A new Aerospace Standard, AS7045 – Residual Stress Measurement and Classification, Metallic Structural Alloy Products and Finished Parts, was recently published by SAE International. Hill Engineering was actively involved in the development of the standard along with many of our collaborators in the aerospace industry. AS7045 offers tremendous potential to revolutionize the management of residual stress during metallic material procurement.
When it comes to measuring residual stress in small test specimens, precision is paramount. The slitting method is well suited to this application due to the high accuracy of wire EDM machining. However, this method is not without its challenges, especially when applied to very small test specimens, such as the 0.022-inch diameter wire we recently measured.
Hill Engineering recently published new collaborative research in the International Journal of Advanced Manufacturing Technology titled Effects of high‑energy laser peening followed by pre‑hot corrosion on stress relaxation, microhardness, and fatigue life and strength of single‑crystal nickel CMSX‑4® superalloy and appears in International Journal of Advanced Manufacturing Technology. The abstract text is available here along with a link to the publication.
Strain gages feature in a large portion of the residual stress measurements we perform at Hill Engineering, which is why we pride ourselves on our ability to correctly choose and apply strain gages to fit any measurement needs.
Hill Engineering has been recently issued its second US patent for the DART™ measurement system. This updated device offers improved residual stress measurements within small-diameter pipe applications, allowing for more accurate analysis in both in-laboratory and non-laboratory settings.
TrueSlot® is an innovative technique for measuring near-surface residual stress that is more reliable than conventional techniques.
TrueSlot® is a residual stress measurement technique for generating a profile of residual stress versus depth from the material surface. The stress computation is similar to slitting but offers more sensitivity near the surface due to the proximity of the strain gage.
Additionally, TrueSlot® is globally less invasive than slitting because the volume of removed material is localized to the surface and does not typically extend through most of the specimen thickness.
A model of a completed TrueSlot® method measurement.
The physical application of TrueSlot® is like hole drilling, however instead of a shallow hole being milled into the body of a specimen containing residual stress, the material removed is a shallow slot. The strain released with each incremental slot depth is measured near the slot using a strain gage.
TrueSlot® is useful for
Production quality control applications
Applications requiring in-field measurements with portable equipment
Near-surface residual stress determination
Parts with large or complex geometry
Applications with challenging measurement access
Applications requiring rapid turn time
TrueSlot® was found to have better repeatability when compared with conventional x-ray diffraction.
Results from the method repeatability study which found TrueSlot® to be a more repeatable measurement method than XRD
We are very excited today because in this blog we cross an incredible milestone: our 200th post! That’s right. Since the inception of the Hill Engineering blog back in March 2016, we have published 200 times.
Let’s take a look back over the past 7 years of blogging bliss!
by Camille Fowler
