Microstructure and Room Temperature Mechanical Properties of a New Corrosion-resistant Alloy GH945 for Oil and Gas Applications

摘要

The microstructure and mechanical properties of a new corrosion-resistant alloy GH945 with high strength for oil and gas production were studied in this paper. The results showed that the main precipitations of GH945 alloy after solution heat treatment and two-stage age hardening treatment were γ' and γ" phase, MC-type carbide, σ phase and M_(23)C_6-type carbide. The increase of primary aging temperature not only promoted the precipitation of o phase and film of continuous M_(23)C_6 carbide on the grain boundary, but also led to the coarsening of γ' and γ" phase, which resulted in the decrease of yield strength and impact toughness. Alloy with high Nb content had high strength but low impact toughness. The following heat treatment was preferably used to obtain the combination of high strength and excellent ductility and toughness for GH945 alloy: 1010 ℃/70 min, WQ+ 735 ℃/9 h + FC to 615 ℃/18 h, AC.