Alloy 230
Alloy 230
(OP)
Has anyone any experience with what phases/precipitates should generally be observed in wrought and solution treated alloy 230? We have found grain boundary films which are high in Lanthanum.
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RE: Alloy 230
We use 230 for grids for ammonia burner baskets and what little Metallography was mainly looking at the grain size and oxides. I don't recall anyone mentioning anything about the La content. We done a lot more physical testing in efforts to improve the life of material.
http://www.haynesintl.com/230HaynesAlloy.htm
RE: Alloy 230
excellent creep resistance strength, oxidization and corrosion resistance. The main constituents are Ni-Cr-W and the strengthening mechanism is solid solution strengthening. This alloy has between 0.005 and 0.05 wt% Lanthanum in the material which improves oxidation resistance. I would expect some Lanthanum migration to grain boundaries which is how the element produces improvement in oxidation resistance. What levels of Lanthanum are you detecting at the grain boundaries?
RE: Alloy 230
We experienced brittle fracture during processing and on analyzing the fracture face on the SEM found La rich areas particularly on grain boundaries with La anywhere from 2 to 16% using EDX. We have also seen a phase which appears to be ~30% La and ~62% Ni. I've read some literature that suggests that La combines with P, in C-Mn clean steels but at too high a level it will precipitate as a brittle La-Fe eutectic phase at grain boundaries affecting strength and toughness. Not sure if this is the same for alloy 230, but La-Ni forms rather than La-Fe??
RE: Alloy 230
RE: Alloy 230
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RE: Alloy 230