-25-

The Effect of Cooling Rate and Filler Metal on the Properties of Vacuum

Brazed Joint for 2205 Duplex Stainless Steel

Liu-Ho Chiu*, Yi-Chun Ling*, Chia-Hsun Chang*, Wen-Chin Hsieh*

0.85 /s 0.1 /s 0.067 /s UNS31803(2205)

BNi-3 BNi-7

0.067 /s Avesta

2205 GMTC 2205 12.1 17.5 BNi-3 BNi-7 Cu

2205 110~135MPa 50~80MPa 220~250MPa

(0.85 /s)

2205

AbstractThe influence of cooling rates and types of filler on the mechanical properties and corrosion resistance

of the vacuum brazed joints for two 2205 duplex stainless steels was investigated. From the experimental

results, the precipitation of phase was obviously inhibited at a cooling rate of 0.85 /s. The amount of

phase precipitated was increased as the cooling rate was lowered. The shear strengths of vacuum brazed

joints were obtained in the range of 50-80 MPa, 110-135 MPa and 220-250 MPa for using BNi-7, BNi-3

and copper foil as filler, respectively. When the amount of phase was increased, the weight lost of

corroded specimen was increased rapidly. The galvanic corrosion behavior was observed in three brazed

joints using different filler in the chloride solution.

Keywords 2205 duplex stainless steel, vacuum brazed joint, corrosion, phase.

*

Department of Materials Engineering, Tatung University

25 34 89 12

Journal of Chinese Corrosion Engineering, Vol.14 No.4, PP.25~34(2000)

-26-

89 12

(1-3)

316

SMAW GTAW TIG

(3-5)

Potgieter (6) SAF2205

10%H2SO

43.5%NaCl

Wilms (7) Cr Mo

(8 9)

(11)

(GMTC) 65mm

2205 Avesta 2mm

2205 1

2205 55mm 15mm 2mm

Wall Colmonoy BNi-

3 BNi-7 2

10-5

Torr 10-3

Torr

2205 55mm 15mm

2mm 0.02mm

Nicrobraze S-Binder

1

BNi-3 BNi-7 1020 1090

10 0.85 /s( 10-3Torr) 0.1 /s

10-5Torr 0.067 /s 10-5Torr

6mm/min

2205

10wt H2C

2O

4

2H2O 1A/cm2

-27-

2205

40 OM

Groesbeck etching solution 4gNaOH

4gKMnO4

100gH2O

90 150

OM

GMTC 2205 Avesta 2205

ASTM G48 (10)

20mm 15mm 2mm 15mm 10mm

4mm 5min

6 FeCl3

2205

Critical Pitting

Temperatures CPT 47.5

47.5 24

15min

2 2205

2205

65mm Avesta 2205

2205 50

30~50 m Avesta 2205

50

10~20 m

2205 1050

0.85 /s( 10-3Torr) 0.1

/s 10-5Torr 0.067 /s 10-5Torr

2(a)~(c)

GMTC 2205

0.85 /s 0.1 /s 0.067 /s

0.85 /s

(Step Structure)

0.1 /s

(Dual Structure)

0.067 /s

GMTC 2205

2205

(8)

4-(a)~(c) Avesta 2205

1050 10 0.85 /s 0.1 /s

0.067 /s

Avesta 2205

2205 0.1 /s 0.067 /s

(8) 2205 / /

0.1 /s 0.067 /s

(11) 2205

1020~1080 0.25

/s

5(a)~(c) GMTC 2205

Groesbeck solution

Groesbeck solution

0 7.8 17.5

GMTC 2205

-28-

89 12

Avesta 2205 1050

10 0.1 /s 0.067 /s

Groesbeck

2.9 12.1

GMTC 2205

GMTC 2205 Avesta

2205 Mo GMTC 2205

Avesta 2205 GMTC 2205

GMTC 2205 Avesta 2205

single lap

2205 1020 1080 (8)

1020

1080

2205 0.85 /s

0.1 /s 0.067 /s

3 3 BNi-3

110~135MPa BNi-7

50~80MPa

Cu foil

220~250MPa (12) 304

3

Avesta 2205 BNi-3 BNi-7

0.85 /s 0.1 /s

0.067 /s

0.85

/s

BNi-3 BNi-7

Nicrobraz S-Binder

982 888 1020

1083

1090

10-3

Torr 10-5 Torr

0.85 /s

0.85 /s

GMTC 2205 BNi-3

0.1 /s 0.067 /s

(15mm 2mm) 399MPa

359MPa

133MPa 119MPa 0.85 /s

111.4MPa

GMTC 2205

0.067 /s

15

BNi-3

3

2205

-29-

2205

0.85 /s

0.1 /s 0.067 /s 6

FeCl3 6

0.85 /s

Avesta 2205 (0.05

mg/mm2) GMTC 2205 (0.006 mg/mm2)

PRE 1

2 2 0 5

PRE(Pitting Resistance Equivalent) GMTC

2205 Avesta 2205 36.97

33.53

GMTC PRE

6 2205 0.1 /s

0.067 /s

(0.85 /s) Wilms (7)

GMTC 2205

Avesta 2205

7 GMTC 2205 BNi-3 BNi-7

7 GMTC 2205

6

0.02mm

15mm 10mm 4mm

Avesta

2205 BNi-3 BNi-7

GMTC 2205

8

6 FeCl3

47.5 24

GMTC 2205

FeCl3

0.2mg/mm2 0.01 mg/mm2

GMTC 2205

Avesta 2205

9

GMTC 2205

Avesta 2205 2205

-30-

89 12

PRE

0.067 /s Avesta 2205

GMTC 2205 12.1

17.5 6 FeCl3

Avesta 2205

GMTC 2205

NSC89-2216-E-036-

021

1. J. O. Nilsson: Mater. Sci. Techno., 8 (1992) 685.

2. J. Charles, Welding in the World, 36 (1995) 43.

3. R.A. Walker: Mater. Sci. Techno., 4 (1988) 78.

4. P.H. Pumphrey, G.D.W. Smith and M. Prager: Mater.

Sci. Techno., 6 (1990) 209.

5. K. Beklers: Welding in the World, 36 (1995) 111.

6. Potgieter: British Corrosion Journal, 27(3) (1992)

219.

7. M. E. Wilms, V. J. Gadgil, J. M. Krougman and F. P.

IJsseling: Corrosion Science, 36 (1994) 871.

8. , , : , 12(2) (1998)33.

9. , , : , 12(4)

(1998),29,

10. ASTM G48-92, 1992, ASTM.

11. , : 88 ,

(1999).

12. , , 1999, p. 32.

13. C. O. A. Olsson, P. E. Arnvig: Corrosion Science,

37 (1995) 1201.

1 (wt%)

Table1 Chemical compositions of two duplex stainless

steels (wt )

Fe C Si Mn Cr Ni Mo N Cu

GMTC 64.2 0.04 0.5 1.65 22.7 5.4 3.45 0.18 0.06

Avesta 65.9 0.02 0.5 1.22 22.4 5.1 2.5 0.18 0.27

2 (wt%)

Table 2 Chemical compositions of filler metal

Filler Chemical Compositions

Cr B Si Fe P Ni Cu

BNi-3 -- 3.13 4.5 0.5 0.02 bal --

BNi-7 14.0 0.01 0.10 0.2 10.1 bal --

Cu foil -- -- -- 0.1 -- 0.2 bal

3

Table 3 Shear strength of vacuum brazed joints for two

duplex stainless steels

Material Filler Metal Cooling Rate Shear Strength

( /s) (MPa)

BNi-3 0.85 111.4

0.1 399*(133)

0.067 359*(118)

BNi-7 0.85 78.8

0.1 62.7

0.067 62.1

GMTC Cu foil 0.85 172.7

2205 0.1 458*(153)

DSS 0.067 359*(119)

BNi-3 0.85 117.8

0.1 135.3

0.067 116.1

BNi-7 0.85 68.2

0.1 54.7

0.067 46.4

Cu foil 0.85 200

0.1 236

0.067 226

*Fractured at Duplex Stainless Steel; Strength was

obtained by divided the fractured area, 15mm 2mm,

and the ( ) value implied the value divided the brazed

area.

-31-

2205

1

Fig. 1 Schematics of the brazed joints.

(a)

(b)

2 2205

(a) GMTC, (b) Avesta

Fig. 2 Microstructures of two as-received duplex

stainless steels electroetched in oxalic acid: (a)

GMTC 2205 and (b) SAF 2205.

-32-

89 12

(a)

(b)

(c)

3 GMTC 2205 1050

(a) 0.85 /s, (b) 0.1 /s, (c) 0.067 /s

Fig. 3 Microstructures of GMTC 2205 duplex stainless

steel after 1050 solution treatment for different

cooling rates, (a) 0.85 /s, (b) 0.1 /s, (c) 0.067

/s, electroetched in oxalic acid.

(a)

(b)

(c)

4 Avesta 2205 1050

(a) 0.85

/s, (b) 0.1 /s, (c) 0.067 /s

Fig.4 Microstructures of Avesta 2205 duplex stainless

steel after 1050 solution treatment for different

cooling rates (a) 0.85 /s, (b) 0.1 /s, (c) 0.067

/s, electroetched in oxalic acid.

-33-

2205

(a)

(b)

(c)

5 GMTC 2205 1050

Groesbeck (a)

0.85 /s, (b) 0.1 /s, (c) 0.067 /s

Fig.5 Microstructures of GMTC 2205 duplex stainless

steel after 1050 solution treatment for different

cooling rates, (a) 0.85 /s, (b) 0.1 /s, (c) 0.067

/s, etched in Groesbeck solution.

6 2205 6 FeCl3

47.5 24

Fig. 6 Weight lost of DSS specimens immersed in 6

FeCl3 solution at 47.5 for 24 hours.

7 GMTC 2205 6

FeCl3 47.5 24

Fig. 7 Weight lost of GMTC 2205 DSS brazed joints

immersed in 6 FeCl3 solution at 47.5 for 24

hours.

-34-

89 12

9

(a) BNi-3 (b) BNi-7 (c) Cu foil

Fig. 9 The corroded morphologies of brazed joint after

the immersion tests, (a) BNi-3, (b) BNi-7, (c) Cu

foil.

8

6 FeCl3

47.5 24

Fig. 8 Weight lost of two air cooled DSS and their

brazed joints immersed in 6 FeCl3

solution at

47.5 for 24 hours.

(a)

(b)

(c)