Overcoming Challenges in Residual Stress Measurements on Small Test Specimens Using the Slitting Method

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.

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New publication: 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

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.

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Publication alert – Multiscale framework for prediction of residual stress in additively manufactured functionally graded material

Hill Engineering recently published new research with collaborators from around the world including South Korea, Australia, China, and the United Kingdom. The work is titled Multiscale framework for prediction of residual stress in additively manufactured functionally graded material. The abstract text is available here along with a link to the publication.

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Hill Engineering’s DART issued second US patent!

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.

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TrueSlot® – near surface residual stress measurement

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 solid model block with a long but thin slot cut out of the top.
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.

A plot with depth and repeatability as the axis and two lines of data, one red, the other black. For most depths, the red line is higher than the black, signifying that XRD is less repeatable than slotting.
Results from the method repeatability study which found TrueSlot® to be a more repeatable measurement method than XRD

You can read about our repeatability study here.

TrueSlot® measurements are performed using our DARTTM system for automated residual stress measurement.

The Big 200! – Celebrating a milestone blog post

An orange and blue banner with a large 200 printed on it.

Gather round readers!

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!

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