scholarly journals Numerical and Experimental Study of AlSi Coating Effect on Nugget Size Growth in Resistance Spot Welding of Hot-Stamped Boron Steels

2021 ◽  
Vol 5 (1) ◽  
pp. 10
Author(s):  
Ali Afzal ◽  
Mohsen Hamedi ◽  
Chris Valentin Nielsen
Keyword(s):  
Welded Joints ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Focal Point ◽  
The Body ◽  
Weld Nugget ◽  
Boron Steel ◽  
Resistance Spot ◽  
Boron Steels ◽  
Spot Welded

In recent years, increasing automotive safety by improving crashworthiness has been a focal point in the automotive industry, employing high-strength steel such as press hardenable steel (PHS). In addition to the improved strength of individual parts in the body of the vehicle, the strength of the resistance-spot-welded joints of these parts is highly important to obtain a safe structure. In general, dimensions of weld nuggets are regarded as one of the criteria for the quality of spot-welded joints. In the presented research, a three-dimensional axisymmetric finite element model is developed to predict the nugget formation in resistance spot welding (RSW) of two types of PHS: the uncoated and AlSi-coated 1.8 mm boron steel after hot stamping. A fully coupled electro-thermo-mechanical analysis was conducted using the commercial software package Abaqus. The FE predicted weld nugget development is compared with experimental results. The computed weld nugget sizes show good agreement with experimental values.

scholarly journals Effect of post-weld tempering treatment on performance of DP600 spot welded joint

2021 ◽  
Vol 66 (3) ◽  
pp. 125-136
Author(s):  
Li Hong ◽  
Liu Xusheng ◽  
Wang Bing ◽  
Li Zhuoxin
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Dual Phase Steel ◽  
The Body ◽  
Weld Nugget ◽  
Vehicle Body ◽  
Material Strength ◽  
Dual Phase ◽  
Resistance Spot ◽  
Tempering Treatment

In order to meet the increasing requirements of the automotive industry for material strength grades and performance, the application of advanced highstrength steel automotive panels, represented by dual-phase steel, in lightweight vehicle bodies is increasing. Resistance spot welding is the main joining process for vehicle body manufacturing. How to improve the tensile strength and fatigue performance of dual-phase steel resistance spot welding joints is of great significance to the welding structure of the body. In this paper, resistance spot welding of cold rolled DP600 dual phase steel in the welding current range of 9000A-12000A was carried out. The effects of post-weld tempering treatment on microstructure, microhardness, shearing and fatigue of joints were compared. The results show that the microstructure transformation occurs in the weld nugget area after post-weld tempering, and the tempered martensite appears to reduce the microhardness of the weld nugget area; the nugget diameters, tensile-shear strength and failure energy are all higher than those without tempering treatment; tempering improves the fatigue strength of the spot joints, and regardless of whether the welded joints are tempered, cracks are all generated near the heat affected zone of the joint after fatigue test.

scholarly journals Effect of Double Pulse Resistance Spot Welding Process on 15B22 Hot Stamped Boron Steel

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1279
Author(s):  
Hwa-Teng Lee ◽  
Yuan-Chih Chang
Keyword(s):  
Heat Input ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Double Pulse ◽  
Weld Nugget ◽  
Boron Steel ◽  
Welding Parameters ◽  
Tensile Shear ◽  
Resistance Spot

Double pulse resistance spot welding process by applying a second step welding current is a new pathway to alter the mechanical properties for advanced high strength steels. Herein, the resistance spot welding (RSW) of hot stamped boron steel 15B22 by one-step and two-step welding with different welding currents is investigated. The results of the tensile–shear test, size of the weld nugget, hardness distribution, microstructure, and failure mode of different welding parameters are analyzed. The weldment of the two-step RSW with a higher heat input exhibits a lower tensile–shear load and lower fracture energy when the size of the weld nugget is large. The microstructural study reveals the appearance of a partially melted zone and sub-critical heat affected zone in the weldment where the fracture readily occurred. Thus, the two-step RSW process weakens the strength of the sample, which is attributed to the partial softening in the weldment due to the higher heat input.

Influence of Nitrogen Atmosphere on Weld Nugget Morphology during Resistance Spot Welding of 304L Stainless Steel

2017 ◽  
Vol 753 ◽  
pp. 211-217 ◽  
Author(s):  
Khalid M. Hafez ◽  
Wan Ahmad Yusmawiza Yusoff ◽  
N. Fathy ◽  
M. Ramadan ◽  
Mona Ismail
Keyword(s):  
Stainless Steel ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Nitrogen Atmosphere ◽  
Weld Nugget ◽  
304L Stainless Steel ◽  
Shielding Gas ◽  
Aisi 304L ◽  
Resistance Spot ◽  
Spot Welded

The Resistance Spot Welding is most widely used as a joining process for stainless sheets. AISI 304L austenitic stainless steel offers the optimum combination of corrosion resistance and mechanical strength. Improving the microstructure of the spot-welded nugget has a great effect on the quality of sheet weld joints. The current research presents the influence of using nitrogen atmosphere on macro and microstructure morphologies of the spot-welded nugget of AISI 304L stainless steel. Results show that using nitrogen atmosphere as shielding gas improves the appearance and color matching of the welded nugget with base, but on the other hand, nitrogen atmosphere reduces the nugget size. In addition to the reduction of the total ferrite in the spot weld nugget, Skeletal d-ferrite / total ferrite ratio increases by using nitrogen shielding gas due to nitrogen diffusion in fusion welded nugget zone.

Simulating Thermoelectric Effect and Its Impact on Asymmetric Weld Nugget Growth in Aluminum Resistance Spot Welding

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Lin Deng ◽  
YongBing Li ◽  
Wayne Cai ◽  
Amberlee S. Haselhuhn ◽  
Blair E. Carlson
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Weld Nugget ◽  
Thermoelectric Effects ◽  
Element Analysis ◽  
Resistance Spot ◽  
Seebeck Coefficients ◽  
Nugget Growth ◽  
Simulation Results ◽  
The Impact

Abstract Resistance spot welding (RSW) of aluminum–aluminum (Al–Al) is known to be very challenging, with the asymmetric growth of the weld nugget often observed. In this article, a semicoupled electrical–thermal–mechanical finite element analysis (FEA) procedure was established to simulate the RSW of two layers of AA6022-T4 sheets using a specially designed Multi-Ring Domed (MRD) electrodes. Critical to the modeling procedure was the thermoelectric (including the Peltier, Thomson, and Seebeck effects) analyses to simulate the asymmetric nugget growth in the welding stage. Key input parameters such as the Seebeck coefficients and high-temperature flow stress curves were measured. Simulation results, experimentally validated, indicated that the newly developed procedure could successfully predict the asymmetric weld nugget growth. Simulation results also showed the Seebeck effect in the holding stage. The simulations represent the first quantitative investigation of the impact of the thermoelectric effects on resistance spot welding.

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