Pan American Materials Congress: Advanced Manufacturing: Metals and Alloys
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Sonia Brühl, UTN - National University of Technology; Ricardo Castro, University of California, Davis; Dachamir Hotza, UFSC

Tuesday 3:40 PM
February 28, 2017
Room: Marina D
Location: Marriott Marquis Hotel

Session Chair: Sonia Brühl, UTN; Ricardo Castro, University of California, Davis

3:40 PM  Cancelled
Overview - The Use of Plasma Nitriding for Surface Hardening Stainless Steels: Carlos Pinedo1; Andre Tschiptschin2; 1TMS; 2University of Sao Paulo
    Stainless steels are widely used for industrial applications where corrosion resistance is a key property for getting the best performance. However, for many applications the wear resistance of these steels is not enough to sustain large contact stresses when in contact with hard particles. In such cases, nitriding is an important process to increase surface hardness and wear resistance. However, the nitriding mechanism is different for each stainless steel grade, due to different starting microstructures. There are two basic mechanisms operating in the structural changes happening during the nitriding for obtaining a stainless steel case, responsible for the increase in surface hardness. The first one is the formation of expanded lattice phases: “expanded austenite”, “expanded ferrite” and “expanded martensite”. The second one is the iron and chromium nitride precipitation in the nitrided case.

4:20 PM  
Combining CALPHAD-informed Phase-field Modeling with Rapid Solidification Experiments for Prediction of Microstructure Evolution during Laser-based Additive Manufacturing: Aurelien Perron1; John Roehling1; Patrice Turchi1; Jean-Luc Fattebert1; Joseph McKeown1; 1Lawrence Livermore National Laboratory
     The coupling of phase-field modeling (PFM) to thermodynamic and kinetic databases (CALPHAD methodology) is important for realistic parameterization of PFM. The present work aims at studying solidification in metallic alloys from “equilibrium” to far-from-equilibrium conditions to address the challenge of rapid-solidification processes encountered during laser-based additive manufacturing (AM). Modeling successes and challenges will be discussed and compared with experimental data. Experiments consist of laser surface melting and re-solidification in bulk alloys and in situ laser melting and rapid solidification in thin-film alloys. The latter approach, conducted in the dynamic transmission electron microscope (DTEM), permits to track the kinetics of the solidification front, and to monitor the microstructure evolution during solidification.This work was performed under the auspices of the U.S Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Work at LLNL was funded by the Laboratory Directed Research and Development Program under project tracking code 15-ERD-006.

4:40 PM  
Tailoring the Mechanical Properties of Additively Manufactured Ti-6Al-4V Alloys by Post Processing: Guney Mert Bilgin1; Ziya Esen2; Seniz Kushan Akin2; Arcan Dericioglu1; 1Middle East Technical University; 2Cankaya University
    Additive manufacturing (AM) is a raising production technology for the applications of Ti-6Al-4V alloy where complex geometrical and unconventional structural designs are required. Selective laser melting is a promising AM technique based on complete melting of Ti-6Al-4V providing near net shaping with relatively high density. However, because of some process drawbacks, like large thermal gradients and short interaction times, segregation and formation of non-equilibrium α' phase become an issue. The resulting α' microstructure has a negative impact on the mechanical properties and leads to poor ductile performance. In this study, various post processing methods such as hot isostatic pressing, thermohydrogen processing and several heat treatments were performed to satisfy the mechanical norms required by the aerospace applications. Tensile and compressive properties were evaluated along with microstructural progress. Finally, initially present α' phase containing microstructure were transformed to a refined microstructure composed of α+β grains and mechanical properties were improved.

5:00 PM  
Effect of Tool Rotation on Tool Wear Phenomenon in Rotary Tool micro-USM: Sandeep Kumar1; Akshay Dvivedi1; Pradeep Kumar1; 1Indian Institute of Technology, Roorkee
    Micro-USM is used to fabricate complex micro-features in all brittle & hard materials. In micro-USM, both dimensional and form accuracy of machined component are depend on the shape of the tool & geometry. During machining, tool wear is an unavoidable phenomenon of micro-USM, which affect the accuracy of micro-feature. This article reports on a method named as rotary tool micro-USM to reduce tool wear. The rotary tool micro-USM involves abrasive slurry with providing simultaneous rotation and vibration to the tool. Rotation of the tool helped abrasives to replenish from the machining gap easily. Micro-channels were fabricated and characterized by using stereo microscope. From the results, it was found that rotary tool micro-USM resulted in very less tool wear and as a result of that micro-channels of better dimensional and form accuracy were developed.

5:20 PM  
Green Machining Process: Near-dry Electric Discharge Machining: Krishnakant Dhakar1; Kuldeep Chaudhary1; Akshay Dvivedi1; Pradeep Kumar1; 1Indian Institute of Technology Roorkee