Investigation of the Cleaning and Welding Steps From the Friction Element Welding Process

2017 ◽  
Author(s):  
Jamie D. Skovron ◽  
Brandt J. Ruszkiewicz ◽  
Laine Mears ◽  
Tim Abke ◽  
Ankit Varma ◽  
...  
Keyword(s):  
Weld Zone ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Process Time ◽  
Friction Element ◽  
Joint Quality ◽  
Head Height ◽  
Friction Element Welding ◽  
Step Parameters

The requirement of increased fuel economy standards has forced automakers to incorporate multi-materials into their current steel dominant vehicles in order to lightweight their fleets. Technologies such as Self Piercing Rivets and Flow Drill Screws are currently implemented for joining aluminum to high-strength steels but only one-technology is viable for joining aluminum to ultra-high-strength steels without pre-holes, namely Friction Element Welding. This study is aimed at investigating how variations in the cleaning and welding steps of the Friction Element Welding process influence joint quality. A design of experiment was conducted to understand the influence of key process parameters (endload, spindle RPM, and relative distance) during these steps on the pre-defined joint quality metrics of head height, weld zone diameter, under-head fill area, temperature, and microhardness. It is found that cleaning step parameters have the greatest influence on process time and energy consumption, while welding step parameters greatly influence maximum torque on the element, head height, and underhead fill, with both cleaning force and weld force influencing weld diameter, all parameters influence temperature.

Chipping Reduction Using Thermally-Assisted Friction Element Welding

2021 ◽  
Author(s):  
Amit B. Deshpande ◽  
Tyler J. Grimm ◽  
Laine Mears
Keyword(s):  
Aluminum Alloys ◽  
Chip Formation ◽  
High Strength ◽  
Energy Utilization ◽  
Process Time ◽  
Friction Element ◽  
Novel Method ◽  
High Strength Aluminum Alloys ◽  
Future Work ◽  
Friction Element Welding

Abstract The use of multiple material in the structural components of a vehicle allows for significant weight reduction. Friction element welding (FEW) is a novel method that allows the joining of two or more dissimilar material sheets. A limitation of this process is the chip formation in high strength aluminum alloys, which is observed as the protrusion of thin aluminum segments from under the head of the fastener. Chipping can degrade the joint’s strength over time due to accelerated crevice corrosion. A novel method is proposed to eliminate chip formation using thermal assistance. A grading scheme is developed to quantify the severity of chip formation. The effect of thermal assistance on chipping is analyzed. An investigation is also carried out to validate that the thermal assistance does not negatively affect the process time, energy, and joint strength. Thermal assistance is proposed to be a novel method of overcoming this limitation to allow more widespread use of the FEW process for higher-strength aluminum alloys. Future work will include the development of feasible, rapid methods of heating and measurement of energy utilization for implementation in the industrial environment.

Conduction Heat Assisted Friction Element Welding

2021 ◽  
Author(s):  
Tyler J. Grimm ◽  
Gowtham V. Parvathy ◽  
Laine Mears
Keyword(s):  
High Strength ◽  
Aluminum Sheet ◽  
Process Time ◽  
Friction Element ◽  
Critical Areas ◽  
Localized Heating ◽  
High Strength Aluminum Alloys ◽  
Friction Weld ◽  
Future Work ◽  
Friction Element Welding

Abstract Increasing awareness of global warming and strict government regulations have required the automotive industry to pursue lightweighting as an avenue towards increased vehicle efficiency. Lightweight designs typically rely heavily on multi-material use, which enables selective strengthening of critical areas without additional, unnecessary mass. Joining these materials during manufacturing has proven to be a challenging endeavor. Friction element welding (FEW) is one process that is capable of joining aluminum to steel. This two-sided joining technique utilizes a fastener to secure the aluminum sheet by creating a friction weld with the steel sheet. While this process is extremely robust for most materials, the FEW process can result in the extrusion of material from underneath the head of the fastener, termed chipping, which leads to corrosion and aesthetic issues. This behavior is typically seen in high strength aluminum alloys, such as 7075. A solution to chipping is implemented herein, which utilizes a modified downholder to conductively heat the aluminum sheet prior to the FEW process. This heating method was explored experimentally and through various numerical analyses. This method was found to be a viable option for relieving chipping. While the process time was only increased by a maximum of 2.5 seconds, faster, more localized heating should be targeted for future work.

Thermal-Mechanical Numerical Modeling of the Friction Element Welding Process

2018 ◽  
Author(s):  
Ankit Varma ◽  
Saheem Absar ◽  
Xin Zhao ◽  
Hongseok Choi ◽  
Tim Abke ◽  
...  
Keyword(s):  
Automobile Industry ◽  
Weight Ratio ◽  
Welding Process ◽  
Dissimilar Materials ◽  
High Strength ◽  
Element Model ◽  
Friction Element ◽  
Physical Mechanisms ◽  
Friction Element Welding ◽  
Good Agreement

To improve the fuel economy, the automobile industry is vigorously shifting towards using a mix of lightweight materials which offers high strength-to-weight ratio. Dissimilar material joining is of critical importance in this area. Friction element welding (FEW) has been proposed for dissimilar materials, with the capability of joining high strength materials of varying thickness in minimal time with low input energy. A coupled thermal-mechanical finite element model is developed in this work to better understand the physical mechanisms involved in the process and predict the evolution of parameters such as temperature, stress, material flow, and weld quality. The Coupled Eulerian-Lagrangian (CEL) approach is adopted to capture the severe plastic deformation of both the tool and the workpiece. The material deformation and temperature evolution are analyzed at different steps, and good agreement are shown between the simulation results and the experimental data.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

Cold Metal Transfer Spot Joining of AA6061-T6 to Galvanized DP590 Under Different Modes

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
HaiYang Lei ◽  
YongBing Li ◽  
Blair E. Carlson ◽  
ZhongQin Lin
Keyword(s):  
Heat Input ◽  
Mechanical Performance ◽  
Welding Process ◽  
High Strength ◽  
Metal Transfer ◽  
Cold Metal Transfer ◽  
Spot Joining ◽  
Predrilled Hole ◽  
Joint Quality ◽  
Cold Metal

In order to meet the upcoming regulations on greenhouse gas emissions, aluminum use in the automotive industry is increasing. However, this increase is now seen as part of a multimaterial strategy. Consequently, dissimilar material joints are a reality, which poses significant challenges to conventional fusion joining processes. To address this issue, cold metal transfer (CMT) spot welding process was developed in the current study to join aluminum alloy AA6061-T6 as the top sheet to hot dip galvanized (HDG) advanced high strength steel (AHSS) DP590 as the bottom sheet. Three different welding modes, i.e., direct welding (DW) mode, plug welding (PW) mode, and edge plug welding (EPW) mode were proposed and investigated. The DW mode, having no predrilled hole in the aluminum top sheet, required concentrated heat input to melt through the Al top sheet and resulted in a severe tearing fracture, shrinkage voids, and uneven intermetallic compounds (IMC) layer along the faying surface, leading to poor joint properties. Welding with the predrilled hole, PW mode, required significantly less heat input and led to greatly reduced, albeit uneven, IMC layer thickness. However, it was found that the EPW mode could homogenize the welding heat input into the hole and thus produce the most stable welding process and best joint quality. This led to joints having an excellent joint morphology characterized by the thinnest IMC layer and consequently, best mechanical performance among the three modes.

Noise Reduction During Acoustic Monitoring of Laser Welding of High-Strength Steels

2009 ◽  
Author(s):  
Wei Huang ◽  
Radovan Kovacevic
Keyword(s):  
Laser Welding ◽  
Noise Reduction ◽  
Acoustic Signal ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Penetration ◽  
Acoustic Signatures ◽  
Reduction Methods ◽  
Laser Welding Process

During the laser welding process of high-strength steels, different defects, such as a partial weld penetration, spatters, and blow-through holes could be present. In order to detect the presence of defects and achieve a quality control, acoustic monitoring based on microphones is applied to the welding process. As an effective sensor to monitor the laser welding process, however, the microphone is greatly limited by intensive noise existing in the complex industrial environment. In this paper, in order to acquire a clean acoustic signal from the laser welding process, two noise reduction methods are proposed: one is the spectral subtraction method based on one microphone and the other one is the beamforming based on a microphone array. By applying these two noise reduction methods, the quality of the acoustic signal is enhanced, and the acoustic signatures are extracted both in the time domain and frequency domain. The analysis results show that the extracted acoustic signatures can well indicate the different weld penetration states and they can also be used to study the internal mechanisms of the laser-material interaction.

scholarly journals Fatigue characteristics of welded high strength steel in the low cycle region of loading

2019 ◽  
Vol 254 ◽  
pp. 07002
Author(s):  
Peter Kopas ◽  
Milan Sága ◽  
Marián Handrik ◽  
Milan Vaško ◽  
Lenka Jakubovičová
Keyword(s):  
Low Frequency ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Loading Frequency ◽  
Fuel Savings ◽  
Fatigue Characteristics ◽  
Structural Parts ◽  
The One ◽  
Metal Welding

Automotive industry is the one of the most rapidly developing sector of engineering. Using of new, progressive materials can make significant benefits because of growing durability and reducing weight of structural parts, which can lead to the materials and fuel savings. The authors of this paper discuss fatigue characteristics on arc metal welding process of high strength steels STRENX 700MC obtained in low cycle region (N approximate to 1.10(3) divided byN= 1.10(7) cycles) at low-frequency loading (frequency approximate to 35 Hz, T = 20 +/5 degrees C,R= -1). Authors compares results of their own experimental works and subsequently discus these result and their possible effect on the fatigue lifetime of these steels.

Pulsed LASER-(Micro)TIG Welding of Automotive Dissimilar Zn-Coated Advanced High Strength Steels Thin Sheets in Overlap Configuration

2016 ◽  
Vol 1138 ◽  
pp. 147-152
Author(s):  
Aurel Valentin Bîrdeanu
Keyword(s):  
High Performance ◽  
Pulsed Laser ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Industrial Applications ◽  
Cost Ratio ◽  
Hybrid Welding ◽  
Thin Sheets ◽  
Advanced High Strength Steels

The development and implementation into a high number of industrial applications of materials categorized as (Advanced) High Strength Steels (AHSS) due to their high performance per cost ratio is more and more present and this trend is also combined with the development and implementation of new joining technologies and processes, including laser-arc hybrid processes.The paper presents the results of applying Pulsed LASER-(micro)TIG hybrid welding process, for realizing overlap joints for Zn-coated (A)HSS materials in dissimilar configurations, joints that were presented as designed based on UltraLight Steel Auto Body (ULSAB) principles.The influence of main hybrid welding process parameters was investigated in order to establish if one can obtain joints with high values for the shear strength resistance for some of the actually used dissimilar steel combinations based on designs applied throughout ULSAB project and the autos built following these principles.

scholarly journals Thermal Diffusivity of Traditional and Innovative Sheet Steels

2010 ◽  
Vol 297-301 ◽  
pp. 893-898
Author(s):  
Elena Campagnoli ◽  
Paolo Matteis ◽  
Giovanni M.M. Mortarino ◽  
Giorgio Scavino
Keyword(s):  
Thermal Diffusivity ◽  
Deep Drawing ◽  
Process Model ◽  
Twip Steel ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Low Carbon Steels

The low carbon steels, used for the production of car bodies by deep drawing, are gradually substituted by high strength steels for vehicle weight reduction. The drawn car body components are joined by welding and the welded points undergo a reduction of the local tensile strength. In developing an accurate welding process model, able to optimized process parameters and to predict the final local microstructure, a significant improvement can be given by the knowledge of the welded steels thermal diffusivity at different temperatures. The laser-flash method has been used to compare the thermal diffusivity of two traditional deep drawing steels, two high strength steels already in common usage, i.e. a Dual Phase (DP) steel and a TRansformation Induced Plasticity (TRIP) steel, and one experimental high-Mn austenitic TWIP (Twinning Induced Plasticity) steel. The low carbon steels, at low temperatures, have a thermal diffusivity that is 4-5 times larger than the TWIP steel. Their thermal diffusivity decreases by increasing temperature while the TWIP steel shows an opposite behaviour, albeit with a lesser slope, so that above 700°C the TWIP thermal diffusivity is larger. The different behaviour of the TWIP steel in respect to the ferritic deep drawing steels arises from its non ferro-magnetic austenitic structure. The DP and TRIP steels show intermediate values, their diffusivity being lower than that of the traditional deep drawing steels; this latter fact probably arises from their higher alloy content and more complex microstructure.

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