Development of AC-MIG welding process(Report 5). Application of AC-MIG narrow gap welding process for butt joints of 980MPa high strength steels.

The need for steel materials with increasing strength is constantly growing. The main application of such advanced high strength steels (AHSS) is the automobile industry, therefore the welding process of different types of AHSSs in dissimilar welding joint was investigated. To simulate the mass production of thin steel sheet constructions (such as car bodies) automated metal inert gas (MIG) welding process was used to weld the TWIP (twinning induced plasticity) and TRIP (transformation induced plasticity) steel sheets together. The welding parameters were successfully optimized for butt welded joints. The joints were investigated by visual examination, tensile testing, quantitative metallography and hardness measurements. The TRIP steel side of the joints showed increased microhardness up to (450-500 HV0.1) through increased fraction of bainite and martensite. Macroscopically the tensile specimen showed ductile behaviour, they broke in the austenitic weld material.

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Narrow Gap Welding Process using Ultra-Low Spatter CO2 Gas Shielded Arc Welding

JOURNAL OF THE JAPAN WELDING SOCIETY ◽

10.2207/jjws.85.194 ◽

2016 ◽

Vol 85 (2) ◽

pp. 194-196

Author(s):

Hiroyuki SUMI

Keyword(s):

Arc Welding ◽

Welding Process ◽

Gas Shielded Arc Welding ◽

Narrow Gap ◽

Narrow Gap Welding

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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

Applied Sciences ◽

10.3390/app11125728 ◽

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.

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

Volume 1: Processes ◽

10.1115/msec2017-2786 ◽

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.

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

ASME 2009 International Manufacturing Science and Engineering Conference, Volume 1 ◽

10.1115/msec2009-84080 ◽

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.

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

MATEC Web of Conferences ◽

10.1051/matecconf/201925407002 ◽

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1138.147 ◽

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.

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Thermal Diffusivity of Traditional and Innovative Sheet Steels

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.297-301.893 ◽

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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Real-Time Monitoring of the Weld Penetration State in Laser Welding of High-Strength Steels by Airborne Acoustic Signal

Volume 4: Cycle Innovations; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine ◽

10.1115/gt2009-59274 ◽

2009 ◽

Cited By ~ 3

Author(s):

Wei Huang ◽

Shanglu Yang ◽

Dechao Lin ◽

Radovan Kovacevic

Keyword(s):

Laser Welding ◽

Real Time ◽

Optical Sensors ◽

Weight Ratio ◽

Welding Process ◽

High Strength Steels ◽

High Strength ◽

Acoustic Signals ◽

Real Time Monitoring ◽

Laser Welding Process

Nowadays high-strength steels have great applications in different industries due to their good combination of formability, weldability, and high strength-to-weight ratio. To guarantee a high quality without the presence of defects such as partial penetration (PP) in the laser welding of high-strength steels, it is very important to on-line monitor the whole welding process. While optical sensors are widely applied to monitor the laser welding process, we are proposing to use a microphone to acquire the airborne acoustic signals produced during laser welding of high-strength steel DP980. In order to extract valuable information from a very noisy signal acquired in a harsh environment such as industrial welding, spectral subtraction (SS), a noise reduction method is used to process the acquired airborne sound signals. Furthermore, by applying the power spectrum density (PSD) estimation method, the frequency characteristics of the acoustic signals are analyzed as well. The results indicate that the welds in full penetration (FP) and PP produce different signatures of acoustic signals that are characterized with different sound pressure levels and frequency distributions ranging from 500 Hz to 1500 Hz. Based on these differences, two algorithms are developed to distinguish the FP from PP during the laser welding process. A real-time monitoring system is implemented by a LabVIEW-based graphic program developed in this research. A feedback control system that could guarantee the FP will be developed in the near future.

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