A New Perspective on Fatigue Performance of Advanced High- Strength Steels (AHSS) GMAW Joints

Conference · Tue Jan 01 04:00:00 EST 2008

OSTI ID:934806

Feng, Zhili ^[1]; Chiang, Dr. John ^[2]; Kuo, Dr. Min ^[3]; Jiang, Cindy ^[4]; Sang, Yan ^[4]

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1. ORNL
2. Ford Motor Company
3. MIttal Steel
4. AET Integration, Inc

Weld fatigue performance is a critical aspect for application of advanced high-strength steels (AHSS) in automotive body structures. A comparative study has been conducted to evaluate the fatigue life of AHSS welds. The material studied included seven AHSS of various strength levels - DP 600, DP 780, DP 980, M130, M220, solution annealed boron and fully hardened boron steels. Two conventional steels, HSLA 590 and DR 210, were also included for baseline comparison. Lap fillet welds were made on 2-mm nominal thick sheets by the gas metal arc welding process (GMAW). Fatigue test was conducted under a number of stress levels to obtain the S/N curves of the weld joints. It was found that, unlike in the static and impact loading conditions, the fatigue performance of AHSS is not influenced by the HAZ softening in AHSS. There are appreciable differences in the fatigue lives among different AHSS. Changes in weld parameters can influence the fatigue life of the weld joints, particularly of these of higher strength AHSS. A model is developed to predict the fatigue performance of AHSS welds. The validity of the model is benchmarked with the experimental results. This model is capable to capture the effects of weld geometry and weld microstructure and strength on the fatigue performance experimentally observed. The theoretical basis and application of the newly developed fatigue modeling methodology will be discussed.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 934806
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON
GAS METAL-ARC WELDING
GEOMETRY
MICROSTRUCTURE
PERFORMANCE
SIMULATION
STEELS
WELDING