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Stainless Steel Products Presents

Stainless Steel Products Presents FATIGUE LIFE IMPROVEMENTS OF GROUND SURFACES BY WIRE BRUSHING Grinding of Surfaces Causes Microchip Buildup Surface Burning Material Redeposition Surface & Subsurface Cracking Mechanical & Metallurgical Transformation

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Stainless Steel Products Presents

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  1. Stainless Steel Products Presents FATIGUE LIFE IMPROVEMENTS OF GROUND SURFACES BY WIRE BRUSHING

  2. Grinding of Surfaces Causes Microchip Buildup • Surface Burning • Material Redeposition • Surface & Subsurface Cracking • Mechanical & Metallurgical Transformation • Surface Tensile Residual Stresses

  3. Fine Grinding Low Work Speeds Small Cut Depths CBN or Diamond Grit Polishing Shot Peening Ball Burnishing Surface Coating/Nitriding Remedies to Minimize the Effects of Grinding and Improve Compressive Residual Stresses

  4. Wire Brushing • Fast and Easy • A Low Cost Alternative • Common for On-Line Polishing/Deburring • Good for Complex Geometries • Induces Hardening and Compressive Residual Stresses

  5. Purpose of Experiments • Measure Fatigue Life Enhancements on Stainless Steel Ground Surfaces Using Wire Brushing o Optimized Brushing Conditions criteria related to =>Residual Stresses => Work Hardening => Surface Roughness => Burr Formation • Investigate mechanisms of fatigue crack initiation and propagation • Establish the role of work hardening and residual stress on fatigue crack growth

  6. Experimental Procedures • Material: 304 Stainless Steel • Ground Surface: “V” shaped notched bar • Only the Notch was Ground or Brushed • Test Surfaces characterized by measuring roughness • Hardening characterized by microhardness measurements • Residual Stresses were evaluated using X-Ray methods • High Cycle Fatigue Tests used a 3 point bend geometry • Other effects measured include surface finish, and surface temperature

  7. S2 took 14 seconds S4 took 12 seconds Optimized Brushing Conditions

  8. Surface Preparation and Effects on Surface Quality

  9. Electron Microscopy Ground Surface 1000x Brushed Surface 2000x

  10. Work Hardening & Residual Stresses

  11. Fatigue Behavior

  12. Summary of Wire Brushing Benefits • Relatively Inexpensive and Simple Process • Fatigue Life Improvements resulting from o Peak & valley reductions on ground surfaces resulting in fewer potential sites for fatigue crack initiation • Work Hardening Effects resulting from o Higher surface hardening and deeper work hardened layer • Eliminates Thermal Micro cracks by: o Removing the thermally effected layer induced by grinding • Results in Higher Compressive Residual Stresses by: o Generating higher micro geometrical qualities and hardness • Higher Geometrical Qualities vs. Shotpeening with Similar Compressive Residual Stresses

  13. References Presented by: Ralph Rosenbaum Stainless Steel Products 561-T Acorn Street, Deer Park, NY 11729 Phone (888) 767-3040 Fax: (631) 243-1500 E-mail: Ralph@STAINLESSWIRES.COM Article By: Nabil Ben Fredj, Mohamed Ben Nasr, Amir Ben Rhouma, Chedly Braham, and Habib Sidhom, Fatigue Life Improvements of the AISI 304 Stainless Steel Ground Surfaces by Wire Brushing, ASM International 1059-9495, December 21, 2003, p 564-574 Article Web link: http://www.springerlink.com/content/b824020760543lg0/

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