Well, I finally ran into a problem. Was preheating a Wagner 10"
skillet on my induction hob (375 D.f.) prior to browning some lamb,
and the pan self destructed. The damage was a radial crack from center
to edge, left of the handle, with the opening at the rim about 1/8".

Thoughts: The induction hob has a 5-6 inch induction unit. Apparently,
the center of the pan heated/expanded faster than the edge iron could
cope with. Result was a failure from the outer edge, inward. When the
pan cooled, the crack was all but invisible.

Conclusion: Underlying reason (composition of the iron, who knows?):

Maybe these older pans could take the heat of wood stoves and ovens,
because the heat was more even. I've used this preheating technique
over 12000 BTU gas burners with no problem. The problem seems to be in
that the induction unit can induce heat in the pan's center at a rate
that can exceed the ability of the rest of the pan to deal with, with
fatal results.

Too bad. Had that Wagner since 1964 and it was WELL seasoned!

Have to buy another pan and start over....... I guess.

Alex