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The Fatigue Performance of High Temperature Vacuum Carburized Nb Modified 8620 Steel
Technical Paper
2007-01-1007
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The bending fatigue performance of high temperature (1050 °C) vacuum carburized Nb modified 8620 steel, with niobium additions of 0.02, 0.06 and 0.1 wt pct, was evaluated utilizing a modified Brugger specimen geometry. Samples were heated at two different rates (20 and 114 °C min-1) to the carburizing temperature resulting in different prior austenite grain structures that depended on the specific Nb addition and heating rate employed. At the lower heating rate, uniform fine grained prior austenite grain structures developed in the 0.06 and 0.1 Nb steels while a duplex grain structure with the presence of large (>200 μm grains) developed in the 0.02 Nb steel. At the higher heating rate the propensity for abnormal grain growth was highest in the 0.02 Nb steel and complete suppression of abnormal grain growth was achieved only with the 0.1 Nb steel. The fatigue properties were correlated with measurements of austenite grain size and grain size distributions, microhardness profiles, carbon profiles, and fracture behavior as evaluated with scanning electron microscopy resulting from the different modes of grain growth. The higher Nb alloys, processed to produce fine, uniform prior austenite grain structures exhibited the best fatigue performance as evidenced by higher endurance limits and higher low cycle fatigue life. The presence of large prior austenite grains in samples that exhibited abnormal grain growth enhanced fatigue crack nucleation leading to lower fatigue performance. The results indicate that controlling austenite grain coarsening characteristics during carburizing, through additions of niobium effectively limits grain growth and removes the susceptibility of austenite grain growth to heating rate, and subsequently increases fatigue performance.
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Thompson, R., Matlock, D., and Speer, J., "The Fatigue Performance of High Temperature Vacuum Carburized Nb Modified 8620 Steel," SAE Technical Paper 2007-01-1007, 2007, https://doi.org/10.4271/2007-01-1007.Also In
Steel Innovations, Fatigue Research, Sheet/Hydro/Gas Forming Technology & Advanced High Strength Steel Development
Number: SP-2103; Published: 2007-04-16
Number: SP-2103; Published: 2007-04-16
References
- Parrish G. Carburizing: Microstructures and Properties ASM Materials Park, OH 1999
- Davis J.R. Surface Hardening of Steels ASM Materials Park, OH 2002
- Krauss G. Steel: Heat Treatment and Processing Principles ASM Materials Park, OH 1990
- AlOgab K. “Austenite Grain-Size Control at Elevated Temperature in Microalloyed Carburized Steels” ASPPRC, Colorado School of Mines Golden, CO 2004
- AlOgab K.A. Matlock D.K. Speer J.G. Kleebe H.J. “The Effects of Heating Rate on Austenite Grain Growth in a Ti-Modified SAE 8620 Steel with Controlled Nb Additions” ISIJ 2007
- Irvine K.J. Pickering F.B. Gladman T. J. Iron Steel Inst. 1967 205 161 167
- Rios P.R. Materials Science and Technology 1988 4 4 324 327
- Narita K. Trans. Iron and Steel Inst. of Japan 1975 15 145
- Bertrand C. Bleck W. Hippenstiel F. Hoffmann F. Kueper A. Leppanen R. Pichard C. Smith H. “Development of Carburizing Steels for Ultra High Process Temperatures” European Commission, Report no. EUR 20630 2003
- Murakami T. Hatano H. Yaguchi H. “Effects of the Conditions of Nb Carbo-nitride Precipitate on Abnormal Grain Growth in Nb Added Case Hardening Steels” New Developments in Long and Forged Products Proceedings AIST June 2006
- Davidson S.G. “The Influence of Titanium on Grain Size During High-Temperature Carburizing” ASPPRC, Colorado School of Mines Golden, CO 2001
- Lagneborg R. Siwecki T. Zajac S. Hutchinson B. “The Role of Vanadium in Microalloyed Steels” Scandinavian Journal of Metallurgy 28 5 October 1999
- Palmiere E.J. Garcia C.I. DeArdo A.J. Metall Trans 1994 25A 2 277 286
- Speer J.G. Michael J.R. Hansen S.S. Metall Trans 1987 18A 211 222
- Hashimoto K. Tanaka T. Nishimori H. Hiraoka K. “Grain Growth Property of Ti-Modified Carburizing Steels” SAE Report No. 2005-01-0985 Warrendale, Pa 2005
- Gladman T. The Physical Metallurgy of Microalloyed Steels The Institute of Materials 1997
- Gladman T. Grain Size Control The Institute of Materials, Minerals, and Mining 2004
- Cornelissen B.E. “Alloying and Processing Approaches to Improved Bending Fatigue Performance of Carburized Gear Steels” ASPPRC, Colorado School of Mines Golden, CO 1999
- Cornelissen B.E. Krauss G. Matlock D.K. “Effects of Alloying and Processing on Surface Oxidation and Bending Fatigue of Carburized Steels” 5 th ASM Heat Treating Congress Gothenburg, Sweden 117 127 June 2000
- Wise J.P. Matlock D.K. “Bending Fatigue of Carburized Steels: A Statistical Analysis of Process and Microstructural Parameters” SAE Paper No. 2000-01-0611 2000
- Vander Voort G. Metallography Principles and Practice McGraw-Hill 555 1984
- Metallography Principles and Procedures Leco Corporation St. Joseph, MI 1996
- Honeycomb R. The Plastic Deformation of Metals Edward Arnold London 1984
- Spice J.J. Matlock D.K. Fett G. “Optimized Carburized Steel Fatigue Performance as Assessed with Gear and Modified Brugger Fatigue Tests” SAE Technical Publication # 2002-01-1003 SAE Warrendale, PA 2002
- Spice J.J. “Evaluation of Silicon and Boron Additions to Reduce Quench Embrittlement in Modified 4320 Carburizing Grade Steel” Colorado School of Mines Golden, CO 2006
- Hyde R.S. “Quench Embrittlement and Intergranular Oxide Embrittlement: Effects on Bending Fatigue Initiation of Gas-Carburized Steel” Colorado School of Mines Golden, CO 1994
- Hyde R.S. Krauss G. Matlock D.K. “Phosphorous and Carbon Segregation: Effects on Fatigue and Fracture of Gas-Carburized Modified 4320 Steel” Metall Trans 25A 6 1994 1229 1240
- Erven K.A. Matlock D.K. Krauss G. “Effect of Sulfur on Bending Fatigue of Carburized Steel” Journal of Heat Treating 9 27 35 1991
- Cohen R.E. Unpublished Research ASPPRC, Colorado School of Mines Golden, CO 1994