Improve resistance spot weld quality of advanced high strength steels using bilateral external magnetic field

2020 ◽  
Vol 52 ◽  
pp. 270-280 ◽  
Author(s):  
Lin Qi ◽  
Fangzhou Li ◽  
Ruiming Chen ◽  
Qingxin Zhang ◽  
Yongbing Li
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
High Strength Steels ◽  
High Strength ◽  
Spot Weld ◽  
Weld Quality ◽  
Resistance Spot ◽  
Advanced High Strength Steels ◽  
Resistance Spot Weld

scholarly journals Liquid Metal Embrittlement of Advanced High Strength Steel: Experiments and Damage Modeling

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5451
Author(s):  
Konstantin Manuel Prabitz ◽  
Mohammad Z. Asadzadeh ◽  
Marlies Pichler ◽  
Thomas Antretter ◽  
Coline Beal ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Damage Model ◽  
High Strength Steels ◽  
High Strength ◽  
Liquid Metal Embrittlement ◽  
High Ductility ◽  
Resistance Spot ◽  
Advanced High Strength Steels ◽  
Strain And Strain Rate ◽  
Resistance Spot Weld

In the automotive industry, corrosion protected galvanized advanced high strength steels with high ductility (AHSS-HD) gain importance due to their good formability and their lightweight potential. Unfortunately, under specific thermomechanical loading conditions such as during resistance spot welding galvanized, AHSS-HD sheets tend to show liquid metal embrittlement (LME). LME is an intergranular decohesion phenomenon leading to a drastic loss of ductility of up to 95%. The occurrence of LME for a given galvanized material mainly depends on thermal and mechanical loading. These influences are investigated for a dual phase steel with an ultimate tensile strength of 1200 MPa, a fracture strain of 14% and high ductility (DP1200HD) by means of systematic isothermal hot tensile testing on a Gleeble® 3800 thermomechanical simulator. Based on the experimental findings, a machine learning procedure using symbolic regression is applied to calibrate an LME damage model that accounts for the governing quantities of temperature, plastic strain and strain rate. The finite element (FE) implementation of the damage model is validated based on the local damage distribution in the hot tensile tested samples and in an exemplary 2-sheet resistance spot weld. The developed LME damage model predicts the local position and the local intensity of liquid metal induced cracking in both cases very well.

scholarly journals Influence of the Process Parameters on the Quality and Efficiency of the Resistance Spot Welding Process of Advanced High-Strength Complex-Phase Steels

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1545
Author(s):  
Gerardo Morales-Sánchez ◽  
Antonio Collazo ◽  
Jesús Doval-Gandoy
Keyword(s):  
Shear Strength ◽  
Frequency Converter ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Parameters ◽  
Resistance Spot ◽  
Welding Equipment ◽  
Advanced High Strength Steels

In this study, the effects of electrical characteristics of an inverter combined with main welding parameters on the resistance spot weldability of advanced high strength steels (AHSS) CP1000 is investigated. The main welding parameters, current and time, were varied. The effects on the geometry and microstructure of the weld spot, the diameter of the weld pad, the hardness, the shear strength, and the efficiency of the process were studied, and the results were compared for two switching frequencies of the medium frequency converter. Furthermore, the weldability lobes were obtained as a function of the shear strength, for both frequencies. This work shows that the quality of the welding, in the established terms, is better when a lower frequency is used, even though the parameterization of the welding equipment can be easier for higher frequencies.

Ductile Fracture from Spot Weld and Flange Edge in Advanced High Strength Steels

2017 ◽  
Vol 10 (2) ◽  
pp. 373-381 ◽  
Author(s):  
Kentaro Sato ◽  
Takayuki Futatsuka ◽  
Jiro Hiramoto ◽  
Kei Nagasaka ◽  
Akira Akita ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
High Strength Steels ◽  
High Strength ◽  
Spot Weld ◽  
Advanced High Strength Steels

Influence of Weld Imperfections on the Fatigue Behaviour of Resistance Spot Welded Advanced High Strength Steels

2014 ◽  
Vol 891-892 ◽  
pp. 1445-1450 ◽  
Author(s):  
Michael Rethmeier
Keyword(s):  
Fatigue Life ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Whole Body ◽  
Surface Cracks ◽  
Significant Drop ◽  
Resistance Spot ◽  
Advanced High Strength Steels ◽  
Body In White

The use of advanced high strength steels (AHSS) in the automotive body-in-white is increasing. Those steels are predominantly joined by resistance spot welding. For the performance of the whole body-in-white, the fatigue behaviour is of high interest, especially as during production, weld imperfections such as cracks and manufacturing-related gaps cannot be avoided. In this study the TRIP steel HCT690 was used as it is a typical advanced high strength steel in automotive production. The investigation into the influence of cracks was split depending on the crack location in the weld area. Surface cracks in the electrode indentation area as well as in the heat affected zone were produced during welding and analyzed. The results showed that surface cracks independent of their position have no effect on the fatigue life. The produced internal imperfections have shown only a marginal impact on the fatigue life. It was ascertained that gaps of 3 mm lead to a significant drop in fatigue life compared to gap free shear tension samples under a load ratio R of 0.1. This fact was attributed to decreased stiffness, higher transverse vibration and higher rotation between the sheets. Furthermore, FE-simulations have shown an increase in local stresses in gapped samples.

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