Grain Structure of A286

================ Dave:

One quick question -- where did you buy the second batch of material and are the heat/cert numbers the same as the first batch?

I am taking the liberty of reposting your question to another newsgroup I subscribe to -- sci.engr.metallurgy. The very knowledgable people there should be able to give you a definitive answer and possibly suggest suppliers, heat treaters, etc.

==> Note to sci.engr.metallurgy -- please [cross] post responses to alt.machines.cnc

Thanks

Unka George (George McDuffee)

There is something to be said for government by a great aristocracy which has furnished leaders to the nation in peace and war for generations; even a democrat like myself must admit this. But there is absolutely nothing to be said for government by a plutocracy, for government by men very powerful in certain lines and gifted with the "money touch," but with ideals which in their essence are merely those of so many glorified pawnbrokers.

Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.

material and are the heat/cert numbers the same as the first batch?<

Thanks for responding. The new batch of material from Carpenter is a different heat lot and a larger diameter (it was all they had in stock). You were saying if small contaminants were in the material it could cause the dual-plex grain structure; on the drawing specs it requires the finished parts to be sampled for hardness, micro-structure and chemical analysis. We will compare the chemical analyses of the original material cert to the analysis done by MMA Laboratories in Huntington Beach, CA (the original certs indicate the material was made in the USA by Carpenter). Do you have any other theory on what can cause dual-plex grain structures? Also, can you recommend a good metallurgist? Thanks again, Dave

================ I suggest trying the sci.engr.metallurgy newsgroup -- very knowledgable people there.

I am out of my depth beyond knowing that contaminants can cause grain size/boundry problems. [I can however spin a good story about how "soft" malleable iron can wreck HSS broaches when contaminated with copper although well with in specifications...]

One other item you might want to check is to see exactly what heat treat process was used and how closely it is controlled. There can be a tendency for a heat treater to consolidate lots from different customers to reduce costs. Also see if any of the HT personnel are new and/or if the heat treater has been acquired as some sort of "roll-up" or "stealth chain" move.

Grasping at straws here, but have you had a microstructure done on the material *BEFORE* heat treating? If it is dual-plex before HT this might indicate something.

Let us know the rest of the story.

Unka George (George McDuffee)

There is something to be said for government by a great aristocracy which has furnished leaders to the nation in peace and war for generations; even a democrat like myself must admit this. But there is absolutely nothing to be said for government by a plutocracy, for government by men very powerful in certain lines and gifted with the "money touch," but with ideals which in their essence are merely those of so many glorified pawnbrokers.

Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.