Aluminum Plate vs. Aluminum Open Die Hand Forgings 3

[1inchrist]

We supply aluminum open & closed die forgings. A lot of our customers are now requesting material to Plate specs, ie, alloy-temper 7075-T651 per AMS-QQ-A-250/12. We quote them to alloy-temper 7075-T652 (Hand Forging) per AMS-QQ-A-367. Customers are asking us what they can tell their customers as to the ramifications of this substitution, if any. I know absolutely nothing about Plate and how it compares to a Hand Forging as far as strength, FTT, SCC, etc. Apparently there is a shortage of large cross-section plate and Hand Forgings appear to be their alternative. Typically, the Hand Forgings we supply for "hog outs" are for aerospace applications.
Would I be "correct" in saying that Hand Forgings perform better all the way around?? It seems they would be because of the working of the metal giving 3 definitive grain directions. Does Plate only have a longitudinal Grain?
Any advice/info would be greatly appreciated.
Sincerely,
Barry

 

[rerig]

Strange.

Many fittings are made from Hand Forgings and Some Repair Stations want to substitute Plate to Fabricate In-house.
I wonder if the people requesting the Plate Spec. just don't know the specification differences.
I have worked for Repair Stations for 15 years and I am always being asked to allow the use of Plate instead of Forging. NO, same as last time. (Management must have short term memory problems)
"But we have Plate in stock". "Well, why didn't you say so", "NO"

I think somewhere someone was a bit lazy and used the Plate Spec. from memory.

I don't know how to assist with your current problem. Just keep educating them. May be someday...nah probably not.

 

[aluminumphil]

Hi Barry:

I worked as an aluminum plate metallurgist years ago. For heavy section - 150mm thick - 7075-T651 plate there are only a few mills that can make it. Alcoa and Pechiney. For thick plate solution treated and stretched, depending on the starting ingot size, there can be center plane porosity that reduces the fatigue performance in the short transverse direction. Also, as I recall, 7076-T651 is suseptible to stress corosion cracking particularly at the t/10 plane. All in all, I would say that solution treating and quenching a forging should be better from a quench rate point of view, but stretching is a more uniform way to do cold work. If a part is specified as a forging, I would be reluctant to substitute a hogged out plate part. Plate grain flow is only in one direction.

Phil

 

[etch]

This is a major annoyance for me. Material selection for jobs should be primarily undertaken by the experts ie the person making the component.

We have had many times were we politely told customers that the material they required would be too expensive, would not run or would not rpovide properties.