearance B P BNi 5 1 Si Mn 1090 Ni Cr Mn Si Si 10mass% BNi 5 40% 2 SUS304 BNi 5 100 m 200 m BNi 5 54% 3 SUS304 BNi 5 100 m 170 MPa 200 m 270 MPa 4BNi 5

29 2011 4 247 1) Welding handbook 8th Edition, AWS, Vol.2 (1991), 402. 2) S. Saito, T. Kayamoto and T. Onzawa: Mechanical properties of stainless steel joint brazed with Ni-Cu based filler metals, Quarterly J. of Japan Welding Society, 17-1 (1999), 35-40. (in Japanese) 3) Edited by T. B. Masalski et al: Binary Phase Diagrams on CD- ROM, ASM, (1996). 4) Handbook of Ternary Alloy Phase Diagrams, ASM International, (1995). 5) K. Sasabe:, Japan Welding Engineering Society, No.9 (1992), 17. (in Japanese) 6) Edited by Japan Institute of Metals: Metal Data Book, Maruzen, (1974), 73. (in Japanese)