TEServices assesses turbine components in our metallurgical lab including life extension, failure analyses, as well as brazing, coating and welding qualifications. Our in-house capabilities include nondestructive testing (NDT), visual, 3D digital and scanning electron microscopy as well as automatic sectioning, grinding and polishing.
Furthermore, we provide heat treatments of samples, mechanical, oxidation and corrosion testing. TEServices performs this for end-users, end-user organizations, and end-users' suppliers, such as repair and coating facilities. TEServices prides itself on giving advice that is easy to understand, even for customers that are not metallurgically trained.
TEServices standard metallurgical evaluation is limited to visual microscopy and can usually be performed within 24 hours after receiving the sample. Advanced metallurgical evaluations also use an in-house Scanning Electron Microscope (SEM) to provide pictures at high magnifications up to 20,000X to define gamma prime (for nickel based super alloys) and other phases and abnormalities which is performed within a few days.
Some of the Services That TEServices Can Provide Include:
TEServices SEM evaluation of Rene N4 gamma prime at 7,500X magnification
For non-destructive metallurgical evaluation, a sample is taken in a repairable area (which can be blended or welded), such as the tip of the Trailing Edge of a turbine blade. After mounting, grinding and polishing, this sample is reviewed in the un-etched and etched condition, at low magnifications with visual microscopy, and at high magnifications with a Scanning Electron Microscope. This evaluation can be critical to define the proper repair scope, the need for cleaning, heat treatments, coatings, and possible limitations of operation.
Replica Metallurgical Evaluation
Sometimes, the metallurgical condition needs to be assessed without the removal of a sample. TEServices can grind and polish the surface, and microscopically evaluate the base material with, or without, replica technology at TEServices or at customer location. This information can provide insight of the metallurgical condition in order to assess the component without removal of a sample (especially at locations that would render the part scrap or require repair) or even removal from the turbine.
This technology has also been proven effective to evaluate the condition of Frame 7 FA row 0 compressor blades, turbine wheels and buckets using visual, digital and scanning electron microscopy. The evaluation can be performed in our lab within a couple of days.
Application of replica after polishing (left) and after etching 2000X digital picture (right)
TEServices Digital microscope evaluating fracture surface
TEServices can investigate why a turbine failure happened to avoid recurrence. TEServices has the equipment such as visual, digital (Keyence) and scanning electron microscopes, and metallurgical expertise, component and operational knowledge, to provide the best failure analysis.
TEServices SEM evaluation of Rene N4 recrystallization at 1,000X magnification
TEServices performs First Article Inspection (FAI) or qualification for end-users, OEMs, repair and coating facilities. Based on their own or our specifications; stripping, welding, brazing and coating processes are evaluated and qualified. Typical coating qualification reviews the coating chemistry and thickness, however, TEServices coating qualification includes: interface, un-melted particles, porosity, oxidation, and the amount of other contamination
When there are concerns such as NDT indications, over-firing, the turbine or running beyond OEM recommended life or inspection interval, TEServices can provide you with a more comprehensive evaluation. Life assessment combines metallurgical evaluation at critical locations with stress rupture testing. Stress rupture testing reveals the
true strength and ductility of the material at elevated temperatures. The life assessment evaluation together with the history of the component can determine the remaining lifetime of the component.
Life extensions of components can be performed after the above described metallurgical evaluations and mechanical testing, using models and other experiences of that specific component.
Since 2011, TEServices has completed destructive testing on more than 80 F-technology bucket/blades in order to perform metallurgical evaluations and mechanical testing (stress rupture, thermo-mechanical fatigue and low cycle fatigue) in new, As-Run, and as repaired condition to extend the component life for TEServices’ customers (see ASME paper: GT2012-68363, Extending useful life of F-class gas turbine components).
TEServices is obtaining material properties of new, aged and heat treated IN 738LC, GTD 111DS, MGA 1400DS and SX Rene N4 and N5 in research program together with EPRI and repair facilities for the life assessments and extensions.