Advances in Ferrous Metallurgy: AHSS and Steelmaking Process Innovation
Sponsored by: AIST Metallurgy — Processing, Products & Applications Technology Committee
Program Organizers: Siddhartha Biswas, Big River Steel; Daniel Baker, LIFT; Lijia Zhao, Northeastern University
Tuesday 8:00 AM
October 11, 2022
Room: 405
Location: David L. Lawrence Convention Center
Session Chair: Daniel Baker, LIFT
8:00 AM Cancelled
Difference in Deformation-induced Martensitic Transformation Behavior at Tensile and Compressive Deformations of High-carbon Bainitic Steel Investigated by In Situ Neutron Diffraction: Rintaro Ueji1; Wu Gong2; Stefanus Harjo2; Takuro Kawasaki2; Akinobu Shibata1; Yuuji Kimura1; Tadanobu Inoue1; Noriyuki Tsuchida3; 1National Institute for Materials Science; 2Japan Atomic Energy Agency; 3University of Hyogo
Deformation induced martensitic transformation (DIMT) during tensile or compressive deformation in the high carbon bainitic steel (0.62wt%C-2.02%Si-0.23%Mn-1.01%Cr-Fe) was studied. The microstructure before the deformation was bainite with the retained austenite whose volume fraction was 35%. The tensile deformation accompanied with the large work hardening; whereas the compression test showed the less. This was due to the suppression of DIMT at the compressive stress, which was confirmed by both measurements of the electron back scattering diffraction (EBSD) and the in situ neutron diffraction. It was also found that increasing of the lattice strain at austenite phase by tensile deformation retarded with the DIMT while this retardation was not found at the compression. This result indicates the significant change of internal stress condition depending on the stress polarity.
8:20 AM
Effects of Cyclic Intercritical Annealing on Retained Austenite in Medium Manganese Steels: Dawn Van Iderstine1; Matthew Cagle1; Shiraz Mujahid1; YubRaj Paudel1; Sven Vogel2; Zackery McClelland3; Robert Moser3; Haitham El Kadiri4; Hongjoo Rhee1; 1Mississippi State University, Center for Advanced Vehicular Systems; 2Los Alamos National Laboratory, Materials Science and Technology Division; 3U.S. Army Engineer Research and Development Center, Geotechnical and Structures Laboratory; 4Mississippi State University, Department of Mechanical Engineering
Intercritically annealed medium manganese steels are a promising third-generation advanced high-strength steel candidate. Through manganese enrichment of austenite, large austenite fractions (>30%) can be retained at room temperature, allowing for transformation-induced plasticity during deformation to prolong work hardening through high strains. Prior studies have established strong mechanical property dependence on the amount and stability of this retained austenite. However, austenite distribution – which is key given the role of ductile austenite in mitigating strain incompatibility between hard ferrite grains – has received less attention. To promote widespread austenite distribution, a novel cyclic intercritical annealing has been designed to encourage austenite nucleation while limiting its growth. Preliminary experimentation, including tensile testing, neutron diffraction, and microstructure analysis, indicates that the cyclic heat treatment promotes nucleation and efficient stabilization of austenite. Additionally, the effects of the thermal cycle on austenite formation, stability, and distribution are analyzed and compared against equivalent isothermal annealing.
8:40 AM
Mechanical Behavior and Plasticity Mechanisms of Ultrahigh Strength-high Ductility 1 GPa Low Density Austenitic Steel with Ordered Precipitation Strengthening Phase: Craig Guerrero1; Devesh Misra1; 1University of Texas at El Paso
We describe here the mechanical behavior and plasticity mechanisms of Fe-27Mn-9Al-1C austenitic steel. The experimental steel was characterized by ultimate tensile strength and elongation to fracture of 1125 MPa and 30.8%, respectively. Plastic deformation was accommodated by pronounced planar dislocation slip and characterized by a single planar dislocation glide at low strain and multiple planar slip at high strain. Electron microscopy studies indicated that some of the uniformly distributed ordered kappa carbide precipitates of size ~5–7 nm were sheared by planar glide dislocations during deformation. The planar dislocation glide phenomenon is attributed to the superposition of sheared ordered phase and short range ordering (SRO), which can lead to glide plane softening. Dynamic slip band refinement and shearing of precipitates led to constant strain hardening of austenitic steel. Annealing twin boundaries acted as dislocation source to generate dislocations during deformation, which facilitated sub-division of slip bands and suppressing strain localization.
9:00 AM
Relationship between Hardness Distribution and Microstructure Formation Process during Martensitic Transformation in Steels: Jiro Okumo1; Shoichi Nambu1; 1University of Tokyo
Since the local harness in martensitic steels is widely distributed, in this study, the relationship between local harness distribution and microstructure formation process during martensitic transformation was investigated by combining hardness evaluation and in-situ observation. Steels with different carbon contents (0.002C and 0.12C, in mass%) were prepared. The formation process was observed by a confocal laser microscopy, the crystal orientation for observed area was analyzed by EBSD, and the micro Vickers hardness test was also conducted. For 0.002C steel, coarse blocks were observed and each block was formed to expand gradually. In each block, the hardness of area where it was formed initially is low. For 0.12C steel, a single block formed to divide austenite grain in the early stage of transformation, and multiple blocks were generated simultaneously in the later stage to form a packet. In each austenite grain, the local harness increased as the formation temperature decreased.
9:20 AM
Structure-property Relationship of High Mn Steel and Bi-metallic Hammers for Clinker Crusher Application: Abhinav Karanam1; Arnab Sarkar2; Erik Nenzen2; Lukas Bichler2; 1Unicast Inc; 2University of British Columbia
The present work focuses on the comparative investigation of structure-property relationship between high Mn steel and bi-metallic hammers for clinker crusher application. Our earlier studies reported that high Mn steel witnesses severe embrittlement at ambient temperatures. The low thermal stability of high Mn steel at different temperatures has been the primary cause for the in-service failure of clinker crushers operations. In contrast, cladding of alloy steel with white cast iron for bimetallic hammers are potentially more capable for clinker crusher application when they are subjected to temperatures ranging within 250 - 500ºC. The microstructures reveals the constituents of transformed phases and its distribution along with the variation in grain sizes at different temperatures. The changes in microstructural features are further correlated to results of unnotched Charpy impact testing and wear testing that suggest the bimetallic hammers with distinct interfacial transition layers could be considered as candidate materials for this application.
9:40 AM Cancelled
Novel Tough Ultrahigh Strength Steels Through Direct Quenching and Partitioning Route – A Status Report: Mahesh Somani1; Sumit Ghosh1; Pekka Kantanen1; Devesh Misra2; Jukka Kömi1; 1University of Oulu; 2University of Texas at El Paso
Ever since the establishing of TMR-DQP processing route for the development of tough, ductile, ultrahigh-strength steels with yield strengths >1100 MPa, significant progress has been made at the authors’ laboratory to extend the processing route to medium carbon steels with special emphasis on employing physics-based physical metallurgy concepts to realize excellent combination of properties. The processing route comprises thermomechanical rolling followed by direct quenching and partitioning (TMR-DQP) with resulting microstructures normally consisting of two or more finely divided phases. The key research strategy encompassed studying structural refinement approaches, phase transformation characteristics, and accompanying microstructural mechanisms using advanced metallography as well as analytical techniques including atom probe tomography. The accomplishment of reasonable ductility and high toughness with these complex microstructures has been characterized in respect of associated deformation and fracture mechanisms. The paper presents an account of the current status of the research, development, design, and processing of DQP steels.
10:00 AM
Flow Optimization for Steel Refining Process in an EAF: Neel Busa1; Yuchao Chen1; Armin Silaen1; Bikram Konar2; Chenn Zhou1; 1Purdue University Northwest; 2EVRAZ NA
An Electric Arc Furnace is a method in steelmaking, used to remove impurities from steel scrap. The process starts with melting of the solid scrap with a coherent jet burner, followed by mixing via oxygen injection into the bath. The homogenous stirring of the bath plays a vital role in the steel refining process as it ensures removal of impurities and further improves the quality of liquid steel. The current study helps to dynamically predict the details of the bath and provide significant solutions to optimize the flow. The focus of the study is propose parametric studies based on initial results, in order to further improve the mixing in the domain. Preliminary results indicate better mixing of the bath is owed to velocity distributions in regions near the injection cavities, and making these distributions uniform for the entire bath should give optimum flow results.