This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Bending Fatigue Crack Characterization and Fracture Toughness of Gas Carburized SAE 4320 Steel
Annotation ability available
Sector:
Language:
English
Abstract
Crack initiation and propagation in an SAE 4320 steel gas carburized to a 1.0 mm case depth was examined in specimens subjected to bending fatigue. Cellulose acetate replicas of incrementally loaded specimens showed that small, intergranular cracks were initiated during static loading to stress levels just above the endurance limit. The intergranular cracks arrest and serve as initiation sites for semi-elliptical, transgranular fatigue crack propagation. The maximum depth of stable crack propagation was between 0.17 and 0.23 mm, a depth which corresponds to the maximum hardness of the carburized case. Three equations which provide approximations to the stress distribution in the fatigue specimens were used to calculate KIC for the carburized case with values of maximum applied stress and measured stable crack geometry. Although all three equations yielded values in good agreement with published values of KIC for high-carbon, hardened steels, the equation for a semi-elliptical, surface crack under a bending stress state was judged superior. Variations in KIC are discussed relative to crack initiation geometry, strain-induced austenite transformation, and residual stresses.
Recommended Content
Authors
Citation
Hyde, R., Cohen, R., Matlock, D., and Krauss, G., "Bending Fatigue Crack Characterization and Fracture Toughness of Gas Carburized SAE 4320 Steel," SAE Technical Paper 920534, 1992, https://doi.org/10.4271/920534.Also In
References
- Sauter J. Schmidt I. Schultz M. “Einflußgrößen auf die Leistungsfähigkeit Einsatzgehärteter Zahnräder” HTM 45 2 1990 98 104
- Cohen R.E. Haagensen P.J. Matlock D.K. Krauss G. “Assessment of Bending Fatigue Limits for Carburized Steel” SAE Technical Paper Series No. 910140 1991
- Krauss G. “Microstructure and Properties of Carburized Steels” Metals Handbook, Vol. 4: Heat Treating ASM International Materials Park, Ohio 1991 363 375
- Apple C.A. Krauss G. “Microcracking and Fatigue in a Carburized Steel” Met. Trans. 4 1973 1195 1200
- Magnusson L. Ericsson T. “Initiation and Propagation of Fatigue Cracks in Carburized Steel” Heat Treatment '79 The Metals Society London 1980 202 206
- Zaccone M.A. Kelley J.B. Krauss G. “Strain Hardening and Fatigue of Simulated Case Microstructures in Carburized Steel” Carburizing: Processing and Performance Krauss G. ASM International Metals Park, OH 1989 249 265
- Zipp R.D. Walter G.H. “A Fractographic Study of High Cycle Fatigue Fractures in Carburized Steel” Metallography 7 1974 77 81
- Pacheco J.L. Krauss G. “Microstructure and High Bending Fatigue Strength in Carburized Steel” Carburizing: Processing and Performance Krauss G. ASM International Metals Park, OH 1989 191 237
- Erven K.A. “The Effects of Sulfur and Titanium on Bending Fatigue Performance of Carburized Steels” Colorado School of Mines Golden, CO 1990
- Krauss G. “The Microstructure and Fracture of a Carburized Steel” Met. Trans. 9A 1978 1527 1535
- Obermeyer H.K. Krauss G. “Toughness and Intergranular Fracture of a Simulated Carburized Case in EX-24 Type Steel” J. Heat Treating 1 3 1980 31 39
- Ando T. Krauss G. “The Effect of Phosphorus Content on Grain Boundary Cementite Formation in AISI 52100 Steel” Met. Trans. 12A 1981 1283 1290
- Panhans M.A. Fournelle R.A. “High Cycle Fatigue Resistance of E9310 Carburized Steel with Two Different Levels of Surface Retained Austenite and Surface Residual Stress” J. Heat Treating 2 1 1981 54 61
- Richman R.H. Landgraf R.W. “Some Effects of Retained Austenite on the Fatigue Resistance of Carburized Steel” Met. Trans. 6A 1975 955 964
- Brandis H. Schmidt W. “Contribution to the Influence of Retained Austenite on the Mechanical Properties of Case Hardened Steels” Case-Hardened Steels: Microstructural and Residual Stress Effects Diesburg D.E. The Metallurgical Society of AIME Warrendale, PA 189 209
- Shea M.M. “Impact Properties of Selected Gear Steels,” SAE Report 780772
- Kelley B. “The Effect of Chromium on the Microstructure and Bending Fatigue Behavior of 0.82% Carbon, 1.75% Nickel, and 0.75% Molybdenum Steels” Colorado School of Mines Golden, CO 1984
- Residual Stress Measurements by X-Ray Diffraction SAE J784a 2nd 1971
- Brewer A.W. Erven K.A. Krauss G. “Etching and Image Analysis of Prior Austenite Grain Boundaries in Hardened Steels” Materials Characterization 27 1991 53 56
- Irwin G.R. “Crack-Extension Force for a Part-Through Crack in a Plate” J. Applied Mech. 1962 651 654
- Gallagher J.P. Giessler F.J. Berens A.P. Engle, R.M. Jr. USAF Damage Tolerant Design Handbook: Guidelines for the Analysis and Design of Damage Tolerant Aircraft Structures USAF Flight Dynamics Laboratory (AFWAL/FIBEC) Wright-Patterson Air Force Base, Ohio 1984 1.7.20 1.7.59
- Benthem J.P. Koiter W.T. “Asymptotic Approximations to Crack Problems” Methods of Analysis and Solutions of Crack Problems Sih G.C. Noordhoff, Leyden 1973 131
- Parrish G. Harper G.S. Production Gas Carburising Pergamon Press Oxford 1985 70 71
- Krauss G. “The Relationship of Microstructure to Fracture Morphology and Toughness of Hardened Hypereutectoid Steels” Case-Hardened Steels: Microstructural and Residual Stress Effects Diesburg D.E. Metallurgical Society of AIME Warrendale, PA 33 58
- Cameron T.B. Diesburg D.E. “The Significance of the Impact Fracture Strength of a Carburized Steel” Case-Hardened Steels: Microstructural and Residual Stress Effects Diesburg D.E. The Metallurgical Society of AIME Warrendale, PA 17 32