SYMPOSIA PAPER Published: 01 January 1997

Reducing Stress Related Problems in Steel Forgings Using Sub-Harmonic Vibrational Energy


There are predominantly three residual stress related problems plaguing steel forgings. They are 1) distortion following machining, 2) delayed distortion, and 3) premature cracking tendencies. The major source of these problems is the stress caused by a sharp temperature drop from hot forging or welding.

This paper will detail SUB-harmonic vibrational technology as an effective stress relief solution to reducing these problems. Also, this paper will outline the three step approach for using the sub-harmonic energy process during welding. When used during welding additional benefits of reducing weld distortion and cracking will be achieved.

Data collected from seven Test Cases will be presented including reduced machine distortion (43–76%) from forged cannon barrels and aerospace components. Reducing premature cracking will be demonstrated using examples of longer fatigue life (200–400%) from components such as forged crankshafts and connecting rods used in racing engines. Data from the U.S. Department of Energy sponsored study on this technology will be presented. This report concluded that there is evidence that the Sub-harmonic treated and thermal stressed relieved specimens are “comparable.”

Author Information

Hebel, TE
Bonal Technologies, Inc., Southfield, Michigan
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Developed by Committee: A01
Pages: 148–159
DOI: 10.1520/STP16599S
ISBN-EB: 978-0-8031-5349-3
ISBN-13: 978-0-8031-2423-3