| Abstrakt: |
1.Nonfulfillment of the specified heat treatment may lead to formation of excess phases in the form of large light inclusions, films in the grain boundaries, and colonies of fine needles in castings of alloy 06KhN28MDTL after quenching. Microprobe analysis showed that all of them have the same composition: 37.0–39.0% Cr, 9.0–10.5% Mo, 1.6–2.0% Si, 14.0–16.0% Ni, and 31.0–33.0% Fe (carbon determined qualitatively), with high (in comparison with austenite) concentrations of Mo, Cr, Si, and C and low concentrations of Ni and Fe.2.Brittle intermetallic phases in castings of alloy 06KhN28MDTL are thermally stable and do not go into solution at temperatures up to 1200°, which excludes the possibility of correcting the structure of shaped castings by repeated heat treatment.3.To prevent precipitation of intermetallic phases in shaped castings, we recommend that the chemical composition of alloy 06KhN28MDTL be corrected — reduction of the molybdenum content to 2.4–2.8%, chromium to 21.0–23.0%, and limiting the silicon content to 0.6% and the amount of residual aluminum to 0.08%. |
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