STRUCTURAL CHANGES AND CORROSION RESISTANCE OF THE Cr17Ni2 TYPE STEELS (in Russian)
Although ferritic-martensitic acid resistant stainless steels can be welded satisfactorily, the region next to the weldment has a lowered corrosion resistance in view of the structural changes caused by the heating. Investigation showed that such a localized overheating followed by cooling in air results in the formation of a martensitic structure with a microhardness of 545 to 649 kg/mm/sup 2/ under considerable reduction of the tensile strength. During annealing at 300 to 600 deg C, martensite and chromium carbide phases precipitate out, resulting in an impoverishment of the alloy in chromium, and yielding an annealed martensite with a reduced corrosion resistance. After annealing at 400 to 650 deg C, the intercrystalline corrosion becomes selective, attacking preferentially the martensite rather than the chromium-containing ferrite. At 680 to 700 deg C the martensite is completely decomposed into a mixture of ferrite and carbide, precipitating a stable chromium carbide on the grain boundaries. After further heating up to 1300 deg C, exposure to the corroding medium of CuSO/sub 4/ + H/sub 2/SO/sub 4/ results in intercrystalline corrosion. If austenitic electrodes are used for the arc welding, the welded goods must be annealed at 680 to 700 deg for 1 hr. (TTT)
- Research Organization:
- Scientific Research Inst. of Chemical Equipment, USSR
- NSA Number:
- NSA-15-006345
- OSTI ID:
- 4075534
- Journal Information:
- Metalloved. i Termichesk. Obrabotka Metal, Vol. Vol: No. 11; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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