Influence of heat treatments on microstructure, mechanical properties, and corrosion resistance of weld alloy 625

Journal Article · Mon May 01 04:00:00 EDT 1995 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02670621· OSTI ID:72792

Cortial, F; Corrieu, J M; Vernot-Loier, C ^[1]

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1. Centre d`Etude des Structures et Materiaux Navals, La Montagne (France)

The effects of heat treatments of the industrial type 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 1,000 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 {gamma}{double_prime} Ni{sub 3}Nb 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 {delta} Ni{sub 3}(Nb, Mo, Cr, Fe, Ti) phase. At 1,000 C, the ductility and impact strength are restored. However, the higher the beat 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 1,000 C are the sole treatments to avoid embrittlement and impairment of the corrosion resistance characteristics of alloy 625.

• Sponsoring Organization: USDOE
• OSTI ID: 72792
• Journal Information: Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 5 Vol. 26; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM
CORROSION RESISTANCE
EXPERIMENTAL DATA
INCONEL 625
IRON
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLYBDENUM
NICKEL
NIOBIUM
SILICON
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K