New Frontiers in Physical Metallurgy of Steels: New Frontiers in Physical Metallurgy of Steels I
Sponsored by: AIST: MPPA Committee, TMS Steels Committee
Program Organizers: Matthias Militzer, University of British Columbia; Pello Uranga, CEIT and TECNUN (University of Navarra); Jonah Klemm-Toole, Colorado School of Mines; Amy Clarke, Los Alamos National Laboratory; Amit Behera, QuesTek Innovations LLC
Wednesday 8:00 AM
October 20, 2021
Room: A210
Location: Greater Columbus Convention Center
8:00 AM Invited
Microstructural Engineering and Accelerated Test Method Development to Achieve Low Cost, High Performance Solutions for Hydrogen Storage and Delivery: Kip Findley1; John Speer1; Lawrence Cho1; Pawan Kathayat1; Yuran Kong1; Chris San Marchi2; Brian Kagay2; Samantha Lawrence3; Joseph Ronevich2; Ashok Saxena4; 1Colorado School of Mines; 2Sandia National Laboratory; 3Los Alamos National Laboratory; 4WireTough Cylinders
Hydrogen fueling infrastructure has a lack of low-cost options for storage, compressors, and dispensing components that are compatible with hydrogen. Reducing the costs could contribute to more extensive implementation of safe hydrogen fueling stations. Thus, we are designing alternative alloy options to achieve comparable hydrogen embrittlement resistance as higher cost austenitic stainless steels through analytical and computational approaches. Specifically, we are exploring both austenitic and duplex austenite-ferrite microstructures with manganese substitutions for nickel and other alloying additions to control stacking fault energy. Additionally, we are investigating microalloying approaches for grain size control, precipitation strengthening, and hydrogen trapping. Mechanical properties, including fracture toughness in hydrogen, are evaluated through in-situ electrochemical or gaseous hydrogen charging with the objective of comparing these two testing methodologies and enabling efficient and accessible accelerated testing for hydrogen embrittlement resistance. The role of alloying and microstructure on hydrogen transport and trapping is also being explored.
8:40 AM
Microstructural Modeling and Design in Triple Nano-precipitate Strengthened Austenitic Steel: Colin Stewart1; Richard Fonda2; Keith Knipling2; Patrick Callahan2; 1NRC Associate at the US Naval Research Laboratory; 2US Naval Research Laboratory
A new family of precipitate-strengthened FCC Austenitic steels stabilized by Mn additions has been developed with an integrated computational materials engineering (ICME) approach, achieving impressive hardness values over 500 HV, for an estimated yield strength of ~170 KSI. This system exhibits precipitation of three nano-scale phases upon ageing, without prior rolling steps: (i) insoluble Cu (FCC) particles; (ii) ordered intermetallic β-NiAl (B2) precipitates; and (iii) carbides. This nano-structure is observed directly by atom probe tomography (APT) across a variety of compositions and ageing times, and is modeled with ICME tools, Thermo-Calc and TC-PRISMA. This presentation will discuss the effects of composition and applied heat treatment on the observed material microstructures, and how they can be rapidly predicted by ICME tools. The microstructures will also be correlated with strengthening models, which will be compared with estimated yield strengths from experimental hardness measurements.
9:10 AM
Improving the Fatigue Performance of Nitrided Steels with Amorphous and Crystalline Precipitates: Jonah Klemm-Toole1; Kip Findley1; 1Colorado School of Mines
Nitriding is a thermochemical process where nascent nitrogen is diffused into the surface of a component at temperatures where ferrite is stable in a steel. Elevated nitrogen contents lead to solid solution strengthening as well as precipitation strengthening if nitride forming elements are present in the steel. Both solute nitrogen and precipitates result in compressive residual stresses that improve fatigue performance. In this presentation, we discuss the microstructure property relationships of a series of experimental steels that contain both crystalline MX type vanadium containing nitrides as well as amorphous precipitates that contain silicon, manganese, and nitrogen. We demonstrate that alloying to promote amorphous nitride precipitation is a novel and feasible strategy to significantly improve the fatigue performance of nitrided medium carbon steels.
9:40 AM
Obtaining High Strength Ductility Combination by Quenching and Partitioning of Rolled Low Carbon Steel Sheet: Alok Singh1; Basudev Bhattacharya2; Somjeet Biswas3; 1Indian Institute of Technology Kharagpur; 2Tata Steel Limited, India; 3IIT Kharagpur
A rolled low carbon steel sheet (C < 0.06%, Mn < 2.0%, Si < 0.5% and Cr < 1.0%) was subjected to two-step heat treatment: (i) Quenching (Q)- austenitizing at 840°C for 1 hour and water quenching followed by Partitioning (P), and (ii) P- microstructure homogenization at below intercritical temperature at 600°C for 15 minutes and followed by water quenching. Dual-phase microstructure of ferrite- 35% martensite island morphology was obtained with moderate strength of 540 MPa with very high ductility. The enhanced ductility could be associated with the presence of CSL boundaries, transformation induced plasticity due to retained austenite.