Abstract
The effects of heat treatments of the industrial type (eight-hour hold times at temperatures between 600 °C and 1000 °C) on the structural, mechanical, and corrosion resistance characteristics of weld alloy 625 have been studied. During the heat treatment, the mean concentration ratios of Nb, Mo, Si, Cr, Ni, and Fe elements between the interdendritic spaces and dendrite cores show little evolution up to 850 °C. Beyond that temperature, this ratio approximates 1, and the composition heterogeneity has practically disappeared at 1000 °C. An eight-hour heat treatment at temperatures between 650 °C and 750 °C results in increased mechanical strength values and reduced ductility and impact strength linked to the precipitation of body-centered tetragonal metastable intermetallic γ″ Ni3Nb phase in the interdendritic spaces. An eight-hour treatment in the temperature range between 750 °C and 950 °C has catastrophic effects on all mechanical characteristics in relation with the precipitation, in the interdendritic spaces, of the stable orthorhombic intermetallic δ Ni3(Nb, Mo, Cr, Fe, Ti) phase. At 1000 °C, the ductility and impact strength are restored. However, the higher the heat treatment temperature, the weaker the mechanical strength. Heat treatments have no effect on the pitting resistance of weld alloy 625 in sea water. The comparison of the results of this study on weld alloy 625 with those previously obtained on forged metal 625 shows that heat treatments below 650 °C and above 1000 °C are the sole treatments to avoid embrittlement and impairment of the corrosion resistance characteristics of alloy 625.
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References
R. Cox:Corros. Maintenance, 1985, vol. 8, pp. 97–98.
R.M. Nugent:Weld. J., 1986, vol. 65, pp. 33–39.
A. Van Bemst and Ph. Dargent:Met. Constr., 1983, vol. 15, pp. 730–33.
C.E. Stevens and R. Ross, Jr:J. Mater. Energy Syst., 1986, vol. 8 (1), pp. 7–11.
P. Koshy: 17th Offshore Technology Conference, Houston, TX, May 1985, vol. 3, OTC, Richardson, TX, pp. 145–53.
S.C. Hayes: Report No. DE81030005, G.E.C. Knolls Atomic Power Laboratory, Schenectady, NY, Sept. 1981.
J.P. Hammond: ASME Winter Annual Meeting on Ductility and Toughness Considerations in Elevated Temperature Service, San Francisco, CA, Dec. 1978, ASME MPC8, pp. 63–67.
K. Krompholtz, R. Tipping, and G. Uhlrich:Z. Werkstofftech, 1984, vol. 15, pp. 199–206.
C. Vernot-Loier and F. Cortial: inSuperalloys 718, 625 and Various Derivatives, E. Loria, ed., TMS, Warrendale, PA, 1991, pp. 409–22.
G. Cliff and G.W. Lorimer:J. Microsc, 1975, vol. 103, pp. 203–07.
M.J. Carr and W.F. Chambers:J. Microsc, 1984, vol. 134, Part 1, pp. 55–72.
V. Cihal, J. Furuchova, and J. Kubelka:Werkst. Korros., 1976, vol. 27, pp. 782–87.
V. Cihal:Corros. Sci., 1980, vol. 20, pp. 737–44.
P. Novak, R. Stefec, and F. Franz:Corrosion, 1975, vol. 31, pp. 344–47.
P. Muraleedharan, J.B. Gnanamoorthy, and K. Prasad Rao:Corrosion, 1989, vol. 45, pp. 142–49.
A.P. Majidi and M.A. Streicher:Corrosion, 1984, vol. 40, pp. 584–93.
M.F. Maday, A. Mignone, and M. Vittori:Corros. Sci., 1988, vol. 28, pp. 887–900.
A. Mignone, A. Borello, and A. La Barbera:Corrosion, 1982, vol. 38, pp. 390–402.
M.J. Cieslak, G.A. Knorovsky, T.J. Headley, and A.D. Romig, Jr.:Metall. Trans. A, 1986, vol. 17A, pp. 2107–16.
M.J. Cieslak, T.J. Headley, T. Kollie, and A.D. Romig, Jr.:Metall. Trans. A, 1988, vol. 19A, pp. 2319–31.
M.J. Cieslak: Weld. Res. Suppl., 1991, pp. 49–56.
H.F. Merrick:Precipitation Process in Solids, K.C. Russell and H.I. Aaronson, eds., TMS-AIME, Warrendale, PA, 1978, pp. 161–201.
I. Kirman:J. Iron Steel Inst., 1969, vol. 207, pp. 1612–18.
M. Sundararaman, P. Mukhopadhyay, and S. Banerjee:Metall. Trans. A, 1988, vol. 19A, pp. 453–65.
F. Garzarolli, A. Gersha, and K.P. Francke:Z. Metallkd., 1969, vol. 60, pp. 643–52.
H. Bohm, K. Ehrlich, and H. Kramer:Metallurgy, 1970, vol. 24, pp. 139–44.
E. Schnabel, H.J. Schuller, and P. Schwaab:Prakt. Metallogr., 1971, vol. 8, pp. 521–27.
D.R. Muzyka:The Superalloys, C.T. Sims and W.C. Hagel, eds., John Wiley, New York, NY, 1972, pp. 113–43.
M. Schirra:Metallurgy, 1982, vol. 36, pp. 394–401.
M.J. Cieslak, T.J. Headley, and R.B. Frank:Weld. Res. Suppl., 1989, pp. 473–82.
J.F. Barker, E.W. Ross, and J.F. Radavich:J. Met., Jan. 1970, pp. 31–41.
G.E. Korth and C.L. Trybus: inSuperalloys 718, 625 and Various Derivatives, E. Loria, ed., TMS, Warrendale, PA, 1991, pp. 437–46.
R. Cozar, M. Rouby, B. Mayonobe, and C. Morizoy: inSuperalloys 718, 625 and Various Derivatives, E. Loria, ed., TMS, Warrendale, PA, 1991, pp. 423–36.
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Cortial, F., Corrieu, J.M. & Vernot-Loier, C. Influence of heat treatments on microstructure, mechanical properties, and corrosion resistance of weld alloy 625. Metall Mater Trans A 26, 1273–1286 (1995). https://doi.org/10.1007/BF02670621
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DOI: https://doi.org/10.1007/BF02670621