Cast iron is the least pure and brittle metal that can be made.
If the quality control at the start is poor I suspect its possible for impurities or unbalanced iron ratios to occur.

Is it possible therefore for this major structural piano component
to contain inherent flaws,undetectable to naked eye,to manifest themselves in differential movements causing eccentricities in tuning?

Mettallurgists please help.

Oh,yes,and there are some threads about plates breaking.

It turns out that these plates don't exhibit any kind of problem until years later,and some poor unsuspecting tech tunes the piano,the plate breaks,and the tech gets blamed for it.

This I know about from reading several posts here.

Actually plate breakage is a rare occurence, even with very old pianos.

The plate is not normally a factor in tuning instability.

Wrong forum, we`re the piano technicians.

You can find metallurgists here.

Mocheol:

It is a well disputed fact that the high sulfur alloy that was used in the construction of the Titanic is phlegmatically identical to the cast iron used in piano harps until 1936. (Someone from Ireland should already know this…) That is why, to this day, Lloyds of London will not insure the hull of a sea-going vessel that contains scrap iron from piano plates (harps.) Therefore pianos made before 1937 should never be tuned to A440 if they have ever been immersed in frigid saltwater.

“Therefore pianos made before 1937 should never be tuned to A440 if they have ever been immersed in frigid saltwater.”
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If an instrument was immersed in salt water I believe the plate would be the least of its problems…….

www.silverwoodpianos.com

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quote:
If an instrument was immersed in salt water I believe the plate would be the least of its problems…….
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Absolutely correct Dan

Yes cast iron is the least pure and most brittle metal made. But it's strong enough for the piano's tension. I read somewhere, that plates that do crack, have an inherent weakness resulting from the casting process. Maybe that's true, maybe not. I'm no expert and I doubt there are many metal experts in this forum.

The bottom line, cast iron has been used in pianos for what?, two hundred years almost. Yes, the mix for casting has changed, but I have tuned and pitch raised countless pianos made before 1937, and as long as the piano is not a three quarter plate, I will continue. Never had a problem. Strings break now and then, but never had a plate to go.

The philosophical context of this thread is rather amateurish at best.

Disputed? If so, why would you quote this information?

Phlegmatically identical? Phlegmatic means calm and unemotional. Was the Titanic's iron plating calm and unemotional?

I never saw the Titanic smile or get angry or upset so I guess the iron was phlegmatic. Until of course the iron came in contact with the ice and then the iron got all bent out of shape…….. :p

I have taken a plate and pounded it with a 20lb sledge until I was exhausted, right in the middle and no breakage. Pretty unusual for one to break.
Although, I have inspected an old Steinway D some years back that came out of the Arts Centre in Ottawa in 1971. The plate was fractured under the bass strings….got an old picture somewhere. I’ll see if I can find it.

www.silverwoodpianos.com

Uh, ... it's humor! Actually, I have it on poor authority that the fact was very well disputed, and that the hull of the Titanic was always very emotionally calm right up to this very day.

Gee! Ron's right. "The philosophical context of this thread is rather amateurish at best."

I figured if someone was trolling, I might as well give them a whopper.

Oh, and I bring 3/4 plates to A440 all the time. (Unless they had been immersed in frigid saltwater, of course...)