Characterization of Materials and Properties through Metallography, Mechanical Testing and Analysis - From Fundamentals to the Cutting Edge: Quantification, Classification and Simulation of Microstructures and Properties II
Program Organizers: Michael Keeble, Buehler
Wednesday 8:00 AM
October 2, 2019
Location: Oregon Convention Center
Session Chair: Andrew Kitahara, Carnegie Mellon University ; Janet Gbur, Case Western Reserve University; Steven Gentz, NASA Engineering and Safety Center
8:00 AM Invited
Analysis and Comparison of Microstructure and Mineral Properties of Two Kind of Sinters: Ti-bearing and General Sinter: Yapeng Zhang1; Wen Pan1; Zhe Wang2; Shaoguo Chen1; Zhixing Zhao1; 1Shougang Group Co., LTD Research Institute of Technology; 2Shougang Jingtang United Iron &Steel Co.,Ltd
X-ray diffraction, scanning electron microscope, and vickers hardness instrument were applied to analysis the mineral composition, microstructure and mineral structure strength of Ti-bearing sinter and general sinter, both of which were with high basicity. Reasons of differences between Ti-bearing sinter and general sinter in metallurgical properties, such as low temperature reduction degradation and reduction properties, were also analyzed at the same time. the mineral composition of Ti-bearing sinter was more complicated. The inhomogeneity of microstructure and mineral structure strength were more obvious than general sinter, and with the increase of TiO2 content in the sinter it had a tendency to increase the inhomogeneity.
Characterizing Metal Oxide Composites Processed by Internal Oxidation and Severe Plastic Deformation: Anna Weiss1; Jörg Wiezorek2; Yoosuf Picard1; Bryan Webler1; 1Carnegie Mellon University; 2University of Pittsburgh
This work investigates the synthesis and characterization of Fe-Y based metal oxide composites from a bulk alloy instead of by traditional powder metallurgy. The proposed processing method includes the introduction of oxide particles by internal oxidation of a bulk Fe-Y alloy, during which the alloy’s Fe17Y2 intermetallic selectively oxidizes to form yttria particles and pure iron, while the α-Fe matrix remains unchanged. Internal oxidation is followed with severe plastic deformation by equal channel angular pressing (ECAP) to refine the grain size and disperse oxides. Electron microscopy techniques are employed to characterize the effect of oxidation conditions on internal oxidation depth and resulting oxide morphology, coupled with quantitative particle analysis in ImageJ. Further characterization is performed to describe the heavily deformed microstructure after ECAP, and to understand the relationship between oxide particles and the deformation process.
Surface Analysis of Film Formed by Egg Shell Extract on Stainless Steel in Acid Solution: Omotayo Sanni1; API Popoola1; OSI Fayomi1; 1Tshwane University of Technology
The corrosion inhibition of stainless steel in sulphuric acid solution in the presence of egg shell extract (ES) is discussed according to gravimetric method. The morphology of the surface was analyzed using optical microscope and scanning electron microscopy (SEM). The composition of the layer formed on stainless steel surface was estimated using X-ray energy dispersive spectroscopy (EDX) technique. In the absence and presence of ES, SEM images showed that the stainless steel surface was covered with non-uniform layer and uniform adsorbed film, respectively. EDX analysis showed that the surface layer consists of egg shell powder and small quantities of other elements. This study is useful for gaining insights into the view of using egg shell powder regarded as waste for corrosion inhibition of stainless steel in acidic environment.Keywords: stainless steel; surface analysis; gravimetric measurements; SEM; EDX.
9:00 AM Cancelled
Investigation of Thermal Diffusivity for the First Generation Graphitic White Iron: Jie Wan1; Jingjing Qing2; Mingzhi Xu2; 1Missouri University of Science and Technology; 2Georgia Southern University
A new alloy system called graphitic white iron was developed by the authors to improve thermal diffusivity and mitigate over-heating of the wearing surface in the metal-to-metal wear systems. Thermal diffusivity for the first generation graphitic white iron was measured utilizing a laser flash apparatus in accordance with ASTM E1461. Results showed that the thermal diffusivity increased with increasing graphite volume percent in the alloys developed. Hashin-Shtrikman model was applied to investigate the thermal diffusivity of the graphitic white iron, where the alloy was treated as an isotropic composite material and the graphite was considered as the second phase. A comprehensive model was established to correlate thermal diffusivity with the alloy composition.
9:20 AM Cancelled
Investigation of Wear Performance for the First Generation Graphitic White Iron: Jie Wan1; Jingjing Qing2; Mingzhi Xu2; 1Missouri University of Science and Technology; 2Georgia Southern University
One issue for metal-to-metal wear system is the generation of frictional heat can over-heat the wearing surfaces and result in adhesive wear failure. First generation “graphitic white iron,” was developed by the authors, and graphite was introduced into white iron to accelerate the heat dissipation and extend the service life of the metal-to-metal wear components. Wear property for the first generation graphitic white iron was evaluated utilizing a dry sand/rubber wheel apparatus following ASTM G65. Wear scars were analyzed with various characterization techniques. It was found that 1 vol.% graphite had equivalent contribution to 2.33 HRC hardness, with respect to wear resistance. Hard M7C3 carbide was found to effectively interfere with the wearing by serving as wear “stopper”, meanwhile the lower hardness cementite carbide worked as wear “buffer” and prevented the removal of the “stopper”. A numerical model was developed to correlate hardness, graphite volume percent and the wear performance.
Observation of Nanotwin and Ni2Si Discontinuous Precipitation in Cold-drawn Cu-Ni-Si Alloy: Hwangsun Kim1; Jee Hyuk Ahn1; Seung Zeon Han2; Janghyun Jo1; Miyoung Kim1; Heung Nam Han1; 1Seoul National University; 2Korea Institute of Materials Science
Copper alloys have been used for electric devices due to its good electrical conductivity. These materials require not only high electrical conductivity but also high mechanical strength for reliable device application. However, in general, enhancing electrical conductivity and mechanical strength simultaneously were often considered to be mutually exclusive in structural materials. Recently, the improvement of both mechanical strength and electrical conductivity by utilizing Ni2Si discontinuous precipitation (DP) and cold drawing on Cu-Ni-Si alloy has been reported. In this study, we performed microstructural observation using scanning electron microscopy and transmission electron microscopy. We found internal strain development due to the DP. Besides, we observed nanotwin formation during cold drawing Cu-Ni-Si alloy. It is known that the nanotwins have low resistivity and are effective dislocation movement impediments. Therefore, the existence of nanotwins in Cu-Ni-Si alloys implies that their strength can be greatly increased while maintaining the conductivity.
10:00 AM Break
Classification of Steel Microstructures – Tracing Bainite with the Help of Textural Parameters: Martin Mueller1; Frank Mücklich2; Dominik Britz2; Thorsten Staudt3; 1Saarland University; 2Universität des Saarlandes; 3AG der Dillinger Hüttenwerke
Bainite is an essential constituent of modern high strength steels. In addition to the still great challenge of characterization, the classification of bainite poses difficulties. Challenges when dealing with bainite are the variety and amount of involved phases, the fineness and complexity of the structures and that there is often no consensus among human experts in labeling and classifying those. Therefore an objective and reproducible characterization and classification is essential. To achieve this it is necessary to analyze the substructure of bainite using SEM. This work will present how textural parameters calculated from SEM images, taken from benchmark samples with defined structures, can be used to distinguish different bainitic microstructures. It will also show how an already established machine learning approach by means of support vector machine for basic steel microstructures can be applied to bainite subclasses.
Pearlite Spheroidization and Its Relationship with Tensile Strength: Monserrat Lopez1; Hector Vergara-Hernández1; Pedro Garnica-González1; Octavio Vázquez-Gómez1; Sixtos Arreola-Villa2; 1Instituto Tecnologico de Morelia; 2Universidad Autónoma de Coahuila
In this work, continuous cooling treatments were carried out in steels from 0.6 to 0.83% carbon, with the aim of characterizing the spheroidal pearlite obtained in slow cooling treatments and its relationship with the ultimate tensile strength (UTS). With the use of Scanning Electron Microscopy, the pearlite interlamellar spacing for each cooling condition was determined, as well as the diameter of the pearlite colony. Also, with the Abrams method of three circles and the ASTM E-122 Standard, the prior austenitic grain size was determined for the mixture of present phases. With the microstructural parameters and the results obtained through tensile tests, it was determined that the ultimate tensile strength increases with the cooling rate in spheroidization process.
Effect of Process Parameters on the Porosity of Al-7%Si Alloy Castings Produced by Ceramic Shell Investment Casting Process: Balwinder Singh1; Pargeet Chauhan2; 1GZS Campus CET Bathinda; 2Freudenberg NOK Pvt Ltd Mohali
The ceramic shell investment casting (CSIC) process can be utilized to create complex castings at a high production rate and low cost. This paper investigates the effect of process parameters such as mould preheat temperature, pouring temperature, grain finess number (stucco size), firing temperature and firing time on the porosity of Al-7% Si alloy castings in CSIC process. In order to evaluate the effect of selected process parameters, the Response Surface Methodology (RSM) has been used to correlate the independent process variables with the desired porosity by a mathematical model. The analysis of results indicates that the porosity increases with increases mould preheat temperature grain finess number, and pouring temperature whereas, porosity decreases with increases in firing temperature and time imposed.
Development of an Orthogonal Metal Cutting Experiment to Investigate Microstructural Evolution in Friction Stir Welding: Benjamin Lund1; 1University of Alabama in Huntsville
The friction stir welding process results in a weld zone microstructure consisting of fine grains in random orientations. The process parameters controlling this grain refinement are not well understood and test methods to reproduce the hot working conditions of FSW in laboratory experiments are lacking. Estimates of the hot working conditions during FSW are a shear strain greater than 50 and a shear strain rate greater than 10^3 s^-1. The shear surface that forms around the tool during FSW is theorized to be similar to the shear plane formed during orthogonal metal cutting. Based on analytical relationships developed for metal cutting, an orthogonal metal cutting experiment is proposed to simulate the FSW hot working conditions. This would allow validation of the hot working conditions of strain, strain rate, and temperature that result in the microstructure observed. Establishing this link is critical to anchor the development of predictive numerical models.
Phase Fraction Development of Ni2Cr from Isothermal Ageing Conditions: Nicholas Aerne1; Julie Tucker1; 1Oregon State University
In this report synchrotron based x-ray diffraction of Ni-Cr based alloys has been done to quantify the phase fraction of Ni2Cr from isothermal ageing conditions. Four model Ni-Cr based alloy in Ni to Cr ratio 1.8, 2.0, 2.2, and 2.4, and three commercial Ni-Cr based alloy 625, 625P, and 690 were characterized with this method. The isothermal ageing temperatures were 360, 418, and 470 [°C]. The isothermal ageing times were as received, 500, 1000, 3000, 5000, 10000, and 17000 [hrs]. The change in lattice parameter can indicate that a phase transformation is occurring. A disorder-order phase transformation can cause the lattice to contract. One such phase transformation of this kind is long range ordering, specifically of interest to the alloys studied is Ni2Cr. The Ni2Cr phase is associated with embrittlement, and degradation of the alloy. In preliminary results these alloys show the Ni2Cr phase is present.