Hill Engineering Blog

AS7045 – Residual Stress Measurement and Classification, Metallic Structural Alloy Products and Finished Parts

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.

As AS7045 states “The purpose of this standard is to provide uniform methods for defining, quantifying, and classifying the residual stress in metallic structural alloy products and finished parts. These stresses may exist within a single element, or they may be the result of a joining process. Such quantification and classification may be required when residual stresses within mill stock or preforms can impact further in-process distortion during machining or other processes, and when residual stresses within finished components can impact final mechanical properties and performance (especially strength, durability, and fracture performance).”

This standard is a direct result of US Air Force funded projects with Hill Engineering (Small Business Innovation Research (SBIR) program) and Lockheed Martin (Metals Affordability Initiative) dating back to 2017. The standard includes 4 different residual stress categories:

  • Category 1: Bulk Residual Stress
  • Category 2: Joining Residual Stress
  • Category 3: Engineered Residual Stress
  • Category 4: Specified Target Residual Stress

For each category there are specific limits on the magnitude and level of consistency in the residual stress field based on the classification assigned (A through E).

Many of the residual stress measurement techniques that are referenced in the standard are ones that we perform at Hill Engineering, so if you have been keeping up with us, they are sure to look familiar.

If you are interested, the standard is available for purchase here. If you have any questions about the standard, or how you can effectively utilize it to benefit your organization, please feel free to contact us.