Under a microscope Tinker's Metallurgical Lab analyzing failures Published June 3, 2016 By Kimberly Woodruff Staff Writer TINKER AIR FORCE BASE, Okla. -- Who do you turn to when you want to find out how or why a part has cracked or failed? The staff in the Metallurgical Lab, that's who. The Metallurgical Lab, located in Bldg. 3001, is an engineering organization capable of analyzing material properties in order to predict how they will perform in their intended operational environment and, in many cases, why they failed. Materials engineers also support the production environment by determining whether a part can be salvaged and repaired, have its life extended, or if it needs to be condemned. "We are a material resource for depot customers, providing them with answers to very specific alloy operational or application questions," said Scot Roswurm, Metallurgical Lab supervisor and senior materials engineer with the 76th Maintenance Support Group. "When someone needs to reverse engineer a component or characterize how something was manufactured or how it failed, we can help with that." Mr. Roswurm said the lab's job is to give their customers "actionable information with respect to failure modes and root causes so that they can take effective steps to prevent reoccurrence, ensuring fleet readiness and flight safety." In the Metallurgical Lab, samples are examined and analyzed using a large array of analytical tools including high power microscopes, and the materials engineers are able to determine what happened - how it failed - or test and predict how a piece of metal reacts under different circumstances. The engineers are able to take a broken part and determine, for instance, what kind of fracture has occurred and what caused it, whether it experienced too much heat or if it suffered a brittle or ductile overload, fatigue, corrosion, or embrittlement. Tinker has the only large chamber scanning electron microscope (LCSEM) in the Air Force which also happens to be the largest in the world. In fact, there is only one other LCSEM in the United States - at West Kentucky University - large, but not even close to the same size. The others are in Germany and Japan. At an original cost of $2.25 million, the microscope paid for itself in just three years. The direct cost savings is conservatively estimated at $6.5 million. Mr. Roswurm said that number takes credit only for the actual analyzed parts saved and not the other associated parts that would have been condemned without the ability to non-destructively evaluate features of concern or conventionally detected anomalies. The cost savings continue to accrue in terms of parts saved and returned to service and in the avoidance of disruptions to the supply chain. "It is so important that we not only ensure mission readiness, but do it affordably and smart," said Mr. Roswurm. "We are aware of our need to be efficient and cost-effective, to be good stewards to the Air Force, our customers and the taxpayers." The Metallurgical Lab has three additional scanning electron microscopes (SEMs). Their traditional SEMs can magnify an object up to 100,000 times, while their newest field emission scanning electron microscopes (FESEMs) can magnify an object up to nearly a million times and provide some pretty extensive analyses. For instance, by scanning a material, their added software and detectors can determine its chemical makeup and identify any transferred or foreign materials in or on the sample. Rudy Villa, lead materials engineer, who is also the principal Electron Backscatter Diffraction (EBSD) expert, scans highly polished metal samples to look for crystallographic patterns that can identify grain orientations and distinguish different material phases and phase alignments. From such alignments Mr. Villa can determine the susceptibility of a given microstructure to crack. "The computing power is awesome, as is the software we use," said Mr. Villa. "The software can 'think' in three-dimensional space, and do it in a matter of seconds." "Capabilities such as this make us one of the best equipped metallurgical labs in the world," said Mr. Roswurm. There is always some intriguing reason or series of unique events that lead to a failure, so in a way, the Metallurgical Lab is a lot like crime scene investigators. Mr. Roswurm says every project is a unique case and that they let the physical evidence speak for itself. Customers provide as much background information as they can, and the Metallurgical Lab takes it from there. "Mishaps and failures typically involve and evolve from a series of decisions, activities and/or events. It is amazing to consider the various contributory circumstances that must come into alignment for an incident to occur, the removal of just one factor having the potential to prevent the loss of an asset," said Mr. Roswurm. "The goal of our investigations is to break the cycle, whether the issue involves maintenance practices, material selection, operational application, environment, original manufacturing or repair. Elimination of factors we can control is optimal, but at a minimum we want mitigation, improving or augmenting some aspect of the component or assembly so it will provide a warning or at least buy a little more time to get to the next inspection interval before it causes a problem."