GE titanium compressor case EB porosity (the acetone case)

Extended teaching case (~9 minutes, the longest narrative unit of the lecture). Two $30K titanium rings welded circumferentially in a chamber half the size of the room. Persistent porosity. Tom diagnoses: industrial-grade acetone (oil-contaminated, demonstrated via Newton's rings on a glass slide) + dust falling on the joint surface in the welding room. Fix: reagent-grade acetone. Savings: $500K/year. Tom: no credit, no payment, no letter of commendation; engineer Lyle got a letter.

The other industry is aerospace. GE — I think you can't do this anymore because they're closing it down — they used to weld together two turbine disks. I was called up there in the mid '80s by a guy I had worked with. Actually I had a resistance spot welding contract with General Electric. I spent the mid '80s in Tokyo, Japan with the US Office of Naval Research as a liaison scientist. Right before I left, General Electric came to me and said we'd like to give you a research contract on spot welding of combustor cans for our aircraft engines.