High Performance Steels: On-Demand Oral Presentations
Sponsored by: TMS Structural Materials Division, TMS: Steels Committee
Program Organizers: Ana Araujo, Vesuvius USA; C. Tasan, Massachusetts Institute of Technology; Jonah Kleem-Toole, Colorado School of Mines; Louis Hector, General Motors Global Technical Center; Tilmann Hickel, Bam Federal Institute For Materials Research And Testing; Benjamin Adam, Oregon State University

Monday 8:00 AM
March 14, 2022
Room: Advanced Materials
Location: On-Demand Room


Small-scale Rapid Alloy Prototyping of Extra-low Carbon Steel to Investigate the Effects of Cu and Cr Residuals: Mazher Ahmed Yar1; Caroline Norrish1; Jonathan Cullen1; Lintao Zhang1; Nicholas Lavery1; Stephen Brown1; Richard Underhill2; 1Swansea University; 2Tata Steel
    A small-scale, rapid alloy prototyping (RAP) route is presented for accelerated lab-scale development of an array of steels across many applications in which alloys can be tailored with individual or combined elements to a compositional precision down to 0.1%. At the level of 40g, over twenty unique compositions can be manufactured and validated in a week, with the process including compacting and melting raw materials, casting into a bar, followed by rolling and heat treatment. A specific application of RAP is presented whereby incremental additions of residual elements, in this instance Cu and Cr, are added to an ultra-low carbon steel with the aim of understanding the effects of increased scrap recycling on the final product properties. ASTM tensile test results are discussed reflecting the effects of seven levels of Cu and Cr, up to 36 times the current industrial limits, showing the versatility of this RAP route.

Design and Characterization of Abrasion-resistant Steel Coatings for Nuclear Industry: Lisa Rateau1; Franck Tancret2; Anna Fraczkiewicz3; Jean Dhers1; Gérard Ramstein4; 1Framatome; 2Institut des Matériaux Jean Rouxel; 3Laboratoire Georges Friedel; 4Laboratoire des Sciences du Numérique de Nantes
    In order to prevent the activation of 60Co cobalt particles in the primary circuit of nuclear reactors, it is necessary to replace cobalt-based alloys of the Stellite type, used as abrasion-resistant coatings, with cobalt-free alloys. No material tested so far displays equivalent properties. In this work, both machine learning and CALPHAD (Calculation of Phase Diagrams) thermodynamic models were used to calculate microstructure and performance criteria, and exploited by a multi-objective genetic algorithm to design abrasion-resistant steels. Some of them have been elaborated and characterized (SEM, XRD, TEM, EBSD, mechanical testing…) to verify the agreement between predictions and actual microstructure and properties. Notably, measured hardness and wear resistance fit with data mining models, and these steels have a better abrasion resistance than Stellite alloys. To verify the compatibility with nuclear industry requirements, high temperature mechanical properties have been measured.

Design and Challenge of Cold-rolled Dual-phase Steel Strengthened by Interphase Precipitation: Shao-Lun Lu1; Kuo-Cheng Yang2; Ching-Yuan Huang2; Hung-Wei Yen1; 1National Taiwan University; 2China Steel Corporation
    In this work, design of cold-rolled dual-phase (DP) steel with interphase precipitation via CALPHAD is demonstrated. Coarsening of carbides is the primary barrier for production of cold-rolled DP steel with nanometer-sized carbides. We design a novel process of DP steel to dissolve carbides and form interphase-precipitated carbide in the annealing, enabling strengthening of ferrite by nanometer-sized carbides. Besides, phase transformation characteristics at various temperatures were determined by thermodynamics. Distribution of nanometer-sized carbides was investigated by using transmission electron microscopy. Contributed strength from carbides was evaluated by hardness test. Although alloy design by CALPHAD solves coarsening issue, it is interesting that banded structure due to segregation appears to be the new challenge. In summary, this study delivers discussion on the solved and unsolved issues in design of cold-rolled dual-phase (DP) steel with nanometer-sized carbides.

Hydrogen Embrittlement Susceptibility of a High Manganese Twinning Induced Plasticity Steel Examined via Correlative Microscopy: Heena Khanchandani1; Leigh Stephenson1; Dierk Raabe1; Stefan Zaefferer1; Baptiste Gault1; 1Max Planck Institute for Iron Research
    Twinning induced plasticity (TWIP) steels are promising structural materials, belonging to a class of high manganese steels having austenite phase with face centred cubic crystal structure. Several studies have been carried out to understand the hydrogen embrittlement mechanism in TWIP steels [An et al., Int J Plast 2019]. Yet, the actual prevalent mechanism is not fully understood. We present our studies based on the hydrogen embrittlement susceptibility of a model TWIP steel Fe 28Mn 0.3C (Wt. %) alloy which was cold rolled and subsequently recrystallized. The studied TWIP steel sample was cathodically charged with hydrogen for 5 days and subjected to the tensile tests. The microstructural evolution was examined with and without hydrogen precharging at different stages of tensile deformation, using electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) techniques. It was observed that the dislocation arrangement changes after hydrogen charging at different stages of the tensile deformation.

Simultaneous Enhancement of Hardness and Corrosion Resistance in Carbide-reinforced Martensitic Steels: Kenta Yamanaka1; Haruka Shima1; Manami Mori2; Kazuo Yoshida1; Yusuke Onuki3; Shigeo Sato3; Akihiko Chiba1; 1Tohoku University; 2National Institute of Technology, Sendai College; 3Ibaraki University
    High-speed steels, which comprise martensitic matrices and fine carbide precipitates, exhibit excellent wear resistance. However, the high fraction of carbide precipitates causes severe dissolution of the martensitic matrix in corrosive medium. Recently, we revealed that adding trace Cu significantly improves the corrosion resistance of such steel grades. In this study, to optimize the alloy design, we examined the effects of composition and heat treatments on the hardness and corrosion resistance of the alloys. The alloy’s hardness increased monotonously with increasing the carbon content. Using quantitative microstructural analyses based on neutron diffraction measurements, we demonstrated that the hardness of such steels originates dominantly from the increased dislocation density in the carbon enriched martensitic matrix rather than the volume fraction of carbides. In combination with the potentiodynamic polarization tests, an optimal composition was determined for enhanced corrosion resistance without severe degradation of corrosion resistance.

Understanding Deformation-induced Cracking in Dual-phase Steel via the Combination of EBSD Analysis and Convolutional Neural Network: Hung-Wei Yen1; Po-Hsun Lin1; Yi-Fan Hu1; Min-Yu Tseng1; Kuo-Cheng Yang2; Kangying Zhu3; 1National Taiwan University; 2China Steel Corporation; 3ArcelorMittal
     Dual-phase (DP) steel has been widely used in vehicles due to its excellent strength-ductility balance. However, micro-cracks could be induced during cold forming, leading to unqualified components. The study on formation of micro-crack in DP steel is a long history and primary factors are attributed to chemical composition, loading mode, strength grade, and phase constituent. Until today, the principles of micro-cracking are not yet unified. In this work, we developed a state-of-art algorithm by convolution neural network to predict crack formation from EBSD analysis. Machine learning and analyses were done for DP steels from 590 MPa grade to 1180 MPa grade. The essentials of cracking sites for DP steels of various grades are classified based on phase constituent. Moreover, we developed an approach to predict crack propagation from the learning results. The research will contribute on the microstructural design to optimize formability of DP steels.

Phase Field Simulations of Microstructure Evolution during Rapid Thermal Processing of High Strength Steels: Bala Radhakrishnan1; Gary Cola2; 1Oak Ridge National Laboratory; 2Flash Steelworks, Inc.
    High strength steels with exceptional combinations of strength and ductility have been obtained through a rapid thermal cycling process, designated as Flash® annealing. The exceptional properties are obtained through the formation of a heterogeneous microstructure consisting of an inhomogeneous distribution of bainite, martensite and retained austenite after Flash® annealing. The distribution of these constituents in the processed microstructure is determined by the solute concentration gradients that develop due to carbide dissolution, and austenite nucleation and growth during rapid thermal cycling. We present high-resolution, three-dimensional, phase field simulations that quantify the effect of the initial microstructure and processing conditions on the development of solute concentration gradients. Research sponsored by the Advanced Manufacturing Office of the U.S. Department of Energy under the High-Performance Computing for Energy Innovation (HPC4EI) program and performed at the Oak Ridge National Laboratory managed by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy.

Characterization of a Complex-phase Steel by Electron Backscattering Diffraction and Atomic Force Microscopy: Renan Lima1; Julio Spadotto2; Flávia Tolomelli3; Omar Pandoli1; Fernando Rizzo1; 1PUC-Rio; 2PUC-Rio / University of Manchester ; 3CSN
    Advanced High Strength Steels (AHSS) are in high demand in the automotive industry. New and improved steels are needed to increase the resistance and reduce the weight of vehicles. The replacement of traditional dual-phase (DP) by Complex-Phase (CP) steels, more resistant and less prone to void nucleation, is an interesting perspective; one way to improve their mechanical properties is to better control their microstructure. The microstructural characterization of CP steels is hard but has been consistently performed using Electron Backscattering Diffraction (EBSD). However, EBSD analysis takes time, can be costly and the sample preparation is usually a challenge. Recently, a newly produced complex-phase steel was characterized by EBSD and Atomic Force Microscopy (AFM). The AFM characterization was much faster and cheaper, with a simpler sample preparation method. In this work, the comparison between the two characterization methods, their advantages, and challenges are reported.

Microstructural Engineering in Dual Phase Steels -Partitioning Aspects and Correlation to Formability: Soudip Basu1; Anirban Patra1; B.N. Jaya1; Sarbari Ganguly2; Monojit Dutta2; Indradev Samajdar1; 1Indian Institute of Technology, Bombay; 2Tata Steel limited, Jamshedpur
    Dual phase (DP) steels, a functional example of advanced high strength steels, are heavily employed in the automobile industry where high formability becomes a prerequisite. Improving formability directly correlates to delaying failure under complex stress fields, in other words post-necking ductility. This requires an understanding of the partitioning behavior of stresses, strains and triaxialities at a microstructural level. A combination of experiments and simulations have been used to predict the effect of microstructural variables like phase hardness differential, martensite volume fraction and size on the partitioning characteristics of DP, and their concurrent effect on the strength-ductility optimization. The knowledge obtained from such studies is used to generate and validate microstructures with desirable formability. This microstructural engineering approach can thus be used to obtain DP microstructures which provide enhanced partitioning and hence better resistance to failure during their manufacturing and service.

Early Stages of Liquid-metal Embrittlement in an Advanced High-strength Steel: Yuki Ikeda1; Renliang Yuan2; Anirban Chakraborty3; Hassan Ghassemi-Armaki4; Jian-Min Zuo2; Robert Maaß1; 1Bundesanstalt für Materialforschung und -prüfung; 2University of Illinois Urbana-Champaign; 3ArcelorMittal Global Research and Development; 4General Motors R&D, Manufacturing Systems Research Laboratory
    Despite the high strength and ductility of advanced high-strength streels (AHSS), the Zinc (Zn) coating typically applied to increase its corrosion resistance can be the origin of significant mechanical property degradation if, for example, joined with spot welding. This property degradation is a manifestation of the well-known Liquid Metal Embrittlement (LME) phenomena, during which liquified Zn infiltrates into the steel substrate along grain boundaries (GBs). In order to shed more light on the early stages of LME in AHSS, we pursue here the approach to study infiltrated but uncracked GBs. We use scanning transmission electron microscopy (STEM) to investigate these boundaries and conclude that prior to cracking nucleation and growth of intermetallic phases occurs inside the uncracked GBs. We discuss these findings in the context of resulting local strain heterogeneities that may eventually trigger microcracking in LME.

Understanding Microstructural Evolution in a Thick Gauge High Strength Niobium-microalloyed Line Pipe Steel: Monowar Hossain1; Xingshuo Wen2; Michael Mulholland2; Bertram Ehrhardt3; Steven Jansto4; Gregory Thompson1; Nilesh Kumar1; 1University of Alabama, Tuscaloosa; 2ArcelorMittal Global R&D - East Chicago; 3AM/NS Calvert AL; 4Research & Development Resources, Bowling Green OH
    For higher productivity, oil and gas are increasingly being transported at higher pressures through steel pipelines which has necessitated development of thick gauge high strength – high toughness line pipe steels. In this work, the microstructural evolution of Nb-microalloyed API Grade X70 line pipe steel has been investigated to understand microstructural variation across the thickness of the 22 mm hot-rolled steel samples from hot-band coils for spiral pipe. The microstructure of the steel sample was probed using optical microscope, scanning electron microscope, and electron backscattered diffraction to characterize different phases, grain size, grain boundary character, aspect ratio, and texture. These microstructural parameters were observed to vary across the depth of the plate. TEM analysis of the steel is performed to characterize and quantify nano-sized Nb containing precipitates. An in-depth understanding of microstructure of the steel will allow its correlation with and prediction of mechanical properties such as ductile-brittle transition temperature.