Hardness, grainsize and porosity formation prediction on the Laser Metal Deposition of AISI 304 stainless steel

The presented numerical model solves the heat and mass transfer equations in the Laser Metal Deposition process and based on the evolution of the thermal field predicts the grainsize, the resulting hardness and evaluates the pores formation probability in an AISI 304 stainless steel. For this purpose, in a first step, the model calculates the shape of the deposited material and the variations of the temperature field. In a second step, and based on the evolution of the thermal field, the model calculates the resulting hardness of the deposited material, the grainsize and the porosity formation probability after the deposition process. Numerical results are experimentally validated, and good agreement is obtained. Consequently, besides predicting the geometry of the resulting part and the evolution of the thermal field, the developed model enables to evaluate the quality of the deposited material. Therefore, the optimum process conditions and strategy when depositing AISI 304 stainless steel can be determined without initial trial-and-error tests.“LaCaixa” foundation . In addition, this work has been founded by the H2020- FoF13-2016 PARADDISE project (contract No.: 723440). This work has been also carried out in the framework of the DPI2016-79889-R – INTEGRADDI project, funded by the Spanish Ministry of Industry and Competitiveness

Laser polishing and structuring by laser remelting of 1.2379+

The objective of this project is the development of laser polishing (micro laser polishing with pulsed laser radiation and macro laser polishing using cw laser radiation) and laser structuring by remelting process for 1.2379+ as well as the characterization of the produced surfaces via white light interferometry, tactile roughness measurements and spectral roughness analysis. The aim is not exclusively the development of parameters that lead to the smallest roughness or highest structures, but to analyze which wavelengths of the roughness spectrum are influenced by which process and corresponding process parameters

Latest Developments in Industrial Hybrid Machine Tools that Combine Additive and Subtractive Operations

Hybrid machine tools combining additive and subtractive processes have arisen as a solution to increasing manufacture requirements, boosting the potentials of both technologies, while compensating and minimizing their limitations. Nevertheless, the idea of hybrid machines is relatively new and there is a notable lack of knowledge about the implications arisen from their in-practice use. Therefore, the main goal of the present paper is to fill the existing gap, giving an insight into the current advancements and pending tasks of hybrid machines both from an academic and industrial perspective. To that end, the technical-economical potentials and challenges emerging from their use are identified and critically discussed. In addition, the current situation and future perspectives of hybrid machines from the point of view of process planning, monitoring, and inspection are analyzed. On the one hand, it is found that hybrid machines enable a more efficient use of the resources available, as well as the production of previously unattainable complex parts. On the other hand, it is concluded that there are still some technological challenges derived from the interaction of additive and subtractive processes to be overcome (e.g., process planning, decision planning, use of cutting fluids, and need for a post-processing) before a full implantation of hybrid machines is fulfilledSpecial thanks are addressed to the Industry and Competitiveness Spanish Ministry for the support on the DPI2016-79889-R INTEGRADDI project and to the PARADDISE project H2020-IND-CE-2016-17/H2020-FOF-2016 of the European Union's Horizon 2020 research and innovation program

Analysis of the Influence of the Use of Cutting Fluid in Hybrid Processes of Machining and Laser Metal Deposition (LMD)

Hybrid manufacturing processes that combine additive and machining operations are gaining relevance in modern industry thanks to the capability of building complex parts with minimal material and, many times, with process time reduction. Besides, as the additive and subtractive operations are carried out in the same machine, without moving the part, dead times are reduced and higher accuracies are achieved. However, it is not clear whether the direct material deposition after the machining operation is possible or intermediate cleaning stages are required because of the possible presence of residual cutting fluids. Therefore, different Laser Metal Deposition (LMD) tests are performed on a part impregnated with cutting fluid, both directly and after the removal of the coolant by techniques such as laser vaporizing and air blasting. The present work studies the influence of the cutting fluid in the LMD process and the quality of the resulting part. Resulting porosity is evaluated and it is concluded that if the part surface is not properly clean after the machining operation, deficient clad quality can be obtained in the subsequent laser additive operation.This study was supported by the H2020 FoF13 PARADDISE Project (Grant Agreement No. 723440)

Functionally Graded AISI 316L and AISI H13 Manufactured by L-DED for Die and Mould Applications

Tooling in the die and mould industry is subjected to high-wear and high-temperature environments, which often leads to the premature failure of this high-added-value tooling. When severe damage occurs, an alternative to replacing the whole component consists of the repair by laser-directed energy deposition (L-DED). For that end, intermediate layers are commonly employed as buffer material, where introducing a functionally graded material (FGM) might be beneficial to avoid material incompatibilities and improve the overall performance of the tooling. In the present work, an FGM composed of gradient AISI 316L to AISI H13 has been manufactured, and its microstructure and hardness analysed. Firstly, cracking owing to the formation of brittle intermediate phases has been detected. Secondly, an increase of the hardness and a decrease of the corrosion resistance has been observed when transitioning from AISI 316L to AISI H13. Thirdly, despite the FGM composition evolving linearly, nonlinear material properties such as hardness and corrosion have been observed, which are conditioned by the microstructure formed during the L‑DED process and the nonlinear influence of the composition of steel on such properties. Consequently, nonlinear compositional gradients are recommended if linear mechanical properties are to be obtained in the case of steel FGMs.This research was funded by the Basque Government (Eusko Jaurlaritza) under the ELKARTEK Program, QUALYFAM project, grant number KK-2020/00042 and Spanish Ministry of Industry and Competitiveness under the PID2019-109220RB-I00 ALASURF project

Study of the Influence of Shielding Gases on Laser Metal Deposition of Inconel 718 Superalloy

The use of the Laser Metal Deposition (LMD) technology as a manufacturing and repairing technique in industrial sectors like the die and mold and aerospace is increasing within the last decades. Research carried out in the field of LMD process situates argon as the most usual inert gas, followed by nitrogen. Some leading companies have started to use helium and argon as carrier and shielding gas, respectively. There is therefore a pressing need to know how the use of different gases may affect the LMD process due there being a lack of knowledge with regard to gas mixtures. The aim of the present work is to evaluate the influence of a mixture of argon and helium on the LMD process by analyzing single tracks of deposited material. For this purpose, special attention is paid to the melt pool temperature, as well as to the characterization of the deposited clads. The increment of helium concentration in the gases of the LMD processes based on argon will have three effects. The first one is a slight reduction of the height of the clads. Second, an increase of the temperature of the melt pool. Last, smaller wet angles are obtained for higher helium concentrations.This work was supported by the DPI 2016-79889-R INTEGRAddi Project and the POCTEFA 90/15 Transfron3D Project. Special thanks are addressed to Praxair (Praxair, Inc., Barakaldo 48903, Spain) for their technical and supply supports in this work

Thermomechanical analysis of additively manufactured bimetallic tools for hot stamping

A comparison between a conventional AISI H13 hot stamping tool and a bimetallic tool consisting of an AISI 1045 core and a laser-deposited AISI H13 coating is performed. In order to analyze the performance of bimetallic tools, the material compatibility and quality of the coating are analyzed. Besides, the mechanical properties are evaluated and compared with those of the conventional tool, obtaining mechanically equivalent results. Nevertheless, the real conductivity of the laser deposited AISI H13 is found to be 16 % lower than the theoretical value. Hence, a thermal model of the hot stamping process is developed, and the performance of various coating thicknesses is evaluated. Results show that, in the present case study, an AISI 1045 tool with a 1 mm AISI H13 coating ensures the mechanical properties and reduces the cycle time by 44.5 % when compared to a conventional AISI H13 tool.e authors gratefully acknowledge the financial support for this study from the European Union, through the H2020-FoF132016 PARADDISE project (contract number 723440) and from the Spanish Ministry of Economy and Competitiveness for the support on the DPI2016-79889-R INTEGRADDI project

Combination of Laser Material Deposition and Laser Surface Processes for the Holistic Manufacture of Inconel 718 Components

The present work proposes a novel manufacturing technique based on the combination of Laser Metal Deposition, Laser Beam Machining, and laser polishing processes for the complete manufacturing of complex parts. Therefore, the complete process is based on the application of a laser heat source both for the building of the preform shape of the part by additive manufacturing and for the finishing operations. Their combination enables the manufacture of near-net-shape parts and afterwards removes the excess material via laser machining, which has proved to be capable of eliminating the waviness resulting from the additive process. Besides, surface quality is improved via laser polishing so that the roughness of the final part is reduced. Therefore, conventional machining operations are eliminated, which results in a much cleaner process. To validate the capability of this new approach, the dimensional accuracy and surface quality as well as the microstructure of the resulting parts are evaluated. The process has been validated on an Inconel 718 test part, where a previously additively built-up part has been finished by means of laser machining and laser polishing.Special thanks are addressed to the Industry and Competitiveness Spanish Ministry for the support on the DPI2016-79889-R INTEGRADDI project and PARADDISE project H2020-IND-CE-2016-17/H2020-FOF-2016 of the European Union's Horizon 2020 research and innovation program

Thermal Diffusivity Measurement of Laser‐ Deposited AISI H13 Tool Steel and Impact on Cooling Performance of Hot Stamping Tools

Additive manufacturing is a technology that enables the repair and coating of high‐addedvalue parts. In applications such as hot stamping, the thermal behavior of the material is essential to ensure the proper operation of the manufactured part. Therefore, the effective thermal diffusivity of the material needs to be evaluated. In the present work, the thermal diffusivity of laser‐deposited AISI H13 is measured experimentally using flash and lock‐in thermography. Because of the fast cooling rate that characterizes the additive process and the associated grain refinement, the effective thermal diffusivity of the laser‐deposited AISI H13 is approximately 15% lower than the reference value of the cast AISI H13. Despite the directional nature of the process, the laser‐deposited material’s thermal diffusivity behavior is found to be isotropic. The paper also presents a case study that illustrates the impact of considering the effective thermal conductivity of the deposited material on the hot stamping process.The authors gratefully acknowledge the financial support for this study from the European Union, through the H2020-FoF13-2016 PARADDISE project (contract number 723440) and from the Ministry of Economy and Competitiveness (grant number DPI2016-77719-R)

Txirbil-harroketan erabilitako ebaketa-jariakinaren eragina laser bidezko prozesu gehigarrian konformaziorako trokelen konponketaren kasuan

The combination of additive and subtractive manufacturing processes is especially useful for repairing complex geometries and high-added-value components. The best solution for combining both processes is to integrate them in a single machine. Nevertheless, this combination entails a series of challenges, such as the impact that the use of cutting fluids in the subtractive operation may have on the subsequent additive process. In view of this situation, the present work aims to evaluate the effects of the deposition of AISI H13 hot work tool steel on a substrate impregnated with cutting fluid. For this purpose, different oil concentrations have been considered, and the attained results have been compared with the reference tests, performed on a clean substrate. In addition to morphological variations, it has been observed that when high oil concentrations are used, the deposited material is cracked, invalidating the parts manufactured through this approach. Therefore, in the case of AISI H13 tool steel, it has been determined that a cleaning stage is highly necessary in order to remove any cutting fluid that may be on the surface of the substrate before the additive operation is performed.; Fabrikazio-prozesu gehigarri eta kengarrien arteko konbinaketa oso erabilgarria da geometria konplexuko eta balio-erantsi altuko piezen konponketarako. Prozesuak bateratzeko aukera onena haiek makina bakarrean barneratzea da. Alabaina, bateratze horretan erronka anitz agertzen dira, besteak beste, mekanizazio-prozesuan erabiltzen diren ebaketa-jariakinek jarraiko gehitze-prozesuan izan dezaketen eraginaren ezjakintasunaren ondorioz.Egoera horren aurrean, berotako trokelgintzan ohikoa den AISI H13aren kasurako ebaketa-jariakinarekin kutsaturiko gainazalean laser bidez materiala eranstean ager daitezkeen akatsen azterketa gauzatu da. Olio-maila anitzekin egin dira saiakuntzak, eta gainazal garbian egindako erreferentziazko saiakuntzarekin alderatu dira lorturiko emaitzak. Aldaera morfologikoak nabaritzeaz gain, % 100 olio-kontzentrazioko ebaketa-jariakina erabiltzen den kasuan erantsitako materiala arrakalatu egiten dela ikusi da, eta egoera horretan fabrikaturiko piezak baliogabetu egiten dira. Hortaz, beharrezkoa dela ikusi da AISI H13aren kasuan gehitze-prozesuaren aurretik gainazalean egon daitezkeen ebaketa-jariakinen garbiketa