The Scanning Electron Microscope (SEM) image to the right was prepared as part of the failure analysis of a powder metal part that failed in service. The image was part of the analysis to answer the questions:

• Did the component meet specifications?
• Was there a manufacturing defect? If so, where was the defect introduced in the manufacturing process?
• Are other components from the same, or similar, production lots at risk?

The questions were answered by a combinations of this image, optical microscopy and process detective work (including talking with production operators).

The Transmission Electron Microscope (TEM) image to the right is from my associate's files. It is a cross section of a AISI 52100 steel miniature ball bearing inner race.

Failures during gyroscope testing stopped production for the the Apollo Lunar Landing and a Navy ballistic missile programs. The production halt jeapordized both lunar landings and fleet readiness.

All the solutions proposed by the bearing manufacturers (New Departure and Barden), and other experts, were tried - without success. One next step was using the best available technology to look deeper into the microstructure of old (good) and new (bad) bearings.

The image was taken in 1968. At the time, the only option beyond optical microscopy magnification was using TEM replicas. TEM images required polishing the sample, depositing a layer of chrome on the surface, removing the chrome layer (the replica) and imaging the replica in the electron microscope.

This, and other, TEM images were taken to determine differences in bearing steel microstructures among:

• Existing samples from New Departure bearing lots that were marginally acceptable in the past.
• The then current New Departure production.
• The then current Barden production.

No metallurgical differences were found that explained the differences in factory yield and field performance. While TEM did not provide the "solution," it was very valuable because the TEM results closed the door to "blaming" the metal.

My associate subsequently identified a change to the assembly and test system that was put into production. The changes increased service life for both new bearings by more than 5x and solved production yield issues.

This image of the cross section of a titanium sheet explosive welded to a tantalum sheet is a higher magnification of one of the welded layers of the image on the home page.

The picture illustrates the intense cold working done by the shock wave from the explosive detonation as the shock wave traveled across the plates to be welded together.

There is no evidence of intermetallic compound formation from the welding process.