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Title: Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel

Abstract

Microstructures composed of lath martensite and retained austenite with volume fraction between 8.0 vol.% and 12.0 vol.% were obtained in a low-C low-Si Al-free steel through hot-rolling direct quenching and dynamical partitioning (HDQ&DP) processes. The austenite stabilization mechanism in the low-C low-Si Al-free steel under the special dynamical partitioning processes is investigated by analyzing the carbon partition behavior from martensite to austenite and the carbide precipitation-coarsening behavior in martensite laths combining with the possible hot rolling deformation inheritance. Results show that the satisfying retained austenite amount in currently studied low-Si Al-free HDQ&DP steel is caused by the high-efficiency carbon enrichment in the 30–80 nm thick regions of austenite near the interfaces in the hot-rolled ultra-fast cooled structure and the avoidance of serious carbides coarsening during the continuous cooling procedures. The excellent strength-elongation product reaching up to 26,000 MPa% shows that the involved HDQ&DP process is a promising method to develop a new generation of advanced high strength steel. - Highlights: • HDQ&DP processes were applied to a low-C low-Si Al-free steel. • Effective partitioning time during the continuous cooling processes is 1–220 s. • Retained austenite with volume fraction between 8.0 vol. % and 12.0 vol. % has been obtained.more » • The special austenite stabilization mechanism has been expounded.« less

Authors:
 [1];  [1]; ; ;  [1];  [2];  [1]
  1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China)
  2. Ceri Long Product Co., Ltd., Beijing 100176 (China)
Publication Date:
OSTI Identifier:
22476094
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 104; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITE; AVOIDANCE; EFFICIENCY; ELONGATION; INTERFACES; MARTENSITE; MECHANICAL PROPERTIES; MICROSTRUCTURE; PARTITION; PRECIPITATION; PRESSURE RANGE MEGA PA; ROLLING; STABILIZATION; STEELS

Citation Formats

Tan, Xiao-Dong, Xu, Yun-Bo, E-mail: yunbo_xu@126.com, Yang, Xiao-Long, Hu, Zhi-Ping, Peng, Fei, Ju, Xiao-Wei, and Wu, Di. Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel. United States: N. p., 2015. Web. doi:10.1016/J.MATCHAR.2015.03.022.
Tan, Xiao-Dong, Xu, Yun-Bo, E-mail: yunbo_xu@126.com, Yang, Xiao-Long, Hu, Zhi-Ping, Peng, Fei, Ju, Xiao-Wei, & Wu, Di. Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel. United States. doi:10.1016/J.MATCHAR.2015.03.022.
Tan, Xiao-Dong, Xu, Yun-Bo, E-mail: yunbo_xu@126.com, Yang, Xiao-Long, Hu, Zhi-Ping, Peng, Fei, Ju, Xiao-Wei, and Wu, Di. Mon . "Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel". United States. doi:10.1016/J.MATCHAR.2015.03.022.
@article{osti_22476094,
title = {Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel},
author = {Tan, Xiao-Dong and Xu, Yun-Bo, E-mail: yunbo_xu@126.com and Yang, Xiao-Long and Hu, Zhi-Ping and Peng, Fei and Ju, Xiao-Wei and Wu, Di},
abstractNote = {Microstructures composed of lath martensite and retained austenite with volume fraction between 8.0 vol.% and 12.0 vol.% were obtained in a low-C low-Si Al-free steel through hot-rolling direct quenching and dynamical partitioning (HDQ&DP) processes. The austenite stabilization mechanism in the low-C low-Si Al-free steel under the special dynamical partitioning processes is investigated by analyzing the carbon partition behavior from martensite to austenite and the carbide precipitation-coarsening behavior in martensite laths combining with the possible hot rolling deformation inheritance. Results show that the satisfying retained austenite amount in currently studied low-Si Al-free HDQ&DP steel is caused by the high-efficiency carbon enrichment in the 30–80 nm thick regions of austenite near the interfaces in the hot-rolled ultra-fast cooled structure and the avoidance of serious carbides coarsening during the continuous cooling procedures. The excellent strength-elongation product reaching up to 26,000 MPa% shows that the involved HDQ&DP process is a promising method to develop a new generation of advanced high strength steel. - Highlights: • HDQ&DP processes were applied to a low-C low-Si Al-free steel. • Effective partitioning time during the continuous cooling processes is 1–220 s. • Retained austenite with volume fraction between 8.0 vol. % and 12.0 vol. % has been obtained. • The special austenite stabilization mechanism has been expounded.},
doi = {10.1016/J.MATCHAR.2015.03.022},
journal = {Materials Characterization},
number = ,
volume = 104,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}
  • Here, the influence of partitioning temperature on microstructural evolution during quenching and partitioning was investigated in a 0.38C-1.54Mn-1.48Si wt.% steel using Mössbauer spectroscopy and transmission electron microscopy. η-carbide formation occurs in the martensite during the quenching, holding, and partitioning steps. More effective carbon partitioning from martensite to austenite was observed at 450 than 400°C, resulting in lower martensite carbon contents, less carbide formation, and greater retained austenite amounts for short partitioning times. Conversely, greater austenite decomposition occurs at 450°C for longer partitioning times. Lastly, cementite forms during austenite decomposition and in the martensite for longer partitioning times at 450°C.
  • Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterionmore » (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully.« less
  • DoD adopted. This specification is under the jurisdiction of ASTM Committee A-1 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A05.19 on Steel Sheet and Strip. Current edition approved Jun. 10, 1998 and published September 1998. Originally published as A 607-70. Last previous edition was A 607-96.
  • Neutron diffraction is an effective tool for mapping lattice strain distributions, from which the anisotropy of residual stress can be estimated. One of the advantages of neutron diffraction over X-ray diffraction in strain measurements lies in its deep penetration depth in most engineering materials, so strain information can be accessed throughout the thickness of a component. In addition, measurements can be made in transmission as well as in reflection so that any strain distribution in the fixed sample coordinate system may be obtained by reorienting the scattering vector direction. In this paper, a high-resolution neutron diffractometer was used to investigatemore » the strain distribution for a number of (hkl) planes in a cold rolled austenitic stainless steel. Polycrystalline models, based on the Reuss, Voigt and Hill assumptions, respectively, were employed to derive macro-stresses in the material. The experiments and analysis reveal a high crystallographic orientation-dependent anisotropy of residual stress in this material.« less