January 2010

Monday, January 11th, 2010

  • 5:45 Social / Networking Time
  • 6:30 Dinner
  • 7:30 Presentation

 

Characterizing and Using Residual Stresses to Benefit Fatigue Life” by Andrew M. Freborg, PE, Deformation Control Technology

The two most common causes of part failure are corrosion and fatigue. Residual stress can accelerate or slow down the microscopic processes that cause both types of failure. Fatigue will be the primary focus of this presentation. Residual tension on the surface of a part hurts life, while residual compression helps to extend part life. The presentation will look at some of the typical manufacturing process steps that effect residual stresses in metal parts. Modeling of the process steps with finite element analysis is used to understand metallurgically and mechanically how each process step alters the residual stress state. Experimental measurements and fatigue testing results are reported to corroborate the modeling results and demonstrate the effect of residual stress on fatigue life. Processes to be presented include carbuzation, heat treatment (quench hardening), and laser shock peening. Mechanical shot peening and cavitation peening will also be briefly discussed. Process simulation provides an important link between metallurgical engineering and mechanical design.

Andrew Freborg is a registered Professional Engineer (metallurgical engineering) in the State of Ohio. He is a graduate of the Illinois Institute of Technology, where he earned a B.S. from IIT’s College of Engineering in 1989.

Mr. Freborg’s career has been primarily focused on thermal processing of metals. Prior to joining Deformation Control Technology, he was employed with LTV/ Republic Engineered Steel as Senior Process Metallurgist within the primary steelmaking division of Republic’s principal production facility in Canton, OH. At Republic he focused on sophisticated production techniques and quality control relating to steel cleanliness, as-cast bloom quality, and properties developed in response to mechanical working and heat treatment. Since joining DCT, Mr. Freborg has worked extensively in adapting analytical engineering methods, such as finite element analysis, to address various quality/processing challenges within the ferrous metals industry. This includes continuous cast mold design and thermal stress characterization during solidification and post-cast processing.

Recent engineering work in collaborative programs with industry and the Department of Defense has included developing and validating thermal-stress characterizations of heat treated and laser shock peened alloy steel gears. This work is instrumental in facilitating improved fatigue life in aerospace transmission components. Andrew is a member of ASMI, HTS and the AIST.