Effect of Weld Quality and Postweld Improvement Techniques on the Fatigue Resistance of Extra High Strength Steels

2008 ◽  
Vol 52 (7-8) ◽  
pp. 106-115 ◽  
Author(s):  
H. P. Lieurade ◽  
I. Huther ◽  
F. Lefebvre
Keyword(s):  
Fatigue Resistance ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Quality

Effect of Electrode Force Change on Spot Weld Quality of AHSS Using Servo Gun

2011 ◽  
Vol 189-193 ◽  
pp. 3359-3363 ◽  
Author(s):  
Cai Ping Liang ◽  
Xiao Hang Liu ◽  
Yue Wei Bai
Keyword(s):  
Spot Welding ◽  
High Strength Steels ◽  
Welding Current ◽  
High Strength ◽  
Weld Quality ◽  
Tensile Shear ◽  
Force Curve ◽  
Electrode Force ◽  
Different Thickness

Due to bad welds including small button, weld expulsion, and weld whisker etc., it is studied that the effect of constant and variable electrode force with servo gun on the weld quality of high strength steels with different thickness and materials. The results show that the electrode force plays an important role in resistance spot welding of AHSS as well as that of mild steels. Under the same welding current and time, better welds with higher tensile shear strength and larger nugget size can be obtained by optimizing electrode force curve using servo gun. The solutions could supply reference to study the prospect of servo gun in the joining of high strength steels.

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

2018 ◽  
Vol 1146 ◽  
pp. 73-83 ◽  
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.

Welding Properties and Fatigue Resistance of S690QL High Strength Steels

2015 ◽  
Vol 812 ◽  
pp. 29-34 ◽  
Author(s):  
Ádám Dobosy ◽  
János Lukács
Keyword(s):  
Fatigue Resistance ◽  
Welded Joints ◽  
Gas Metal Arc Welding ◽  
Research Work ◽  
Base Material ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Metal Arc Welding ◽  
Welding Properties

The objective of this article is to present the first results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed on RUUKKI OPTIM S690QL quenched and tempered high strength steel. In parallel these; welded joints were made on the same steel using gas metal arc welding (GMAW, MIG/MAG) to preparation of the cyclic investigations of the welded joints. In the article, the performance of the welding experiments will be presented; 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.

scholarly journals Imperfections and Modelling of the Weld Bead Profile of Laser Butt Joints in HSLA Steel Thin Plate

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 151
Author(s):  
Patricio G. Riofrío ◽  
José A. M. Ferreira ◽  
Carlos A. Capela
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Bead ◽  
Welding Parameters ◽  
Great Decrease ◽  
Weld Quality ◽  
Butt Joints

In many applications that use high strength steels, structural integrity depends greatly on weld quality. Imperfections and the weld bead geometry are influencing factors on mechanical properties of the welded joints but, especially in the fatigue strength, they cause a great decrease. The proper knowledge of these two factors is important from the nominal stress approach to the fracture mechanics approaches. Studies concerning the profile and imperfections of the weld bead in laser welding for thin plates of high strength steels are scarce. In this work, these two aspects are covered for five series single and double-welded joints, butt joints in a 3 mm thick HSLA steel, welded in a small range of welding parameters. The actual profiles captured with profilometer were modeled with proposed geometric parameters achieving an adequate fit with values of the coefficient of determination ℜ2 greater than 0.9000. Description of imperfections includes the distributions of porosity and undercuts. The evaluation of the weld quality, taking as guide the ISO 13919-1 standard determined B and D levels for the welded series while based on the stress-concentrating effect, showed a greater detriment in those series with undercuts and excessive penetration. The analysis of variance validated the results of the different combinations of laser welding parameters and showed, for the factorial experimental design, a more significant effect of the welding speed.

scholarly journals Safe choice of structural steels in a region of ultra-high number of load cycles

2019 ◽  
Vol 24 (24) ◽  
pp. 25-28 ◽  
Author(s):  
František Nový ◽  
Otakar Bokůvka ◽  
Libor Trško ◽  
Michal Jambor
Keyword(s):  
Fatigue Strength ◽  
Cyclic Loading ◽  
Fatigue Resistance ◽  
High Frequency ◽  
High Strength Steels ◽  
High Strength ◽  
Structural Steels ◽  
Experimental Results ◽  
Average Value ◽  
Continuous Decrease

Abstract In this paper the authors introduce their own selected experimental results in the field of the investigation of fatigue resistance of structural steels. The experiments were carried out on the nine structural steels including high strength steels, DOMEX 700MC, HARDOX 400, HARDOX 450, 100Cr6 (UTS from 446 MPa to 2462 MPa) at high-frequency cyclic loading (f = 20 kHz, T = 20 ± 5 °C, R = -1) in the region of number cycles ranged from N ≈ 2×106 to N ≈ 2×109 cycles of loading. The continuous decrease of fatigue strength in dependence on the number of loading cycles was observed with the average value of ratio σa2×109/σa2×106 = 0.69.

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