High cycle fatigue of welded joints with aging influence

The present paper deals with experimental studies on the ultra-high cycle fatigue property of Q345 bridge steel. Using the ultrasonic fatigue testing technique, specimens of Q345 welded joint with hourglass shape were designed using an analytical method combining with the finite element method and then fatigue tested in air at room temperature under fully reversed cyclic loading conditions (R=-1). The results show that the S-N curves of welded joints and relative base material specimens show continuously decreasing tendency in the very high cycle regime (105-109 cycles). Fatigue property of welded joint is much lower than that of base material and the fatigue strength of welded joint is only 45.0% of base material. Fracture can still occur on welded joints beyond 5 106 cycles, which indicates the fatigue limit defined at lifetime of 5 106 cycles cannot guarantee a safe design.

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The Influence of Mismatch Effect on the High Cycle Fatigue Resistance of High Strength Steel Welded Joints

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1146.73 ◽

2018 ◽

Vol 1146 ◽

pp. 73-83 ◽

Cited By ~ 3

Author(s):

Ádám Dobosy ◽

Marcell Gáspár ◽

János Lukács

Keyword(s):

Fatigue Resistance ◽

Welded Joints ◽

High Cycle Fatigue ◽

Research Work ◽

High Strength Steels ◽

High Strength ◽

Cycle Fatigue ◽

Matching Problem ◽

Work Related ◽

Base Materials

The objective of this article is to present the newest results of our research work related to the high cycle fatigue resistance of advanced high strength steels. In order to determine and compare the fatigue resistance, high cycle fatigue (HCF) tests were performed on two strength categories (S690 and S960) of high strength steels including quenched and tempered (Q+T) and thermomechanical (TM) types. During the HCF tests base materials and their welded joints were investigated at different mismatch conditions (matching, undermatching, overmatching). Measured and analysed data about base materials and welded joints were compared and discussed. Statistical approach was applied during the preparation and the evaluation of the investigations, which increased their reliability. The parameters of the HCF design curves were calculated based on the Japanese testing method (JSME S 002-1981) which uses 14 specimens. During the evaluation the results were compared with each other and with literary data. According to the presented examinations the HCF resistance of the base materials is more advantageous than the welded joints. The TM steel indicated better fatigue resistance than the quenched and tempered one of the same category. The matching problem had influence on the HCF resistance of high strength steels, depending on the strength category and the steel type.

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Very High Cycle Fatigue Properties of Welded Joints under High Frequency Loading

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.647.817 ◽

2013 ◽

Vol 647 ◽

pp. 817-821

Author(s):

Chao He ◽

Yong Jie Liu ◽

Qing Yuan Wang

Keyword(s):

Base Metal ◽

Welded Joints ◽

High Cycle Fatigue ◽

Low Cycle Fatigue ◽

Fatigue Cracks ◽

Ambient Air ◽

Cycle Fatigue ◽

Very High Cycle Fatigue ◽

Ultrasonic Fatigue ◽

Very High

Very high cycle fatigue (VHCF) properties of welded joints under ultrasonic fatigue loading have been investigated for titanium alloy (TI-6Al-4V) and bridge steel (Q345). Ultrasonic fatigue tests of base metal and welded joints were carried out in ambient air at room temperature at a stress ratio R=-1. It was observed that the fatigue strength of welded joints reduced by 50-60% as compared to the base metal. The S-N fatigue curves in the range of 107~109 cycles of base metal and welded joints for both materials exhibited the characteristic of continually decreasing type. The fatigue failure still occurred after 107 cycles of loading, and the fatigue limit in traditional does not exist. The fatigue facture mainly located in the weld metal region at low cycle fatigue range, but in the fusion area in HCF and VHCF. Analysis of fracture surfaces analyzed by SEM revealed that the fatigue cracks initiated from welding defects such as pores, cracks and inclusions.

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High cycle fatigue of welded joints: The TCD experience

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2008.01.011 ◽

2009 ◽

Vol 31 (1) ◽

pp. 20-27 ◽

Cited By ~ 15

Author(s):

D TAYLOR ◽

D HOEY

Keyword(s):

Welded Joints ◽

High Cycle Fatigue ◽

Cycle Fatigue

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The Effect of the Filler Material Choice on the High Cycle Fatigue Resistance of High Strength Steel Welded Joints

Materials Science Forum ◽

10.4028/www.scientific.net/msf.885.111 ◽

2017 ◽

Vol 885 ◽

pp. 111-116 ◽

Cited By ~ 4

Author(s):

Ádám Dobosy ◽

János Lukács

Keyword(s):

Fatigue Resistance ◽

Welded Joints ◽

High Cycle Fatigue ◽

Material Selection ◽

Gas Metal Arc Welding ◽

Research Work ◽

Base Material ◽

High Strength ◽

Filler Material ◽

Cycle Fatigue

The objective of this article is to present the newest results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed both on SSAB WELDOX 700E (S690QL) quenched and tempered and VOESTALPINE ALFORM 960M (S960TM) thermomechanical high strength steels. Welded joints were made from these base materials, using gas metal arc welding (GMAW, MIG/MAG) with matching filler material. In the article, the performance of the welding experiments will be presented, especially with the difficulties of the filler material selection; along with the results of the HCF tests executed on the base material and its welded joints. Furthermore, our results will be compared with different literary data.

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