Innovative Process Design and Processing for Advanced Structural Materials: Poster Session
Program Organizers: Ju-Young Kim, UNIST; Jae-il Jang, Hanyang University; Sung-Tae Hong, University of Ulsan; Rongshan Qin, The Open University
Monday 5:00 PM
October 10, 2022
Room: Ballroom BC
Location: David L. Lawrence Convention Center
Session Chair: Ju-Young Kim, UNIST; Sukbin Lee, UNIST
K-2: Automated Process Design for Heat Shrink Casing of Welded Parts of Buried District Heating Pipe: Hyung-Gyu Kim1; Jooyong Kim2; Hae-Yong Lee2; Jonghun Yoon1; 1Hanyang University; 2Korea District Heating Corporation (KDHC)/Frontier Research & Training Institute
The lifespan of the general District Heating (DH) pipe is about 30 years, and a significant amount of the buried district heating pipe is nearing the time of replacement. A district heating pipe used for a long time may cause a defect in a vulnerable area as heat contraction and expansion are repeated, and this could lead to a personal accident as the district heating pipe is ruptured, so it is essential to replace it at an appropriate season. Currently, the district heating pipe has been replaced depending on the worker’s know-how, so the quality of the welding part is not uniform, and the work take a considerable amount of time. In this paper, we propose an automated equipment that uniformly heats the polyethylene outer pipe and then seals the joint in the electric fusion welding method, and proposes an optimal construction method for quality uniformly.
Cancelled
K-3: Developing NiTi for a Stable Two-way Shape Memory Behavior: Mitchell Bauer1; Mohammad Mahtabi1; 1University of Tennessee at Chattanooga
Shape memory alloys (SMAs) exhibit unique shape recovery behaviors. The Two-Way Shape Memory (TWSM) effect is the shape change of an SMA due to pure temperature change in the absence of any mechanical load. TWSM effect material is processed to take two preset shapes at “high” and “low” temperatures. In this study, a reliable method is proposed to shape-set a NiTi alloy for a stable TWSM response. The percent recovery and accuracy of the programmed shape in TWSM effect were studied by investigating different methods of processing. Reliable methods to shape-set the alloy were determined based on the accuracy of retrieved shape and the stability of shape recovery over numerous cycles. Specimens were thermomechanically trained then underwent 10-20 heating-cooling cycles to evaluate the cyclic stability. Various shape-setting temperatures and their resulting microstructures were analyzed to find the most effective method for accurate shape recovery and cyclic stability.
K-4: Development of a Gradient Structural Material Using Electrically Assisted Pressure Joining of Fe-Mn-Al-C Lightweight Steels: Siwhan Lee1; Howook Choi1; Chanwoo Jeong1; Joonoh Moon2; Heung Nam Han1; 1Seoul National University; 2Changwon National University
Lightweight steels of Fe-Mn-Al-C system are drawing great attention due to superior mechanical properties. The combination of strength and elongation of Fe-Mn-Al-C steels can be controlled by nano-sized κ-carbide precipitation, which is significantly affected by Si and Mo addition. In this study, a novel structural material with hardness gradient was fabricated by solid-state bonding of two Fe-Mn-Al-C-based lightweight steels containing Mo and Si, respectively, using electrically assisted pressure joining (EAPJ). It was confirmed that the EAPJed material had excellent bonding strength through tensile test. Through EPMA observation, it was observed that Si and Mo diffusion occurred actively into two base materials during EAPJ. Since the addition of Si promotes the precipitation kinetics of κ-carbide whereas Mo retards it, a significant gradient of precipitate distribution was found. As a result, it was possible to fabricate a new structural material with a hardness gradient of about 100 HV in 0.5 mm.
K-5: Development of a Self-heated Composite Tool for Out of Autoclave and Out of Oven Cure of Thin Ply Composite Structures: Dwayne R. Morgan1; 1Touchstone Research Laboratory
A lightweight self-heating composite tool is described that contains a graphite foam core and independent heater control for enhancing temperature uniformity and resin stability during cure. The technology is an alternative to conventional oven and autoclave curing of large composite structures. Moreover the out of autoclave (OOA) and out of oven (OOO) composite tool technology should significantly reduce high operational costs and increase productivity in large structural composites manufacturing. The research was made possible through the NASA Phase I and Phase II Small Business Technology Transfer (STTR) program. In this effort the heater and power supply requirements were defined. A prototype tool was constructed for characterizing heat transfer, surface temperature uniformity, and to verify analytical results. The planned application will be for OOA-OOO curing of NASA Deployable Composite Boom (DCB) technology manufactured from thin-ply composites and that span 100 meters in length when deployed.
K-6: Development of Highly Stretchable and Impermeable Encapsulation by Applying Wavy-structure to Thermally Grown Silicon Dioxide: Hangeul Kim1; Gyeong-Seok Hwang1; Hyeonji Yoo1; Sohyeon Lee1; Ju-Young Kim1; 1UNIST
Stretchable organic light-emitting diodes require encapsulations with high stretchable and low water-vapor transmittance rate to ensure long-term operation. A thermally-grown silicon dioxide has an extremely water vapor transmittance rate due to a high density without defects, but it has low an elastic limit and shows a brittle fracture. Fortunately, stretchability can be increased by structure design of materials. Here, we develop the highly stretchable and impermeable encapsulations by applying a wavy-structure to the thermally-grown SiO2. By theoretically analyzing mechanical behaviors of wavy-structured SiO2, the correlation between stretchability and characteristics of wavy-structured SiO2 were carried out. Through barrier properties after cyclic deformation with 90% of stretchability during 1000 cycles, it was confirmed that mechanical reliability of the wavy-structured SiO2.This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (2020R1A5A6017701) and the Ministry of Trade, Industry and Energy (MOTIE, Korea) (20011735)
K-7: Discontinuous Yielding Behavior Due to Twinning Accompanied by Abnormal Grain Growth in Fine-grained Copper: Byeong-Seok Jeong1; Woojin Cho1; Siwook Park1; Leeju Park2; Keunho Lee2; Heung Nam Han1; 1Seoul National University; 2Agency for Defense Development
The equiaxed fine-grained copper specimen fabricated by powder injection molding supplemented with hot isostatic pressing showed a yield point phenomenon with Lüders-type deformation. Abnormal grain growth accompanied by twinning occurred only in the region swept by the Lüders band. Consequently, the microstructure of Lüders band region transformed into bimodal grain structure composed of fine grains and abnormally coarse grains containing a large amount of twin. The active variant of the twin formed during abnormal grain growth was identified through EBSD (electron backscatter diffraction). Afterwards, the strain accommodated by the twinning was calculated based on a phenomenological theory. Based on this result, it was confirmed that the strain burst caused by the sudden occurrence of a large amount of twin could cause the yield point phenomenon of the fine-grained copper specimen.
K--8: Effect of Heat Treatment in 9% Ni Steels on Cryogenic Impact Toughness: Younghoon Kim1; Eunji Song1; Sohyeon Lee1; Minho Park2; Hyunbo Shim2; Ju-Young Kim1; 1UNIST (Ulsan National Institute of Science and Technology); 2Hyundai Steel
Recently, the application of alternative energy is expanding due to the reinforcement of eco-friendly policies so, the demand for the development of cryogenic materials that can be used for storage/transportation of eco-friendly fuels is increasing. In cryogenic temperature, material becomes brittle because of ductile to brittle transition (DBTT). Therefore, cryogenic material should have good cryogenic toughness. Retained austenite (RA) play an important role in affecting cryogenic toughness. Since the microstructure and mechanical properties are affected by the heat treatment, it is necessary to understand the effect of the heat process.In this study, we analyze the microstructure and mechanical property of 9 % Ni steels which are produced by QT (Quenching and tempering) process and QLT (L: lamellarizing) process, respectively. We compare volume fraction, morphology and distribution of RA. Also, we compare mechanical property by using indentation size effect of nanoindentation. This work was supported by Hyundai Steel.
K-9: Enhanced Flaw-tolerance of Nanoporous Gold with Grain Boundary Plasticity: Eunji Song1; Younghoon Kim1; Gyeong-Seok Hwang1; Ju-Young Kim1; 1UNIST
Nanoporous gold(np-Au) is material composed of continuously connected ligament and pore. Due to low density and high surface area-to-volume ratio, np-Aus apply to catalyst, actuator, and sensor. However, np-Au has brittle behavior as an issue to be overcome. Brittleness and flaw-sensitivity appear because pore acts as stress concentration site and ligaments are sequentially failed right after crack nucleation. Grain boundary is, also, another cause of stress concentration, so early crack nucleation is observed in grain boundary. For the enhancement of flaw-tolerance, we focus on grain size and grain morphology to activate grain boundary plasticity. We prepare np-Aus with coarse grain, fine grain, and anisotropic grain structure. Fracture toughness is measured with single edge notched tension(SENT), and flaw-tolerance is investigated by micro tensile test and digital image correlation (DIC) method.This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (2020R1A5A6017701 and 2021R1F1A1051001).
K-12: Improvement of Structural Stability and Characterization of Nanoscale Defects in Amorphous Alumina Thin Film: Jeong-Hyun Woo1; Gyeong-Seok Hwang1; Hyeonji Yoo1; Ju-Young Kim1; 1UNIST
Amorphous alumina thin films grown by atomic layer deposition (ALD) have been used for flexible devices as a dielectric layer and encapsulation due to their high density. However, oxide materials such as alumina and silica have brittle behavior and low flexibility. In this study, 50 nm thick-alumina thin films show an elastic limit of 3.09% through tensile tests. However, encapsulation performance degrades even after cyclic deformation within elastic limit by pinhole formation. To improve structural stability and suppress pinhole formation, plasma pre-treatment is introduced before ALD process to form OH- ligands and eliminate the dangling bonds that cause the pinhole formation. In this study, we analyze the mechanism of pinhole formation by XPS analysis and MD simulation. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (2020R1A5A6017701) and the Ministry of Trade, Industry and Energy (MOTIE, Korea) (20011735)
K-13: Integrated Welding and Thermal Processing for Ferritic/Martensitic Steels: Daniel Codd1; Joseph McCrink2; 1KVA Stainless/University of San Diego; 2KVA Stainless
Ferritic/Martensitic steels are favored for their strength, high temperature performance and weight reduction potential in structural applications. Conventional weldments require post weld heat treatments (PWHT) to restore material performance; alternative solid-state or adhesive joining methods can limit design flexibility. The primary objective of this work is to demonstrate a proof-of-concept for an integrated welding and thermal processing joining method to improve the ductility and toughness of as-welded joints without subjecting the assembly to a separate energy intensive PWHT, which is associated with risks of distortion and cracking. The improvements in properties afforded by such a method can greatly expand the design opportunities for high performance structural components.
K-14: MatILDa® - Application of a User-oriented Material Database: Michael Kruse1; Margarita Bambach2; Kristin Helas2; Doris Wehage2; 1Friedrich Kocks GmbH & Co. KG; 2GMT- Gesellschaft für metallurgische Technologie- und Softwareentwicklung mbH
Sustainability, digitalization and the constant demand for enhanced material properties – those are the motors driving the optimization of various processes. An approach of high and by far not exhausted potential is the use of realistic material parameters. The material database MatILDa® offers just that: It is a user-friendly tool that provides comprehensive data on material properties. After a brief introduction to the material science database, three different examples will demonstrate this application’s potential.In the first case, material parameters and intelligent algorithms aid the development of a control system for induction heating devices. The second example illustrates the use of MatILDa® for the realistic mapping of material properties during the FEM-simulation. The third and final example sees the material science database used in process simulation for long products. As a digital twin of rolling mills, the simulation software focuses on the specific microstructure evolution.
K-15: Porous Silicon Carbide (SiC) for Composite Core Sandwich Structures: Dwayne R. Morgan1; 1Touchstone Research Laboratory
Composite core materials enhance performance of composite structures by reducing weight, adding stiffness, and providing impact resistance and energy absorption. Major limitations of common composite core materials like balsa and polymer foams are that they cannot withstand high heat load for use in aerospace hot structure environments. Carbon foams have higher heat resistance but nonetheless are susceptible to significant weight loss when subjected to oxidizing atmosphere above 500 C.Porous silicon carbide has been developed that has up to 60% porosity and load bearing. The prod-uct is manufactured using net-shape molding techniques and is under consideration as a lightweight high temperature composite core. Silicon carbide is stable at high temperature and routinely used up to 1600 C. The porous silicon carbide is anticipated to provide added stiffness and improved creep resistance for aerospace hot structures. Examples of molded shapes will be presented along with material properties and characteristics.
K-16: Solid-state Bulk Joining of Dissimilar Metal Alloys by Electrically Assisted Pressure Joining: Shengwei Zhang1; Thanh Thuong Do1; Bui Thi Tu Anh1; Sung-Tae Hong1; Howook Choi2; Heung Nam Han2; 1University of Ulsan; 2Seoul National University
Bulk solid-state joints of various combinations of dissimilar metal alloys are successfully fabricated by electrically assisted pressure joining (EAPJ) technique. The quality of joints was evaluated by microstructural analysis and mechanical testing. The microstructural analysis results confirm that solid-state joints without macro and micro-defects are fabricated through elemental diffusion and recrystallization during EAPJ. The results of quasi-static tensile tests show that base metal fracture rather than interface fracture can be achieved by adjusting input parameters. Moreover, for the material combination of SUS316L and SUS410, the fatigue behavior of the joints is evaluated by a P-S-N curve using two-parameter Weibull distribution. Finally, the results of experiments with combinations of non-ferrous metal alloys confirm that the concept of EAPJ is also applicable to non-ferrous metal alloys, including copper or aluminum alloys. The present study demonstrates that EAPJ is an efficient method in the bulk joining of dissimilar metal alloys combinations.
K-17: Study on the Behavior of Fine Particles by the Vibration of the Medium with Polluted Air Inside the Rigid Housing: Hyo-Soo Lee1; Hai-Joong Lee1; Tae-Hoon Park1; Ki-Buem Kim2; Taek-Jib Choi2; Jin-Kyu Lee3; 1KITECH; 2Sejong University; 3Kongju National University
The fine particles in the media such as air and water have been recently caused environmental pollution. Especially, the fine dust in the polluted air has been challenged to solve with conventional techniques such as physical filtering, electrostatic precipitator, green wall, etc. We investigated the innovative technology for agglomerating the dispersed fine particles in air induced by acoustic waves with the frequency ranging from 20Hz to 20kHz, which is designed to possibly reflect in-phase waves within the various rigid housings. When the low frequency under 50Hz was applied in the rigid housings with ultra-fine particles, the rate of agglomeration of ultra-fine particles was nearly 5 times higher than that without operating. It is concluded that the agglomeration behavior of ultra-fine particles was effectively induced by an acoustic wave, and also is expected to be applied to the inter-structure and intra-structure having the polluted air.
K-18: The Friction and Product Quality in Dry Metal Forming with Volatile Media: Lihong Cai1; Sung-Tae Hong1; Jincheol Kim1; 1University of Ulsan
An approach of using volatile media (CO2) as a lubricant for the dry metal forming process has been integrated with additively manufactured (AMed) dies. The performance of volatile media to reduce friction and improve product quality is confirmed in the pull-out tests. Note that the evaporation of CO2 leaves no residue, which is conducive to environmental protection. In the pull-out test, the liquid CO2 is supplied through AMed dies with microholes in the dies and sprayed into the contact zone between the dies and sheet to function as a lubricant. The result shows that CO2 pressure and microhole geometry have a significant effect on friction performance.