Laser Welding on Material Used for Automobile Lightweight

2012 ◽  
Vol 442 ◽  
pp. 389-392
Author(s):  
Qiang Wu ◽  
Lan Ying Xu ◽  
Yu Zhong Li
Keyword(s):  
Laser Welding ◽  
Heat Affected Zone ◽  
High Strength ◽  
Deep Penetration ◽  
Technological Parameters ◽  
Welding Stability ◽  
Zinc Coated Steel ◽  
Protective Gas ◽  
Deep Penetration Welding ◽  
The Relationship

Based on a large number of welding tests to automotive lightweight material by CO2 laser, the microstructures of welded joint were tested related to performance. on the condition of welding technology, the relationship between the lower critical power of stabile deep penetration welding and welding speed and the focus position is deduced, In a coaxial and side protective gas conditions, through the optimization of technological parameters laser deep penetration welding can effectively avoid heat affected zone of high strength zinc coated steel becomes soft, welded comprehensive quality has been effectively controlled. Zinc evaporates unsteadily, which leads to expansion of heat affected zone and reduction of welding stability, so in this paper effective measures are taken to control it. Experimental results show that a qualified welding quality can be obtained by optimized process parameters of laser welding and adopting argon as shielding gas.

Elucidation of Welding Stability Based on Keyhole Configuration during High-Power Fiber Laser Welding

2011 ◽  
Vol 314-316 ◽  
pp. 941-944 ◽  
Author(s):  
Xiang Dong Gao ◽  
Qian Wen ◽  
Seiji Katayama
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
High Power ◽  
Continuous Wave ◽  
High Energy ◽  
High Energy Density ◽  
Deep Penetration ◽  
Characteristic Parameters ◽  
Fiber Laser Welding ◽  
Welding Stability

During deep penetration laser welding, a keyhole is formed in the molten pool due to the intense recoil pressure of evaporation. The formation of the keyhole leads to a deep penetration weld with a high aspect ratio and this is the most advantageous feature of welding by high-energy-density beams. The configuration and characteristics of a keyhole are related to the welding stability. In a fiber laser butt-joint welding of Type 304 austenitic stainless steel plate with a high power 10 kW continuous wave fiber laser, an infrared sensitive high-speed video camera was used to capture the dynamic images of the molten pools. The configurations of a keyhole were analyzed through image processing techniques such as median filtering, wiener filtering and gray level threshold segmentation to obtain the edge of a keyhole. The width and the area of a keyhole were defined as the keyhole characteristic parameters, and the deviation between the laser beam and weld center as a parameter reflecting the welding stability. By analyzing the change of the keyhole characteristic parameters during welding process, it was found that these parameters were related to the welding stability. Welding experimental results and analysis of the keyhole characteristic parameters confirmed that the welding stability could be monitored and distinguished by a keyhole configuration during high-power fiber laser welding.

Residual Deformation Measurement of Laser Weldment Using the Laser Interferometry

2006 ◽  
Vol 326-328 ◽  
pp. 63-66
Author(s):  
Zhan Wei Liu ◽  
Da Qing Zou ◽  
Wu Zhu Chen ◽  
Wei Ning Wang ◽  
Yan Fang
Keyword(s):  
Experimental Data ◽  
Laser Welding ◽  
Heat Affected Zone ◽  
Strain Gradient ◽  
Stress Gradient ◽  
Residual Deformation ◽  
Laser Interferometry ◽  
Narrow Strip ◽  
Welded Seam ◽  
The Relationship

In this paper, the residual deformation induced in laser welding processing was studied by using the moiré interferometry and a novel high-temperature specimen grating technology. The experimental results indicate that the heat-affected zone of laser welding is a narrow strip. There exists great residual strain gradient in the heat-affected zone, especially great residual shear strain gradient. It implies that great residual stress and stress gradient exist near the welded seam. The relationship between the size of the heat-affected zone and the changes of the technology parameters were discussed in the experiments, which can supply some reliable experimental data for optimizing processing technology.

Microstructure and Mechanical Properties of Aluminum Alloy/High Strength Steel Double Beam Laser Deep Penetration Welded Joint

2019 ◽  
Vol 944 ◽  
pp. 448-457
Author(s):  
Hong Xi Chen ◽  
Li Cui ◽  
Dong Qi Lu ◽  
Yao Qing Chang ◽  
Xu Xia ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
High Strength Steel ◽  
High Strength ◽  
Deep Penetration ◽  
Mechanical Resistance ◽  
Lap Joint ◽  
Beam Laser ◽  
Double Beam ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding

A new dual beam laser deep penetration welding technology for lap joint of 1.5 mm thick aluminum alloy and high strength steel was explored in this paper, and the effects of three different beam energy ratios (RS=0.25,0.33,0.5) on weld formation, interface microstructure and mechanical properties were studied. The result shows that under certain conditions of other parameters, double beam laser deep penetration welding process can be applied to lap joint of aluminum alloy / high strength steel with good weld shape when RS=0.25,0.33,0.5. As RS increases from 0.25 to 0.5, the penetration of the weld reduces from 575 μm to 424.2μm, the thickness of intermetallic compound (IMC) layer at the interface between aluminum alloy and weld metal reduces from 3.4 μm to 2.5 μm, the average microhardness of the IMC layer decreases from 771.1 HV to 571.9 HV, the mechanical resistance of the joint raises from 95.7N/mm to 115.2N/mm. When RS=0.5, double beam laser deep penetration welding of aluminum alloy / high-strength steel joints has the highest mechanical resistance of joints, because of the relatively good plastic ductility of the joint.

scholarly journals Assessment of Heat-Affected Zone Softening of Hot-Press-Formed Steel over 2.0 GPa Tensile Strength with Bead-On-Plate Laser Welding

2021 ◽  
Vol 11 (13) ◽  
pp. 5774
Author(s):  
Kwangsoo Kim ◽  
Namhyun Kang ◽  
Minjung Kang ◽  
Cheolhee Kim
Keyword(s):  
Laser Welding ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welding Process ◽  
High Strength ◽  
Hardness Test ◽  
Fracture Initiation ◽  
Hot Press ◽  
Automotive Body ◽  
Martensitic Microstructure

High-strength hot-press-formed (HPF) steels with a fully martensitic microstructure are being widely used in the fabrication of automotive body structure, and 2.0 GPa-strength HPF steel has recently been commercially launched. However, heat-affected zone (HAZ) softening is unavoidable in welding martensitic steel. In this study, the HAZ softening characteristic of 2.0 GPa HPF steel was investigated by applying a high-brightness laser welding process, wherein the heat input was controlled by varying the welding speed. Microstructural evaluation and hardness test results showed that the base metal with a fully martensitic microstructure was changed to the same type of fully martensitic microstructure in the weld metal, while relatively soft microstructures of tempered martensite and ferrite phase were partially formed in the intercritical HAZ (ICHAZ) and subcritical HAZ (SCHAZ) areas. In the tensile test, the joint strength was 10–20% lower than that of the base metal, and the fracture initiation was estimated at the ICHAZ/SCHAZ boundary, where the lowest hardness was confirmed by the nanoindentation technique.

Modelling of Heat Affected Zone Softening in Laser Welding of M1500

2015 ◽  
Author(s):  
Hongze Wang ◽  
Yansong Zhang
Keyword(s):  
Temperature Distribution ◽  
Laser Welding ◽  
Heat Affected Zone ◽  
High Strength Steel ◽  
High Strength ◽  
Element Model ◽  
Hardness Measurement ◽  
Vehicle Body ◽  
Ultra High Strength Steel ◽  
Heat Affected Zone Softening

With the implementation of more stringent emissions standards, ultra-high strength steel has been increasingly used in vehicle body to reduce the carbon emissions, but softening in the heat affected zone is one of the most serious issues faced with in welding of this steel. In this paper, a finite element model (FEM) was developed to estimate temperature distribution in laser welding of ultra-high strength steel M1500 and a carbon diffusion model was then developed to estimate the martensite tempering transformation in the softening zone based on the simulated temperature distribution results. Maximum softening degree, minimum hardness point position and boundary of the softening zone were estimated and validated by hardness measurement experiments. This work provides a better understanding of the mechanism for heat affected zone softening in laser welding of ultra-high strength steel.

Investigation of Laser Welding on Vehicle Safety Parts

2010 ◽  
Vol 34-35 ◽  
pp. 1601-1604
Author(s):  
Qiang Wu ◽  
Yong Tang ◽  
Yong Qiang Yang ◽  
Yu Zhong Li ◽  
X.I. Qu
Keyword(s):  
Laser Welding ◽  
Focal Point ◽  
Weld Zone ◽  
High Strength ◽  
Tensile Specimen ◽  
Galvanized Steel ◽  
Experimental Result ◽  
Vehicle Body ◽  
Deep Penetration ◽  
Welding Seam

Based on many experiments of CO2 laser welding of high strength two-sided galvanized steel thick with 1.5mm to vehicle body, joint microstructure and stress-strain curves of specimen are acquired. It has inferred theoretically relations among critical power, welding speed and focal point position under given welding technological conditions. With coaxial and side-blown protective gas, craft parameter are optimized, the laser deep melt welding may avoid effectively heat-affected zone (HAZ) softened phenomenon, as well as welded porosity may controlled effectively. The experimental result shows that hardness value in weld zone becomes low with increasing of energy input, at the same time the cracked zone of tensile specimen, the dimple size and the distribution of cross-section in welding seam are also different, tensile crack of welding seam extends to the base metal, which indicates deep penetration laser welding can effectively avoid softening of welding joints during laser welding of high strength galvanized steel.

Detection of Seam Offset Based on Molten Pool Characteristics during High-Power Fiber Laser Welding

2012 ◽  
Vol 549 ◽  
pp. 1064-1068
Author(s):  
Jian Bin Liang ◽  
Xiang Dong Gao ◽  
De Yong You ◽  
Zhen Shi Li ◽  
Wei Ping Ruan
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
High Power ◽  
Molten Pool ◽  
High Energy ◽  
High Energy Density ◽  
Deep Penetration ◽  
Characteristic Parameters ◽  
Fiber Laser Welding ◽  
Deep Penetration Welding

Laser welding includes the heat conduction welding and the deep penetration welding. Deep penetration welding can not only penetrate the material completely, but also can vaporize the material. An important phenomenon during deep penetration welding is that molten pool in the weldment will appear a keyhole. The formation of the keyhole leads to a deep penetration weld with a high aspect ratio and this is the most advantageous feature of welding by high-energy-density beams. Small focus wandering off weld seam may result in lack of penetration or unacceptable welds, and largely reduce heating efficiency. In a fiber laser butt-joint welding of Type 304 austenitic stainless steel plate with a high power 6kW continuous wave fiber laser, an infrared sensitive high-speed video camera was used to capture the dynamic images of the molten pools. The configurations of molten pools were analyzed through image processing techniques such as median filtering, partial Otsu threshold segmentation and Canny edge to obtain the edge of keyholes and molten pools. The circular degree and the area of keyholes and the width and average gray of molten pools were defined as characteristic parameters to reflect the seam offset between the laser beam and the weld center. By analyzing the change of characteristic parameters during welding process, it was found that these parameters were related to the seam offset. Welding experimental results and analysis of characteristic parameters confirmed that the seam offset could be monitored and distinguished by molten pools configuration during high-power fiber laser welding.

Simulation Study on Laser Welding of High Strength Steel to Vehicle

2010 ◽  
Vol 143-144 ◽  
pp. 868-872
Author(s):  
Qiang Wu ◽  
Yong Tang ◽  
Yong Qiang Yang ◽  
Yu Zhong Li
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Finite Difference ◽  
Difference Equation ◽  
Laser Welding ◽  
Stable State ◽  
High Strength ◽  
Control Mode ◽  
Finite Difference Equation ◽  
Technological Parameters

Based on quasi-stable state heat-transfer control mode, finite difference equation of thermal conductivity in laser welding is deduced. Physical parameter (specific heat) substitutes for phase-changing latent heat, then critical temperature of thermal conductivity welding is determined, so finite difference equation can be solved by MATLAB software. Temperature field distribution is simulated to weldment.Influence of technological parameters such as laser power and welding speed on temperature field are investigated systematically by numerical simulation, these can establish theoretical basis for optimization of technological parameters in laser welding.

scholarly journals OCT Capillary Depth Measurement in Copper Micro Welding Using Green Lasers

2021 ◽  
Vol 11 (6) ◽  
pp. 2655
Author(s):  
Tobias Beck ◽  
Christoph Bantel ◽  
Meiko Boley ◽  
Jean Pierre Bergmann
Keyword(s):  
Laser Welding ◽  
Process Monitoring ◽  
Weld Seam ◽  
Welding Process ◽  
Direct Determination ◽  
Deep Penetration ◽  
Scanning System ◽  
Depth Measurement ◽  
Aspect Ratios ◽  
Deep Penetration Welding

The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions and short process times, reliable in-line process monitoring has proven to be difficult. By using a green laser with a wavelength of λ=515, the welding process of copper benefits from an increased absorption, resulting in a shallow and stable deep penetration welding process. This opens up new possibilities for the process monitoring. In this contribution, the monitoring of the capillary depth in micro copper welding, with welding depth of up to 1 , was performed coaxially using an optical coherence tomography (OCT) system. By comparing the measured capillary depth and the actual welding depth, a good correlation between two measured values could be shown independently of the investigated process parameters and stability. Measuring the capillary depth allows a direct determination of the present aspect ratio in the welding process. For deep penetration welding, aspect ratios as low as 0.35 could be shown. By using an additional scanning system to superimpose the welding motion with a spacial oscillating of the OCT beam perpendicular to the welding motion, multiple information about the process could be determined. Using this method, several process information can be measured simultaneously and is shown for the weld seam width exemplarily.

Analysis of Characteristics of Mg Alloy Welded Joint by Laser Welding

2011 ◽  
Vol 314-316 ◽  
pp. 949-952
Author(s):  
Hong Jian Xiu ◽  
Jun Liu ◽  
Jun Hui Dong ◽  
Ping Xu
Keyword(s):  
Heat Conduction ◽  
Laser Welding ◽  
Weld Metal ◽  
Welding Speed ◽  
Heat Input ◽  
Welded Joint ◽  
Mg Alloy ◽  
Deep Penetration ◽  
Deep Penetration Welding ◽  
Main Factor

The microstructure, the regular and mechanism of various parameters on formation of weld bead of Mg alloy AMCa403 using a laser welding were investigated. The results show that sound welds without major defects can be produced. Two welding modes of deep penetration welding, heat conduction welding were found, and heat input was found to be the main factor for welding mode and shape. The microstructure of weld metal is significantly finer than the base metal. At the same power, with the increase of welding speed, the microstructure of weld metal is much finer.

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