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Laser Materials Fabrication and Joining

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (31 March 2020) | Viewed by 53589

Special Issue Editor

Prof. Dr. Giuseppe Casalino

E-Mail Website1 Website2
Guest Editor
Department of Mechanics Mathematics Management, Polytechnic University of Bari, 70125 Bari, Italy
Interests: advanced manufacturing; welding and joining; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The use of lasers in manufacturing has increased dramatically over recent years, leading to a position in the processing of old and innovative materials. This Special Issue on “Laser Materials Fabrication and Joining” aims to provide a revised, updated and expanded overview of processes and applications of industrial lasers in materials processing. Innovative aspects of laser techniques and process, such as joining, hybrid welding, materials deposition, additive, coating, etc., will be included.

In desired papers, metallic and non-metallic materials will be treated, as well as dissimilar and functional materials. Essential and recent laser sources and systems are presented along with their high-power and high-precision applications in advanced manufacturing.

The subjects of the papers cover fundamental theory, technology and methods, traditional and emerging applications and potential future directions. Mathematical modeling, simulation, optimization and control of those laser processes and resulting material properties are also welcomed.

The wishes for this Special Issue are to raise the scientific and technical know-how for laser materials interactions to improve their competitiveness and diffusion as a fabrication technology.

Prof. Giuseppe Casalino
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Laser materials processing
  • joining
  • additive
  • coating
  • metal alloys
  • composites
  • plastics
  • hybrid processes
  • modeling
  • simulation
  • optimization
  • control

Published Papers (15 papers)

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Research

14 pages, 5662 KiB  
Article
Thermo-Mechanical Simulation of Hybrid Welding of DP/AISI 316 and TWIP/AISI 316 Dissimilar Weld
by Patrizia Perulli, Michele Dassisti and Giuseppe Casalino
Materials 2020, 13(9), 2088; https://doi.org/10.3390/ma13092088 - 01 May 2020
Cited by 9 | Viewed by 2550
Abstract
In this paper, hybrid laser-MAG (metal active gas) welding of twinning-induced plasticity (TWIP) and dual-phase (DP) steels with austenitic stainless steel (AISI316) was simulated by means of the finite element method. A thermo-mechanical model, which uses a 3D heat sources, was developed using [...] Read more.
In this paper, hybrid laser-MAG (metal active gas) welding of twinning-induced plasticity (TWIP) and dual-phase (DP) steels with austenitic stainless steel (AISI316) was simulated by means of the finite element method. A thermo-mechanical model, which uses a 3D heat sources, was developed using the software Simufact Welding. The calculated dimensions, shape and distortion of the weld were compared with the experimental results, thence the model was validated. The metallurgical transformations for the DP steel were evaluated using the continuous cooling transformation (CCT) diagram and the calculated cooling rate. The numerical model predicted accurately the shape of the molten pool, the thermal cycles as well as the geometrical distortion of the butt weld. Therefore, the numerical model showed a good reliability and its potential for further development. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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11 pages, 3578 KiB  
Article
High-Efficiency and Low-Damage Lapping Process Optimization
by Ci Song, Feng Shi, Wanli Zhang, Zhifan Lin and Yuxuan Lin
Materials 2020, 13(3), 569; https://doi.org/10.3390/ma13030569 - 24 Jan 2020
Cited by 6 | Viewed by 2604
Abstract
The silica opticsare widely applied in the modern laser system, and its fabrication is always the research focus. In the manufacturing process, the lapping process occurs between grinding and final polishing. However, lapping processes optimizations focus on decreasing the depth of sub-surface damage [...] Read more.
The silica opticsare widely applied in the modern laser system, and its fabrication is always the research focus. In the manufacturing process, the lapping process occurs between grinding and final polishing. However, lapping processes optimizations focus on decreasing the depth of sub-surface damage (SSD) or improving lapping efficiency individually. So, the optimum balance point between efficiency and damageshould be studied further. This manuscript establishes the effective removal rate of damage (ERRD)model, and the relationship between the ERRD and processing parameters is simulated. Then, high-efficiency, low-damage lapping processing routine is established based on the simulation. The correctness and feasibility are validated. In this work, the optimized method is confirmed that it can improve efficiency and decrease damage layer depth in the lapping process which promotes the development of optics in low-damage fabrication. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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12 pages, 3691 KiB  
Article
On the Relevance of Volumetric Energy Density in the Investigation of Inconel 718 Laser Powder Bed Fusion
by Fabrizia Caiazzo, Vittorio Alfieri and Giuseppe Casalino
Materials 2020, 13(3), 538; https://doi.org/10.3390/ma13030538 - 23 Jan 2020
Cited by 68 | Viewed by 3751
Abstract
Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper [...] Read more.
Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper aims at investigating the relevance of the volumetric energy density (VED) that is a concise index of some governing factors with a potential operational use. This paper proves the fact that the observed experimental variation in the surface roughness, number and size of pores, the fractional density, and Vickers hardness can be explained in terms of VED that can help the investigator in dealing with several process parameters at once. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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19 pages, 8885 KiB  
Article
Experimental and Numerical Study of AISI 4130 Steel Surface Hardening by Pulsed Nd:YAG Laser
by Giuseppe Casalino, Mahmoud Moradi, Mojtaba Karami Moghadam, Ali Khorram and Patrizia Perulli
Materials 2019, 12(19), 3136; https://doi.org/10.3390/ma12193136 - 26 Sep 2019
Cited by 30 | Viewed by 4166
Abstract
Laser surface transformation hardening (LSTH) of AISI 4130 was investigated by a Nd:YAG pulsed laser. Laser focal height (LFH), pulse width (LPW), scanning speed (LSS), and power (LP) varied during the experiments. The microstructure of the treated zone was characterized by optical (OM) [...] Read more.
Laser surface transformation hardening (LSTH) of AISI 4130 was investigated by a Nd:YAG pulsed laser. Laser focal height (LFH), pulse width (LPW), scanning speed (LSS), and power (LP) varied during the experiments. The microstructure of the treated zone was characterized by optical (OM) and field emission scanning electron microscopy (FESEM). Micro-hardness was measured in the width and depth directions. Results showed that the hardness and depth of hardened layer increased by decreasing the LSS and the laser focal position (LFP), and by increasing the LPW. The results were compared with those obtained by furnace heat treatment of the same steel. Eventually, a finite element model was employed for the simulation of the LSTH of AISI 4130 steel and calculation of the heat-treated zone. The results showed that the model can predict with accuracy the temperature profile and the size and the shape of the laser hardened region. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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12 pages, 4701 KiB  
Article
Printability and Microstructure of Selective Laser Melting of WC/Co/Cr Powder
by Sabina Luisa Campanelli, Nicola Contuzzi, Paolo Posa and Andrea Angelastro
Materials 2019, 12(15), 2397; https://doi.org/10.3390/ma12152397 - 27 Jul 2019
Cited by 45 | Viewed by 3318
Abstract
The selective laser melting process is a growing technology for the manufacture of parts with very complex geometry. However, not all materials are suitable for this process, involving rapid localized melting and solidification. Tungsten has difficulties due to the high melting temperature. This [...] Read more.
The selective laser melting process is a growing technology for the manufacture of parts with very complex geometry. However, not all materials are suitable for this process, involving rapid localized melting and solidification. Tungsten has difficulties due to the high melting temperature. This study focuses on the possibility of processing a WC/Co/Cr composite powder using selective laser melting. Samples were fabricated and characterized in terms of density, defects, microstructure and hardness. Tests were conducted with hatch spacing of 120 μm and process speed of 40 mm/s. A constant laser power of 100 W and a powder layer thickness of 30 μm were used. A relative density of 97.53%, and therefore a low porosity, was obtained at an energy density of 12.5 J/mm2. Microscopic examination revealed the presence of small cracks and a very heterogeneous distribution of the grain size. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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Graphical abstract

13 pages, 9943 KiB  
Article
Mechanical Properties and Microstructures of Laser–TIG Welded ME21 Rare Earth Mg Alloy
by Taotao Li, Gang Song, Zhaodong Zhang and Liming Liu
Materials 2019, 12(13), 2188; https://doi.org/10.3390/ma12132188 - 08 Jul 2019
Cited by 8 | Viewed by 2827
Abstract
The microstructural and mechanical properties of laser–tungsten inert gas (TIG) hybrid welding of Mg alloy sheets for automobiles are investigated in the present work, including AZ31 and ME21, AZ31 and AZ31, ME21 and ME21, and corresponding comparisons were carried out. The results show [...] Read more.
The microstructural and mechanical properties of laser–tungsten inert gas (TIG) hybrid welding of Mg alloy sheets for automobiles are investigated in the present work, including AZ31 and ME21, AZ31 and AZ31, ME21 and ME21, and corresponding comparisons were carried out. The results show that columnar crystals appear in the ME21/ME21 and ME21/AZ31 heat-affected zones, and no columnar crystals formed in the AZ31/AZ31 fusion zone under a constant heat ratio of arc to laser. Heat accumulation in a narrow area and the undercooling degree are the two main factors for the formation of columnar crystal. The ME21/ME21 joint has a tensile strength of up to 185.2 MPa, which is about 81.8% of that of the ME21 base metal (BM-ME21). The tensile strength of the ME21/AZ31 joint (158.8 MPa) is lower than that of the ME21/ME21 joint. The fracture of the ME21/ME21 and ME21/AZ31 joints occurs at the junction of the columnar crystal and the heat-affected zone. The microhardness of the ME21/AZ31 joint presents a low–high–low–high trend from BE-ME21 to BE-AZ31, and the distribution of the ME21/AZ31 welded joint microhardness in the cross-section presents a low–high–low trend. The ME21/ME21 weld seam is composed of an AlCe3 intermetallic compound, Mn particles, and α-Mg, and the ME21/AZ31 weld seam is composed of a α-Mg, Mg17Al12, and AlCe3 intermetallic compound. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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22 pages, 8734 KiB  
Article
Simulation of Laser-assisted Directed Energy Deposition of Aluminum Powder: Prediction of Geometry and Temperature Evolution
by Fabrizia Caiazzo and Vittorio Alfieri
Materials 2019, 12(13), 2100; https://doi.org/10.3390/ma12132100 - 29 Jun 2019
Cited by 30 | Viewed by 5201
Abstract
One of the main current challenges in the field of additive manufacturing and directed energy deposition of metals, is the need for simulation tools to prevent or reduce the need to adopt a trial-and-error approach to find the optimum processing conditions. A valuable [...] Read more.
One of the main current challenges in the field of additive manufacturing and directed energy deposition of metals, is the need for simulation tools to prevent or reduce the need to adopt a trial-and-error approach to find the optimum processing conditions. A valuable help is offered by numerical simulation, although setting-up and validating a reliable model is challenging, due to many issues related to the laser source, the interaction with the feeding metal, the evolution of the material properties and the boundary conditions. Indeed, many attempts have been reported in the literature, although some issues are usually simplified or neglected. Therefore, this paper is aimed at building a comprehensive numerical model for the process of laser-assisted deposition. Namely: the geometry of the deposited metal is investigated in advance and the most effective reference shape is found to feed the simulation as a function of the governing factors for single- and multi-track, multi-layer deposition; then, a non-stationary thermal model is proposed and the underlying hypotheses to simulate the addition of metal are discussed step-by-step. Validation is eventually conducted, based on experimental evidence. Aluminum alloy 2024 is chosen as feeding metal and substrate. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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16 pages, 8267 KiB  
Article
An Investigation into Picosecond Laser Micro-Trepanning of Alumina Ceramics Employing a Semi-Water-Immersed Scheme
by Qiang Ma, Hao Zhu, Zhaoyang Zhang, Kun Xu, Xueren Dai, Shuaijie Zhu and Anbin Wang
Materials 2019, 12(11), 1812; https://doi.org/10.3390/ma12111812 - 04 Jun 2019
Cited by 11 | Viewed by 3108
Abstract
Intense interest has been given to the fabrication of micro-through-holes with smaller tapering and higher aspect ratios in engineering ceramics due to their wide range of applications in MEMS and aerospace. A semi-water-immersed laser micro-trepanning (SWILT) scheme is proposed and investigated in this [...] Read more.
Intense interest has been given to the fabrication of micro-through-holes with smaller tapering and higher aspect ratios in engineering ceramics due to their wide range of applications in MEMS and aerospace. A semi-water-immersed laser micro-trepanning (SWILT) scheme is proposed and investigated in this paper with alumina ceramics as the target material, and its performance is assessed and compared with the direct laser trepanning method. Relevant processing parameters influencing the trepanning process are explored through an orthogonally designed experiment, and their effects on hole profiles are adequately discussed to yield optimized parameters. It is revealed that SWILT is capable of producing micro-through-holes with minimized hole tapering and much straighter sidewalls compared with the direct trepanning results, whereas the ablated surface quality is relatively rougher. The micro-through-hole formation mechanisms are also amply analyzed, where the transition hole development may be purely attributed to the laser-material interaction in the direct laser trepanning condition, while the SWILT case features an enhanced material-removal rate, especially at the lower part of the through-hole. The latter is due to the strengthened mechanical effects coming from the water-confined plasma zone and the following cavitation bubble collapse, which may efficiently expel the molten material from sidewalls and result in significantly reduced hole tapering. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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14 pages, 3327 KiB  
Article
Thermal Efficiency Analysis for Laser-Assisted Plasma Arc Welding of AISI 304 Stainless Steel
by Dominik Hipp, Achim Mahrle, Eckhard Beyer, Sebastian Jäckel, Martin Hertel and Uwe Füssel
Materials 2019, 12(9), 1460; https://doi.org/10.3390/ma12091460 - 06 May 2019
Cited by 15 | Viewed by 3366
Abstract
Synergistic effects during hybrid laser-arc welding may cause increased process efficiencies. However, the basic interactions behind these effects are still being discussed, with some contradictory reports. In this study, particular welding parameters of interest were systematically varied to further the understanding of involved [...] Read more.
Synergistic effects during hybrid laser-arc welding may cause increased process efficiencies. However, the basic interactions behind these effects are still being discussed, with some contradictory reports. In this study, particular welding parameters of interest were systematically varied to further the understanding of involved phenomena. The experimental trials are evaluated regarding their synergistic achievements in terms of process efficiency, melting efficiency and energy coupling efficiency using a factorial two-level Design-of-Experiment (DoE) approach. The results show that the growth in process efficiency can be attributed to a dramatic increase in melting efficiency whereas the energy coupling efficiency is only moderately increased. Thus, the synergistic effect is mainly caused by secondary mechanisms that change the energy usage inside the workpiece while direct interactions between the two heat sources can be excluded as a reasonable cause for increased process efficiencies. It is concluded that the different sizes of the heat sources change the heat and mass flow positively and consequently lead to a higher performance level. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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17 pages, 7663 KiB  
Article
Laser-Assisted Synthesis of Cu-Al-Ni Shape Memory Alloys: Effect of Inert Gas Pressure and Ni Content
by Stefan Niedbalski, Alicia Durán, Magdalena Walczak and Jorge A. Ramos-Grez
Materials 2019, 12(5), 794; https://doi.org/10.3390/ma12050794 - 07 Mar 2019
Cited by 14 | Viewed by 3620
Abstract
The paper explores the applicability of laser-assisted synthesis for producing high density Cu-Al-Ni alloys with shape memory characteristics, that could be further developed towards a method of additive manufacturing of large size Cu-based shape memory alloys (SMA). The manufacturing approach consists in laser [...] Read more.
The paper explores the applicability of laser-assisted synthesis for producing high density Cu-Al-Ni alloys with shape memory characteristics, that could be further developed towards a method of additive manufacturing of large size Cu-based shape memory alloys (SMA). The manufacturing approach consists in laser melting of elemental powder mixture in a controlled atmosphere of varying relative pressure of protective argon gas, producing alloys of 14.2 wt.% Al and Ni content varying between 2 and 4 wt.%. All the fabricated alloys are found to have attained martensitic microstructures capable of SMA specific phase transformations in the temperature range from 85 to 192 °C. Both gas pressure and content of Ni are found to affect the specific transformation temperatures, transformation enthalpies, and mechanical properties. In particular, increasing gas pressure suppresses the austenite to martensite transformation reducing microhardness. In conclusion, the selective laser melting (SLM) employed in this work is shown capable of producing high density Cu-Al-Ni SMA (porosity ≈ 2%). Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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21 pages, 7182 KiB  
Article
Performance Evaluation and Comparison between Direct and Chemical-Assisted Picosecond Laser Micro-Trepanning of Single Crystalline Silicon
by Hao Zhu, Zhaoyang Zhang, Kun Xu, Jinlei Xu, Shuaijie Zhu, Anbin Wang and Huan Qi
Materials 2019, 12(1), 41; https://doi.org/10.3390/ma12010041 - 23 Dec 2018
Cited by 14 | Viewed by 3663
Abstract
The fabrication of micro-holes in silicon substrates that have a proper taper, higher depth-to-diameter ratio, and better surface quality has been attracting intense interest for a long time due to its importance in the semiconductor and MEMS (Micro-Electro-Mechanical System) industry. In this paper, [...] Read more.
The fabrication of micro-holes in silicon substrates that have a proper taper, higher depth-to-diameter ratio, and better surface quality has been attracting intense interest for a long time due to its importance in the semiconductor and MEMS (Micro-Electro-Mechanical System) industry. In this paper, an experimental investigation of the machining performance of the direct and chemical-assisted picosecond laser trepanning of single crystalline silicon is conducted, with a view to assess the two machining methods. The relevant parameters affecting the trepanning process are considered, employing the orthogonal experimental design scheme. It is found that the direct laser trepanning results are associated with evident thermal defects, while the chemical-assisted method is capable of machining micro-holes with negligible thermal damage. Range analysis is then carried out, and the effects of the processing parameters on the hole characteristics are amply discussed to obtain the recommended parameters. Finally, the material removal mechanisms that are involved in the two machining methods are adequately analyzed. For the chemical-assisted trepanning case, the enhanced material removal rate may be attributed to the serious mechanical effects caused by the liquid-confined plasma and cavitation bubbles, and the chemical etching effect provided by NaOH solution. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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16 pages, 11844 KiB  
Article
Off-Set and Focus Effects on Grade 5 Titanium to 6061 Aluminum Alloy Fiber Laser Weld
by Giuseppe Casalino, Sonia D’Ostuni, Pasquale Guglielmi, Paola Leo, Gianfranco Palumbo and Antonio Piccininni
Materials 2018, 11(11), 2337; https://doi.org/10.3390/ma11112337 - 21 Nov 2018
Cited by 13 | Viewed by 3522
Abstract
Joining dissimilar metal alloys together has become a major issue in the welding industry since the rapid development of innovative and performing multi-materials products. In case, titanium and Aluminum alloys can be laser-welded using a placement of the laser beam aside the weld [...] Read more.
Joining dissimilar metal alloys together has become a major issue in the welding industry since the rapid development of innovative and performing multi-materials products. In case, titanium and Aluminum alloys can be laser-welded using a placement of the laser beam aside the weld centerline, which is called off-set. The fused zone is deep and narrow and the reaction between titanium and Aluminum is limited to a thin interlayer, which improves mechanical properties. In this paper, the effect of focus and off-set distance of the laser beam on the weldability of grade 5 titanium to 6061 Aluminum alloy dissimilar butt weld are presented. The interlayer thickness was correlated to the process parameters and tensile behavior of the weld. The map of deformation showed different deformations of the two weld sides. The data coming from the metallurgical and mechanical characterization of the weld were analyzed to figure out the best off-set and focus combination in the range studied. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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12 pages, 2330 KiB  
Article
Composite Bonding Pre-Treatment with Laser Radiation of 3 µm Wavelength: Comparison with Conventional Laser Sources
by David Blass, Sebastian Nyga, Bernd Jungbluth, Hans-Dieter Hoffmann and Klaus Dilger
Materials 2018, 11(7), 1216; https://doi.org/10.3390/ma11071216 - 16 Jul 2018
Cited by 11 | Viewed by 3525
Abstract
To use the full potential of composite parts, e.g., to reduce the structural weight of cars or airplanes, a greater focus is needed on the joining technology. Adhesive bonding is considered favorable, superior joining technology for these parts. Unfortunately, to provide a structural [...] Read more.
To use the full potential of composite parts, e.g., to reduce the structural weight of cars or airplanes, a greater focus is needed on the joining technology. Adhesive bonding is considered favorable, superior joining technology for these parts. Unfortunately, to provide a structural and durable bond, a surface pre-treatment is necessary. Due to its high integration potential in industrial process chains, laser radiation can be a very efficient tool for this purpose. Within the BMBF-funded (German Federal Ministry of Education and Research) project GEWOL, a laser source that emits radiation at 3 µm wavelength (which shows significant advantages in theory) was developed for a sensitive laser-based bonding pre-treatment. Within the presented study, the developed laser source was compared with conventional laser sources emitting radiation at 355 nm, 1064 nm, and 10,600 nm in terms of application for a composite bonding pre-treatment. With the different laser sources, composites were treated, analytically tested, subsequently bonded, and mechanically tested to determine the bonding ability of the treated specimens. The results show a sensitive treatment of the surface with the developed laser source, which resulted in a very effective cleaning, high bonding strengths (over 32 MPa), and a good effectiveness compared with the conventional laser sources. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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16 pages, 6756 KiB  
Article
Assessment of the Weldability of T-Welded Joints in 10 mm Thick TMCP Steel Using Laser Beam
by Jacek Górka
Materials 2018, 11(7), 1192; https://doi.org/10.3390/ma11071192 - 11 Jul 2018
Cited by 19 | Viewed by 3612
Abstract
The article presents tests aimed to verify the possibility of Thermomechanically Controlled Processed (TMCP) steels T-joints laser welding. The 10 mm thick high-yield-point steel S700MC obtained in an industrial manufacturing process was used for tests of laser welding. The joints made during the [...] Read more.
The article presents tests aimed to verify the possibility of Thermomechanically Controlled Processed (TMCP) steels T-joints laser welding. The 10 mm thick high-yield-point steel S700MC obtained in an industrial manufacturing process was used for tests of laser welding. The joints made during the tests were single- and double-sided. Subsequent nondestructive tests revealed that the laser-welded joints represented quality level B in accordance with PN-EN ISO 13919-1. Single-sided welding performed at the output laser beam power of 11 kW provided the penetration depth of just 8 mm without visibly deforming of the joint. The double-sided welded joints were characterized by proper geometry and the presence of gas pores in the welds not compromising the requirements of quality level B (strict requirements). The identified weld structure was bainitic-ferritic. The weld hardness was by approximately 60 HV1 higher than that of the base material (280 HV1). The HAZ (Heat Affected Zone) area was slightly softer than the base material. The tests of thin foils performed using a high-resolution scanning transmission electron microscope revealed that, during welding, an increase in the content of the base material in the weld was accompanied by an increase in contents of alloying microagents Ti and Nb, particularly near the fusion line. The above-named alloying microagents, in the form of fine-dispersive (Ti,Nb)(C,N) type precipitates, could reduce plastic properties of joints. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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15 pages, 5591 KiB  
Article
Tensile Property of ANSI 304 Stainless Steel Weldments Subjected to Cavitation Erosion Based on Treatment of Laser Shock Processing
by Lei Zhang, Yue-Hua Liu, Kai-Yu Luo, Yong-Kang Zhang, Yong Zhao, Jian-Yun Huang, Xu-Dong Wu and Chuang Zhou
Materials 2018, 11(5), 805; https://doi.org/10.3390/ma11050805 - 16 May 2018
Cited by 9 | Viewed by 3746
Abstract
Tensile property was one important index of mechanical properties of ANSI 304 stainless steel laser weldments subjected to cavitation erosion (CE). Laser shock processing (LSP) was utilized to strengthen the CE resistance, and the tensile property and fracture morphology were analyzed through three [...] Read more.
Tensile property was one important index of mechanical properties of ANSI 304 stainless steel laser weldments subjected to cavitation erosion (CE). Laser shock processing (LSP) was utilized to strengthen the CE resistance, and the tensile property and fracture morphology were analyzed through three replicated experiment times. Results showed tensile process of treated weldments was composed of elastic deformation, plastic deformation, and fracture. The elastic limit, elastic modulus, elongation, area reduction, and ultimate tensile strength of tensile sample after CE were higher in view of LSP. In the fracture surface, the fiber zone, radiation zone and shear lip zone were generated, and those were more obvious through LSP. The number and size of pores in the fracture surface were smaller, and the fracture surface was smoother and more uniform. The dimples were elongated along the unified direction due to effects of LSP, and the elongated direction was in agreement with the crack propagation direction. Their distribution and shape were uniform with deeper depth. It could be reflected that the tensile property was improved by LSP and the CE resistance was also enhanced. Full article
(This article belongs to the Special Issue Laser Materials Fabrication and Joining)
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