scholarly journals Additive manufacturing of steels: a review of achievements and challenges

2020 ◽  
Vol 56 (1) ◽  
pp. 64-107 ◽  
Author(s):  
Nima Haghdadi ◽  
Majid Laleh ◽  
Maxwell Moyle ◽  
Sophie Primig
Keyword(s):  
Additive Manufacturing ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Layer By Layer ◽  
Powder Bed ◽  
Heating Source ◽  
Wide Range ◽  
Complex Engineering ◽  
Precipitation Phenomena ◽  
Directed Energy

Abstract Metal additive manufacturing (AM), also known as 3D printing, is a disruptive manufacturing technology in which complex engineering parts are produced in a layer-by-layer manner, using a high-energy heating source and powder, wire or sheet as feeding material. The current paper aims to review the achievements in AM of steels in its ability to obtain superior properties that cannot be achieved through conventional manufacturing routes, thanks to the unique microstructural evolution in AM. The challenges that AM encounters are also reviewed, and suggestions for overcoming these challenges are provided if applicable. We focus on laser powder bed fusion and directed energy deposition as these two methods are currently the most common AM methods to process steels. The main foci are on austenitic stainless steels and maraging/precipitation-hardened (PH) steels, the two so far most widely used classes of steels in AM, before summarising the state-of-the-art of AM of other classes of steels. Our comprehensive review highlights that a wide range of steels can be processed by AM. The unique microstructural features including hierarchical (sub)grains and fine precipitates induced by AM result in enhancements of strength, wear resistance and corrosion resistance of AM steels when compared to their conventional counterparts. Achieving an acceptable ductility and fatigue performance remains a challenge in AM steels. AM also acts as an intrinsic heat treatment, triggering ‘in situ’ phase transformations including tempering and other precipitation phenomena in different grades of steels such as PH steels and tool steels. A thorough discussion of the performance of AM steels as a function of these unique microstructural features is presented in this review.

Compact back-scattered electrons' energy analyzer for standard SEM

1994 ◽  
Vol 52 ◽  
pp. 488-489
Author(s):  
S. Likharev ◽  
A. Kramarenko ◽  
V. Vybornov
Keyword(s):  
Depth Resolution ◽  
High Energy ◽  
Primary Beam ◽  
Layer By Layer ◽  
Energy Analyzer ◽  
High Energy Part ◽  
Small Window ◽  
Energy Part ◽  
Wide Range ◽  
High Voltage Supply

At present time the interest is growing considerably for theoretical and experimental analysis of back-scattered electrons (BSE) energy spectra. It was discovered that a special angle and energy nitration of BSE flow could be used for increasing a spatial resolution of BSE mode, sample topography investigations and for layer-by layer visualizing of a depth structure. In the last case it was shown theoretically that in order to obtain suitable depth resolution it is necessary to select a part of BSE flow with the directions of velocities close to inverse to the primary beam and energies within a small window in the high-energy part of the whole spectrum.A wide range of such devices has been developed earlier, but all of them have considerable demerit: they can hardly be used with a standard SEM due to the necessity of sufficient SEM modifications like installation of large accessories in or out SEM chamber, mounting of specialized detector systems, input wires for high voltage supply, screening a primary beam from additional electromagnetic field, etc. In this report we present a new scheme of a compact BSE energy analyzer that is free of imperfections mentioned above.

scholarly journals A STRUCTURED APPROACH TO REDUCE DESIGN ITERATIONS IN ADDITIVE MANUFACTURING

2021 ◽  
Vol 1 ◽  
pp. 231-240
Author(s):  
Laura Wirths ◽  
Matthias Bleckmann ◽  
Kristin Paetzold
Keyword(s):  
Additive Manufacturing ◽  
Spare Parts ◽  
Design Guidelines ◽  
Final Part ◽  
Layer By Layer ◽  
Powder Bed ◽  
Batch Sizes ◽  
Manufacturing Technologies ◽  
Structured Approach ◽  
Design Freedom

AbstractAdditive Manufacturing technologies are based on a layer-by-layer build-up. This offers the possibility to design complex geometries or to integrate functionalities in the part. Nevertheless, limitations given by the manufacturing process apply to the geometric design freedom. These limitations are often unknown due to a lack of knowledge of the cause-effect relationships of the process. Currently, this leads to many iterations until the final part fulfils its functionality. Particularly for small batch sizes, producing the part at the first attempt is very important. In this study, a structured approach to reduce the design iterations is presented. Therefore, the cause-effect relationships are systematically established and analysed in detail. Based on this knowledge, design guidelines can be derived. These guidelines consider process limitations and help to reduce the iterations for the final part production. In order to illustrate the approach, the spare parts production via laser powder bed fusion is used as an example.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

Additive Manufacturing of Nickel-Based Super Alloys for Aero Engine Applications

2020 ◽  
pp. 48-70
Author(s):  
Raja A. ◽  
Mythreyi O. V. ◽  
Jayaganthan R.
Keyword(s):  
Additive Manufacturing ◽  
Complex Geometry ◽  
Source Parameters ◽  
Raw Material ◽  
Layer By Layer ◽  
Powder Bed ◽  
Complex Design ◽  
Direct Energy ◽  
Second Phases ◽  
Metal Addition

Ni based super alloys are widely used in engine turbines because of their proven performance at high temperatures. Manufacturing these parts by additive manufacturing (AM) methods provides researchers a lot of creative space for complex design to improve efficiency. Powder bed fusion (PBF) and direct energy deposition (DED) are the two most widely-used metal AM methods. Both methods are influenced by the source, parameters, design, and raw material. Selective laser melting is one of the laser-based PBF techniques to create small layer thickness and complex geometry with greater accuracy and properties. The layer-by-layer metal addition generates epitaxial growth and solidification in the built direction. There are different second phases in the Ni-based superalloys. This chapter details the micro-segregation of these particles and its influence on the microstructure, and mechanical properties are dependent on the process influencing parameters, the thermal kinetics during the process, and the post-processing treatments.

scholarly journals An Overview of Additive Manufacturing Technologies—A Review to Technical Synthesis in Numerical Study of Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3895 ◽  
Author(s):  
Abbas Razavykia ◽  
Eugenio Brusa ◽  
Cristiana Delprete ◽  
Reza Yavari
Keyword(s):  
Numerical Simulation ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Part Quality ◽  
Melt Pool ◽  
Wide Range ◽  
Am Processes

Additive Manufacturing (AM) processes enable their deployment in broad applications from aerospace to art, design, and architecture. Part quality and performance are the main concerns during AM processes execution that the achievement of adequate characteristics can be guaranteed, considering a wide range of influencing factors, such as process parameters, material, environment, measurement, and operators training. Investigating the effects of not only the influential AM processes variables but also their interactions and coupled impacts are essential to process optimization which requires huge efforts to be made. Therefore, numerical simulation can be an effective tool that facilities the evaluation of the AM processes principles. Selective Laser Melting (SLM) is a widespread Powder Bed Fusion (PBF) AM process that due to its superior advantages, such as capability to print complex and highly customized components, which leads to an increasing attention paid by industries and academia. Temperature distribution and melt pool dynamics have paramount importance to be well simulated and correlated by part quality in terms of surface finish, induced residual stress and microstructure evolution during SLM. Summarizing numerical simulations of SLM in this survey is pointed out as one important research perspective as well as exploring the contribution of adopted approaches and practices. This review survey has been organized to give an overview of AM processes such as extrusion, photopolymerization, material jetting, laminated object manufacturing, and powder bed fusion. And in particular is targeted to discuss the conducted numerical simulation of SLM to illustrate a uniform picture of existing nonproprietary approaches to predict the heat transfer, melt pool behavior, microstructure and residual stresses analysis.

scholarly journals Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 341 ◽  
Author(s):  
Eleonora Santecchia ◽  
Stefano Spigarelli ◽  
Marcello Cabibbo
Keyword(s):  
Additive Manufacturing ◽  
Side Effects ◽  
Metal Powder ◽  
Three Dimensional ◽  
High Energy ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Metal Additive Manufacturing ◽  
Metal Additive

Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser–powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects.

scholarly journals Sensor-Based Additive Manufacturing Technologies

2021 ◽  
Vol 12 (3) ◽  
pp. 3513-3521
Keyword(s):  
Additive Manufacturing ◽  
Wearable Sensors ◽  
Sensor Technology ◽  
Layer By Layer ◽  
Environmental Sensors ◽  
Direct Energy Deposition ◽  
Powder Bed ◽  
Direct Energy ◽  
Building Components ◽  
Manufacturing Technologies

Additive manufacturing is the term that uses the CAD data to build components layer by layer; it is also termed layered manufacturing or 3D printing. The major advantage of additive manufacturing is the capability of building components without the use of molds or tools. Five major categories of AM processes include Powder Bed Fusion (PBF), Direct Energy Deposition (DED), Material Jetting (MJ), Binder Jetting (BJ), and Sheet Lamination (SL). The sensor may be defined as a device that responds to a physical stimulus and transmits a resulting impulse. Sensor technology has been widely adopted in advanced manufacturing, aerospace, biomedical and robotic applications. Commonly used sensors are temperature sensors, strain sensors, biosensors, environmental sensors, and wearable sensors, etc. Additive manufacturing technologies can fabricate sensors and microfluidic devices with less labor. This paper focuses on various sensors developed by additive manufacturing processes, and their practical application for the particular purpose is reviewed.

Effect of Build Direction in Direct Metal Laser Sintering (DMLS) of Inconel 718 on Microstructure and Mechanical Behavior

2019 ◽  
Author(s):  
Sachin Alya ◽  
Chaitanya Vundru ◽  
Ramesh Singh ◽  
Khushahal Thool ◽  
Indradev Samajdar ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Behavior ◽  
Inconel 718 ◽  
Laser Sintering ◽  
Thermal Gradients ◽  
Layer By Layer ◽  
Direct Metal Laser Sintering ◽  
Powder Bed ◽  
Grain Orientations ◽  
End Use

Abstract Additive manufacturing (AM) technology is gaining enormous popularity in the manufacturing industries. The continuous improvements made in the AM processes features development of 3D metallic prototypes as well as fully functional end-use components. Direct Metal Laser Sintering (DMLS) is a pre-placed powder bed based technique, in which a thin layer of powder is place over the build tray and the areas need to be sintered are exposed to the laser. In the current work the microstructural and mechanical behavior of Inconel 718 parts produced by DMLS are investigated. As the DMLS produces parts in a layer by layer fashion, the orientation of parts with respect to the build direction is an important criterion. Microstructure and mechanical properties of the produce differs depending upon the orientation. This paper emphasize on the variation of grain sizes and grain orientations developed in the components built with different orientations. Another common issue with the additive manufacturing is the development of the residual stresses in the components arising due to the differential thermal gradients experienced during processing. The variation of the residual stress generated in the produced parts has also been characterized and modeled.

Effect Ultrasonic Nanocrystal Surface Modification (UNSM) Treatment on Fatigue Strength of Additive Manufactured UNS S31603

2020 ◽  
Author(s):  
Young Sik Pyun ◽  
Ruslan Karimbaev ◽  
Seimi Choi ◽  
Jun Suek Ro ◽  
Choong Ho Sanseong ◽  
...  
Keyword(s):  
Surface Modification ◽  
Additive Manufacturing ◽  
Fatigue Strength ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Complex Geometry ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Wide Range

Abstract Additive Manufacturing (AM) which is also known as metal 3D printing technique is one of the promising manufacturing processes due to the capability to process a complex geometry component. This is implemented in wide range of applications in various industries such as automotive, aerospace, power plants, etc. The aging nuclear power plant components and the obsolescence of those components has become a concern in this industry, and AM has come as an alternative solution for this matter. The Board on Pressure and Technology Codes and Standards (BPTCS) and Board on Nuclear Codes and Standards (BNCS) Special Committees started to study the application of Powder Bed Fusion (PBF) technique for pressure retaining equipment made from UNS S31603. Also, later Korean International Working Group (KIWG) was also started a Task Group on Additive Manufacturing for Valves which focusing on Powder Bed Fusion (PBF) and Direct Energy Disposition (DED) process for pressure-retaining valve manufacturing especially for nuclear power plant application with the same material. However, the poor mechanical properties and performance, especially fatigue strength of AM materials become a concern due to the defects and flaws as the results of layering and multiple interfaces and welding related discontinuities. In this study, the fatigue strength of PBF and DED manufactured and Ultrasonic Nanocrystal Surface Modification (UNSM) treated UNS S31603 austenitic stainless steel was investigated.

Sign in / Sign up

Export Citation Format

Share Document