Characterization of Minerals, Metals, and Materials: Material Processing and Corrosion
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Shadia Ikhmayies, Al Isra University; Bowen Li, Michigan Technological University; John Carpenter, Los Alamos National Laboratory; Jian Li, CanmetMATERIALS; Jiann-Yang Hwang, Michigan Technological University; Sergio Monteiro, Military Institute of Engineering ; Firrao Donato, Collegio Universitario, Italy; Mingming Zhang, ArcelorMittal Global R&D; Zhiwei Peng, Central South University; Juan P. Escobedo-Diaz, UNSW Australia; Chenguang Bai, Chongqing University; Eren Kalay, METU; Ramasis Goswami, Naval Research Laboratory; Jeongguk Kim, Korea Railroad Research Institute

Wednesday 2:00 PM
March 1, 2017
Room: 31B
Location: San Diego Convention Ctr

Session Chair: Jian Li, CanmetMATERIALS; Brett Sanborn, Sandia National Laboratories

2:00 PM  
Optimizing Polishing Parameters of Chemical Mechanical Planarization for C-plane (0001) GaN Using Taguchi-based Grey Relational Analysis: Khushnuma Asghar1; Tanjore Jayaraman2; Dibakar Das1; 1University of Hyderabad, India; 2University of Michigan - Dearborn
    In this investigation we adopted the Taguchi-based Grey Relational Analysis approach in order to optimize the chemical mechanical planarization (CMP) process-parameters of c-plane GaN in a potassium-permanganate/alumina (KMnO4/Al2O3) slurry. The design of experiments was based on a Taguchi orthogonal array L18 (21 x 37) to determine the optimal setting of the CMP process-parameters: slurry pH, KMnO4 concentration, Al2O3 wt. %, down-pressure, and platen RPM. The Material Removal Rate (MRR) and Surface Roughness (RMS) were considered as the criteria for optimization and, the optimum process conditions provided a grey relational grade (GRG) as high as ~0.86. The influence of the process-parameters on GRG can be summarized as: slurry pH > down-pressure > platen RPM > Al2O3 wt. % > KMnO4 concentration. This study showed that for CMP of c-plane GaN in KMnO4/Al2O3 slurry, the lowest RMS that can be reached while maintaining a reasonably high MRR (~142 nm/h) is ~22 nm.

2:20 PM  
Corrosion Behavior of Super-Ferritic Stainless Steels in NaCl Media: Natalia Zadorozne1; Alicia Ares2; Raśl Rebak3; 1IMAM (CONICET-UNaM); 2CONICET/FCEQyN-UNaM; 3GE Global Research
     The electrochemical behavior of APTM (Fe–21Cr–5Al–3Mo–0.04C) and 4C54 (Fe–26.5Cr–0.8Mn-0.5Si) super-ferritic stainless steel in NaCl solutions has been studied using open circuit potential measurements, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. The aim is to compare the behavior of these materials with austenitic stainless steel alloy 316 (Fe-18Cr-10Ni-2.5Mo). The results indicate that the APTM alloy presents a better performance than the alloy 316, while 4C54 not, especially in regions of anodic potential. This behavior may be due to Al and Mo content in the APTM composition.

2:40 PM  
Influence of Corrosion on Dynamic Tensile Properties of 304 and 304L Stainless Steel: Brett Sanborn1; Eric Hicks1; Bo Song1; Miguel Atencio1; 1Sandia National Laboratories
    Formation of oxides on metals over time results in pits or cracks that eventually lead to decreased mechanical performance. This cost of corrosion has been estimated to be as high as $500 billion annually in the US. Understanding the effect of corrosion on mechanical properties is an important step in characterizing possible decrease to mechanical performance of in-service equipment or components that may undergo impact loading. While corrosion fatigue in the quasi-static regime has been well studied, the effect of corrosion on high strain rate material properties has been less investigated. In this study, non-corroded and corroded 304 and 304L stainless steel samples were subjected to high strain rate tensile loading to explore the effect of surface corrosion on the dynamic tensile properties.

3:00 PM  
Characterization of Recrystallization and Twin Evolution Mechanisms Using In Situ TEM: Asher Leff1; Austin Nye1; Ryan Demott1; Mitra Taheri1; 1Drexel University
    Thermomechanical processing can be utilized in order to control the grain boundary character of structural metals in order to optimize performance. In particular, the generation of interconnected twin and twin-related boundary networks has been shown to enhance the properties of FCC metals. This study utilized in situ heating and electron microscopy orientation mapping techniques at multiple length scales in conjunction with the analysis of orientation data in order to examine the evolution of twin-related domains in copper and brass during recovery, primary recrystallization and secondary recrystallization processes. Dislocation densities were quantified using local misorientation analysis in order to determine the driving force thresholds for these processes. Copper was chosen as a model FCC material and 90/10 brass was used to examine how substitutional solutes change the stored energy requirements for the activation of various mechanisms. Twin nucleation rates were found to be independent of recrystallization rates regardless of solute content.

3:20 PM  
Effect of Bromide Ions on the Pitting Corrosion of Hafnium in Anhydrous T-butanol and Acetonitrile: Chang Hong Wang1; Shenghai Yang1; Yongming Chen1; Xiyun Yang1; Yanzeng Wu1; Jing He1; Chaobo Tang1; 1Central South University
    Pitting of Hf in Et4NBr t-butanol and acetonitrile(ACN) solutions was studied by means of cyclic voltammetry, potentiodynamic anodic polarization, galvanostatic, potentiostatic and impedance techniques. The potentiodynamic anodic polarization curves did not exhibit an active dissolution region near corrosion potential due to the presence of an oxide film on the electrode surface, which was followed by pitting corrosion resulting from the passivity breakdown by the aggressive attack of bromide (Br-) ion. The pitting potential (Epit) increased with increasing potential scanning rate but decreased with increasing temperature and Br- concentration. Cyclic voltammetry and galvanostatic measurements allowed the pitting potential (Epit) and the repassivation potential (Ep) to be determined. The current/time transients indicated that the incubation time (ti) for passivity breakdown decreased slightly with increasing potential and solution temperature. The impedance spectra showed that the resistance of passive layer decreased with increasing potential.

3:40 PM Break

3:55 PM  
Compression Behavior of Semi-Closed Die Forged AZ80 Extrusion: Andrew Gryguc1; Sugrib Shaha1; Hamid Jahed1; Mary Wells1; Bruce Williams2; Jonathan McKinley2; 1University of Waterloo; 2CanmetMATERIALS
    Warm forging to near net shape shows promising benefits in terms of microstructure refinement and texture modification. In the present study, compression tests were performed to investigate the influence of forging at a deformation rate of 0.4 mm/s and a temperature of 400°C on the performance of extruded AZ80 magnesium alloy. The obtained microstructural analysis showed that the extruded AZ80 magnesium alloy possesses typical wrought grain structure with sharp texture. In contrast, the forged samples showed refined grains and a variation of texture from stronger to weak depending on the location of the sample. The monotonic compression results in the extrusion direction showed that the forged sample obtained a maximum strength and ductility of 446 MPa and 0.13, respectively which was higher than the as-extruded materials at the same orientation. It is believed that forging causes grain refinement and texture modification which enhance the alloy performance.

4:15 PM  Cancelled
Dislocation Densities Evolution and Similitude Behavior from Severe Plastic Deformation in Machining: Sepideh Abolghasem1; Saurabh Basu2; M. Ravi Shankar3; 1Universidad de los Andes; 2Georgia Institute of Technology; 3University of Pittsburgh
    Evolution in microstructure of materials undergoing plastic deformation happens through multiplication and storage of dislocations. Samples of commercially pure copper are deformed using large strain orthogonal machining and dislocation densities are measured using peak profile broadening analysis using X-ray diffraction (XRD). It is shown that the average total dislocation densities resulting from this deformation correlate with the strain and the average subgrain-size. From this, a suitably parameterized map-space is proposed for capturing the average dislocation densities resulting from severe shear deformation. The parameterization is characterized by the y axis as the strain and the x axis as a parameter R, which is a function of the strain-rate, temperature and material constants. Using the values of interior dislocation densities and the average subgrain-size the results for “Principle of Scaling” or similitude are shown which is in agreement with literature.

4:35 PM  
Fatigue Fracture Surface Morphologies in Controlled Crack Growth Rail Steel Specimens: Donato Firrao1; Roberto Doglione1; Paolo Matteis1; Stefano Rossi2; Raffaella Sesana3; 1Politecnico di Torino - DISAT; 2Rete Ferroviaria Italiana SpA; 3Politecnico di Torino - DMEAS
    Fatigue fracture surfaces of R260 rail steels have been examined and their morphology interpreted at the light a micro-mechanical model previously developed by the authors. Rail steels have an almost complete pearlite structure, for which the model calls for a rupture of cementite lamellae when the crack tip approaches a pearlite colony leaving a network of ferrite platelets to stand the incoming cyclic stress/strain field. Depending on the crack growth rate, a single resisting ferrite lamella, already strained and cross area reduced by the incoming stress concentration, can be overcome in a single jump or in a few cycles of the fatigue process. Tests with varying da/dN values have been performed on rail steels samples under different applied ΔK’s. Fatigue fracture morphologies and the application of the above reported model to the present case have been related with Paris Law curves pertaining to the examined type of steel.

4:55 PM  
Nondestructive Characterization of Microstructures of Heat-Treated Steels by Magnetic Barkhausen Noise Technique: C. Hakan Gur1; 1Ankara
    Optimization and control of the microstructure is important for improving the properties of steel components. Development of non-destructive techniques for microstructure characterization is a critical task. Magnetic Barkhausen Noise (MBN) technique is a promising and challenging non-destructive technique for automated evaluation of microstructures in steel components in a fast and reliable manner. This paper presents the results of MBN measurements for microstructure characterization of the quenched and tempered steels.

5:15 PM  
Automated Optical Characterization of Inconel 100 Using Computational Microstructural Toolsets: Sundar Veeraraghavan1; Satya Ganti1; Bryan Turner1; Brian Hayes1; John Porter1; Dennis Dimiduk2; Michael Jackson2; Michael Uchic3; 1UES, Inc; 2BlueQuartz Software, LLC; 3Air Force Research Laboratory
    Emulating microstructure–property relationships requires 3-dimensional (3D) models of microstructure. Automated serial sectioning methods such as Robo-Met.3D make 3D datasets more readily obtainable, but data-to-models workflows for specific characterization needs are still emerging. In this study we use mechanical serial sectioning to examine nickel alloy (IN-100) samples having varying processing history. The DREAM.3D open source tool set, and other state-of-the-art software tools, are used to build a workflow for image quantification. The workflow focuses on grain size and ALA grain features in 3D. The talk emphasizes current capabilities and highlights needed improvements for gray-scale image quantification.