Additive Manufacturing of Metals: Microstructure, Properties and Alloy Development: Fe-based Alloys II
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Jurgen Eckert, Erich Schmid Institute of Materials Science; Zhi Wang, South China University of Technology
Tuesday 8:00 AM
October 11, 2022
Room: 301
Location: David L. Lawrence Convention Center
Session Chair: Marissa Brennan, General Electric; Evan Handler, Naval Surface Warfare Center Carderock Division
8:00 AM
Aging Response of Laser Powder Bed Fusion 17-4PH Stainless Steel: Evan Handler1; Katherine Fowler1; Aidan Cowhig1; Caroline Vail1; 1Naval Surface Warfare Center
Laser Powder Bed Fusion (LPBF) has garnered interest for its ability to create geometrically accurate, complex, and critical parts out of various metal powders. However, the process physics induce fast cooling rates and extensive reheating in the material, leading to microstructures that are noticeably different than those present in material manufactured using traditional methods. This issue is doubly significant as these unusual microstructures impede traditional transformation mechanisms that occur in traditionally manufactured material when undergoing standard heat treatment procedures. Naval Surface Warfare Center, Carderock Division studied the heat treatment response of the aging step 17-4PH stainless steel produced using LPBF across multiple systems, while holding the stress relief and solution treatment constant. Resultant material underwent tensile testing and microstructure was investigated optically. This presentation outlines the variations in characterization and performance when using a variety of heat treatment schemes in order to find an ideal method optimized for tensile performance.
8:20 AM
The Effect of Build Height on the Metallurgical Characteristics of 17-4 PH Stainless Steel Manufactured through DED: Ipfi Mathoho1; Powel Tshikalange1; Nana Arthur1; 1CSIR Pretoria
Research in additive manufacturing (AM) technologies have brought into light many aspects of the industry. Many factors such as process parameters have been identified to influence the performance of built parts. This project investigates the effects of part geometry on the mechanical properties of 17-4 PH stainless steel produced through DED. specimens. Four coupons with varying heights: 5 mm, 10 mm, 15 mm, and 20 mm were printed using the same process parameters. The metallurgical characteristics investigated includes, porosity, microstructural evolution, microhardness and corrosion behaviour. It was found the build height does not have any meaningful effect on porosity, while on the otherhand it plays a role in the morphology of delta ferrite. With regards to microhardness and corrosion behavior, it was found that the former decreased due to increments of build height. While the corrosion resistance was found to deteriorate due to build height reduction.
8:40 AM
Laser Powder Bed Fusion of 14YWT Oxide Dispersion Strengthened Steel Produced Using Gas Atomized Reaction Synthesis Precursor Powder: Sourabh Saptarshi1; Timothy Horn1; Chrisopher Rock1; Djamel Kaoumi1; Matthew DeJong1; Iver Anderson2; Jennifer Forrester1; Timothy Prost2; Ralph Napolitano3; Emma White4; 1North Caroline State University; 2AMES Laboratory; 3Iowa State University; 4DECHEMA Forschungsinstitut
Thermally and mechanically stable nano oxide dispersoid spread throughout the grain boundaries in a Fe-Cr Oxide Dispersion Strengthened (ODS) ferritic steel offers excellent creep, fatigue, and improved radiation resistance at high temperatures. Recent progress in Gas Atomization Reaction Synthesis (GARS) technique has shown that rapid solidification of a Cr-rich matrix resulted in the formation of stable Y-containing intermetallic Y2Fe17 on the interior of the powder, and a stable Cr-rich oxide surface. This research focuses on exploring the feasibility of 14YWT composition produced by GARS method in the domain of laser powder bed fusion additive manufacturing method under different atmospheric conditions (Argon and Argon + different oxygen % by weight) and extensively evaluate and analyze the microstructure properties of samples printed under different process parameter and atmospheric conditions. This research also aims to create a process map that will identify parameters that yield ≥ 95% relative density and process stability/repeatability.
9:00 AM
Laser Powder Bed Fusion of Ultra-High Strength Steel from Gas Atomized Powders: Thinh Huynh1; Kevin Graydon1; Nemanja Klejstan2; Marko Knezevic2; Brandon McWilliams3; Kyu Cho3; Yongho Sohn1; 1University of Central Florida; 2University of New Hampshire; 3DEVCOM US Army Research Laboratory
A novel ultra-high strength steel alloy was gas atomized to produce powder feedstock for the fabrication of components via laser powder bed fusion (LPBF). Charge alloys were inductively melted with Argon shrouding at a superheating temperature of 1800 °C and subsequently gas atomized using Argon gas at a pressure of 2 MPa. LPBF optimization was performed as a function of laser power and scan speed, and relative density above 99 % was obtained using 200 W and 800 mm/s. The as-fabricated LPBF specimens consisted of supersaturated austenite primed for quench and temper martensitic transformation. Changes in the as-built microstructure and phase constituents were documented as a function of laser scan speed using electron microscopy and x-ray diffraction. Tensile properties and hardness were examined to assess the alloy’s mechanical behavior as functions of various heat treatments along with correlated microstructural development.
9:20 AM
Mechanical and Microstructure Analysis of 4130 Steel Alloy Produced Using Laser Powder Bed Fusion: Joy Forsmark1; Eric Poczatek1; Yun Bai1; Emily Wolbeck1; 1Ford Motor Company
Recently, there has been interest within the automotive industry in a heat treatable, high strength, low alloy steel powder for use in additive manufacturing technologies. 4130 is a chromium and molybdenum containing alloy that can be produced in powder form. In this study, rods of 4130 alloy were produced using laser powder bed fusion under optimized process parameters. The samples were then heat treated according to different profiles. Metallographic analysis was performed to determine the different phases present at different heat treatments. Hardness and tensile data was also collected and compared. The goal was to gain a comprehensive understanding of the properties of this material under different conditions to provide design guidance for future applications.
9:40 AM
Effect of Post-heat Treatment on the Microstructure and Mechanical Properties of High-carbon High-chromium Tool Steel Manufactured by Direct Energy Deposition: Jung-Hyun Park1; Kyu-Sik Kim2; Jin-Young Kim3; Yong-Mo Koo4; Jong-Bae Jeon5; Kee-Ahn Lee1; 1Inha University; 2Agency for Defense Development; 3Fusiontech. Corp.; 4Changsung Corp; 5Dong-A University
AISI D2 tool steel was manufactured by using direct energy deposition (DED) process with preheating system. Post-heat treatment was applied to the as-built material. The mechanical properties of DED D2 steel were investigated with heat treatment. Samples were fabricated in bulk type with nearly defect free with over 98% density, and columnar dendrite structure was confirmed. Austenite matrix and eutectic structure were observed in the as-built specimen, and martensite matrix and secondary Cr-rich carbide were detected after heat treatment. Ultimate tensile strength was measured to be 1016MPa, and elongation was 2.4% in the case of as-built material. After heat treatment, the maximum tensile strength increased up to 1794MPa and the elongation decreased slightly to 0.8%. On the other hand, compressive yield strength of the as-built material was confirmed to be 1010MPa, and 2260MPa after heat treatment. The deformation and fracture mechanisms of DED D2 tool steels were also discussed.
10:00 AM Break
10:20 AM
Microstructure and Mechanical Property Stability of Wire Arc Additive Manufactured Stainless Steels after Long-Term Thermal Aging: Juan Gonzalez1; Luc Hagen1; Stephen Tate1; Jonah Klemm-Toole1; 1Colorado School of Mines
Austenitic stainless steels are commonly used in power generation and other high-temperature structural applications that are subjected to elevated temperatures over long service lives. The replacement of these components often involves lengthy lead times resulting in power plant outages that are expensive and deteriorate the robustness of the energy infrastructure. Wire arc additive manufacturing (WAAM) has the potential to enable rapid manufacturing of new and replacement parts, but the long-term stability of microstructures and mechanical properties produced by WAAM are not well understood. In this presentation, we will discuss the influences of WAAM deposition parameters and post-build heat treatments on the precipitation of embrittling phases, such as sigma, in commercially available austenitic stainless steel wire feedstocks of 316L, 316LSi, 316H, and 16-8-2 after aging for up to 1000 hours at 650 °C. The implications of embrittling phases on tensile ductility after aging will be discussed.
10:40 AM
The Development of a Directed Energy Depositon (DED) Printability Framework for Improving Part Density and Performance in High Strength Martensitic Steels: Matthew Vaughan1; Michael Elverud1; Jiahui Ye1; Raiyan Seede1; Sean Gibbons2; Philip Flater2; Alaa Elwany1; Raymundo Arroyave1; Ibraham Karaman1; 1Texas A&M University; 2Air Force Research Laboratory
While the directed energy deposition (DED) technology provides a novel and effective way for producing significant grain refinement (by imposing a rapid cooling rate upon solidification), its inherent complexity merits a need for the development of a DED framework that quickly identifies ideal printability spaces for a given steel, thereby enabling printing of materials to full density. Consequently, achieving optimal strengthening in novel high strength martensitic steels via DED and the Hall-Petch effect can be expedited. To address this need, this study proposes a DED printability framework, where an advanced high strength martensitic steel known as AF9628 is printed to full density, high strength, respectable ductility (ρ > 99%, UTS > 1.2 GPa, εf > 10%). The introduced process optimization framework is easily adaptable to other high-end alloys and should prove useful to the research community in accelerating the adaptability of DED in printing to excellent density and mechanical performance.
11:00 AM
L-DED Processability of AISI 410L Stainless Steel: Jeferson Pacheco1; Ana Sofia De Oliveira1; Marcelo Veiga1; Vitor Meura1; Paulo Bloemer1; 1Federal University of Parana
The relationship processability-mechanical properties of metallic alloys through Additive Manufacturing (AM) technology is a constant challenge faced by several industrial segments. Among the different AM processes, Laser-Directed Energy Deposition (L-DED) offers the capability to build large parts from layer-by-layer deposition. However, the thermal cycles inherent to the multilayer deposition directly affect the microstructure and, consequently, the mechanical properties of the AM part. This study is part of an on-going project that asses the relationship microstructure-properties of AM materials aiming to gain a better understanding of procedures to enhance properties of L-DED components using an atomized AISI 410L stainless steel. The microstructure and mechanical properties (measured by microhardness, tensile and impact tests) were characterized in the as-built and heat-treated conditions to address the impact of the multiple thermal cycling. A significantly difference in the mechanical properties was observed in the two proposed conditions, being linked to the microstructure and thermal cycles.