Evaluation of optical radiation of laser welding processes

Abstract To avoid the formation of Ti-Ni intermetallics in a joint, three laser welding processes for Ti alloy–NiTi alloy joints were introduced. Sample A was formed while a laser acted at the Ti alloy–NiTi alloy interface, and the joint fractured along the weld centre line immediately after welding without filler metal. Sample B was formed while the laser acted on a Cu interlayer. The average tensile strength of sample B was 216 MPa. Sample C was formed while the laser acted 1.2 mm on the Ti alloy side. The one-pass welding process involved the creation of a joint with one fusion weld and one diffusion weld separated by the remaining unmelted Ti alloy. The mechanical performance of sample C was determined by the diffusion weld formed at the Ti alloy–NiTi alloy interface with a tensile strength of 256 MPa.

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Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle

MATEC Web of Conferences ◽

10.1051/matecconf/202032608005 ◽

2020 ◽

Vol 326 ◽

pp. 08005

Author(s):

Mete Demirorer ◽

Wojciech Suder ◽

Supriyo Ganguly ◽

Simon Hogg ◽

Hassam Naeem

Keyword(s):

Laser Beam ◽

Laser Welding ◽

Heat Input ◽

Thermal Cycle ◽

Laser Beam Welding ◽

Base Material ◽

High Strength ◽

Cooling Rates ◽

Aa 2024 ◽

Welding Processes

An innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic cooling.

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Penetration depth estimation for monitoring CO2 laser welding processes

International Congress on Applications of Lasers & Electro-Optics ◽

10.2351/1.5058957 ◽

1995 ◽

Cited By ~ 2

Author(s):

Kishore Lankalapalli ◽

Jay F. Tu

Keyword(s):

Laser Welding ◽

Penetration Depth ◽

Co2 Laser ◽

Depth Estimation ◽

Welding Processes

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Determination of Heat Input in Tungsten Inert Gas and Laser Welding of Type Optim 960 QC Structural Steel Using Adams’ Equation for 2-D Heat Distribution

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.750.45 ◽

2017 ◽

Vol 750 ◽

pp. 45-52

Author(s):

Sveto Cvetkovski

Keyword(s):

Laser Welding ◽

Heat Input ◽

Arc Welding ◽

Research Work ◽

Laser Beam Welding ◽

Peak Temperature ◽

Efficiency Coefficient ◽

Zone Recrystallization ◽

Welding Processes

The heat input during conventional arc welding processes can be readily calculated knowing the power taken from the power source. The efficiency coefficient can be taken from the appropriate literature standards. Here, the intention of the performed research work was to develop a procedure for determination of heat input in arc and laser welding processes implementing Adams equation - modified Rykalin equation for two dimensional heat distributions (2-D). To realize this idea, it is necessary to determine two characteristic temperatures points in the HAZ with known peak temperature, and to determine distance between them. Implementing measured values for distance in Adams’ equation, heat input in arc welding can be directly determined in arc welded joints.In laser beam welding, the absorption of the beam in the metal is not known, so that the welding heat input cannot be calculated directly, and direct implementation of Adam’s equation is not possible i.e. absorption coefficient has to be determined first, and after that calculation of heat input is possible.The peak temperatures corresponding to specific microstructures can be obtained by performing welding simulation, by the Gleeble 1500 simulator in our case. As one of the peak temperatures, the melting temperature can be used corresponding to the fusion line, so that at least one characteristic peak temperature such as coarse grain zone, fine grin zone, intercritical zone, recrystallization, has to be determined by the simulation.Performed research showed that obtained values for heat input using Adam’s equation correspond pretty well with standard equation for heat input in arc welding.

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Advances in joining technologies for the innovation of 21st century lightweight aluminium-CFRP hybrid structures

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211073027 ◽

2022 ◽

pp. 095440892110730

Author(s):

Renangi Sandeep ◽

Arivazhagan Natarajan

Keyword(s):

Shear Strength ◽

Laser Welding ◽

Heat Input ◽

Mechanical Performance ◽

Current Knowledge ◽

Ultrasonic Welding ◽

Hybrid Structures ◽

Joint Shear Strength ◽

Hybrid Joints ◽

Welding Processes

In the twenty-first century, the application of carbon fiber reinforced polymer (CFRP) materials in the vehicle industry are growing rapidly due to lightweight, high specific strength, and elasticity. In the automobile and aerospace industries, CFRP needs to be joined with metals to build complete structures. The demand for hybrid structures has prompted research into the combination of CFRP and metals in manufacturing. Aluminium and CFRP structures combine the mechanical properties of aluminium with the superior physical and chemical properties of CFRP. However, joining dissimilar materials is often challenging to achieve. Various joining technologies are developed to produce hybrid joints of CFRP, and aluminium alloys include conventional adhesives, mechanical and thermal joining technologies. In this review article, an extensive review was carried out on the thermal joining technologies include laser welding, friction-based welding technologies, ultrasonic welding, and induction welding processes. The article primarily focused on the current knowledge and process development of these technologies in fabricating dissimilar aluminium and CFRP structures. Besides, according to Industry 4.0 requirements, additive manufacturing-based techniques to fabricate hybrid structures are presented. Finally, this article also addressed the various improvements for the future development of these joining technologies. Ultrasonic welding yields the maximum shear strength among the various hybrid joining technologies due to lower heat input. On the other hand, laser welding produces higher heat input, which deteriorates the mechanical performance of the hybrid joints. Surface pretreatments on material surfaces prior to joining showed a significant effect on joint shear strength. Surface modification using anodizing is considered an optimal method to improve wettability, increasing mechanical interlocking phenomena.

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