Ultra Fine-Grained 6wt% Manganese TRIP Steel

2010 ◽  
Vol 654-656 ◽  
pp. 286-289 ◽  
Author(s):  
Sea Woong Lee ◽  
Kyoo Young Lee ◽  
Bruno C. De Cooman
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
High Volume ◽  
Magnetic Saturation ◽  
Trip Steels ◽  
Fine Grained ◽  
Annealing Temperatures

Ultra-fine grained TRIP steels (UFG-TRIP) containing 6wt%Mn were produced by intercritical annealing. An ultra-fine grained microstructure with a grain size less than 1μm was obtained. The formation mechanism of the high volume fraction of retained austenite was investigated by dilatometry, XRD and magnetic saturation. The fraction of retained austenite was strongly dependent on the annealing temperature. The tensile properties were also found to be strongly influenced by the annealing temperature with poorer mechanical properties being observed at higher annealing temperatures. It was found that the stabilization of the retained austenite was both a composition and size-effect, made possible by the grain refinement due to the reversely transformed martensite.

scholarly journals The Effect of Stepped Austempering on Phase Composition and Mechanical Properties of Nanostructured X37CrMoV5-1 Steel

2015 ◽  
Vol 60 (1) ◽  
pp. 517-521
Author(s):  
S. Marciniak ◽  
E. Skołek ◽  
W. Świątnicki
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Isothermal Annealing ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
High Volume ◽  
Thin Layers ◽  
Strength Parameters ◽  
One Step ◽  
Step Heat Treatment

AbstractThis paper presents the results of studies of X37CrMoV5-1 steel subjected to quenching processes with a one-step and a two-step isothermal annealing. The TEM observation revealed that steel after one-step treatment led is composed of carbide-free bainite with nanometric thickness of ferrite plates and of high volume fraction of retained austenite in form of thin layers or large blocks. In order to improve the strength parameters an attempt was made to reduce the austenite content by use of quenching with the two-step isothermal annealing. The temperature and time of each step were designed on the basis of dilatometric measurements. It was shown, that the two-step heat treatment led to increase of the bainitic ferrite content and resulted in improvement of steel's strength with no loss of steel ductility.

Effect of Phosphorus on Microstructure, Mechanical Properties, and Formation of Retained Austenite in TRIP Steels

2012 ◽  
Vol 508 ◽  
pp. 128-132 ◽  
Author(s):  
Eui Pyo Kwon ◽  
Shun Fujieda ◽  
Kozo Shinoda ◽  
Shigeru Suzuki
Keyword(s):  
Mechanical Properties ◽  
Carbon Concentration ◽  
Trip Steel ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
The Stability

In this Study, Influences of P on the Microstructure, Mechanical Properties, and Retained Austenite Characteristics in Transformation Induced Plasticity (TRIP) Steels Were Investigated. Microstructure of 0.2mass%P Containing TRIP Steel Was Inhomogeneous and it Resulted in Deterioration of the Mechanical Properties. Retained Austenite Characteristics such as Volume Fraction and Carbon Concentration Were Also Affected by P. The Stability of Retained Austenite in P Containing TRIP Steel Was Different from that in P-Free TRIP Steel. Such Difference in the Stability of Retained Austenite Was Attributed to the Effect of the Carbon Concentration in Retained Austenite as Well as their Different Microstructure.

Microstructure and Mechanical Properties of a Lamellar-Structured Low-Alloy TRIP Steel

2021 ◽  
Vol 1016 ◽  
pp. 1188-1192
Author(s):  
Jiang Ying Meng ◽  
Zhi Geng Jia ◽  
Tong Liang Wang ◽  
Kai Fang Li ◽  
Li He Qian
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Treatment Process ◽  
Intercritical Annealing ◽  
Bainitic Ferrite ◽  
Heat Treatment Process ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
Reverted Austenite

In this paper, we report a lamellar-structured low-alloy transformation-induced plasticity (TRIP) steel; the microstructure of the steel consists of alternate lamellae of intercritical ferrite and reverted austenite on microscale, with the latter consisting of bainitic ferrite laths and retained austenite films on nanoscale. Such a microstructure was produced by a heat treatment process similar to that for producing conventional TRIP-assisted steels, i.e. intercritical annealing followed by austempering. Nevertheless, quenched martensite rather than a mixture of ferrite and pearlite was used as the starting structure for intercritical annealing to form austenite, and the resulting austenite was then transformed to bainite by austempering treatment. This steel exhibits much enhanced strength-ductility combinations as compared with those conventional polygonal-structured low-alloy TRIP steels.

Effect of Annealing Temperature on Austenite Stability of a δ-TRIP Steel

2019 ◽  
Vol 818 ◽  
pp. 82-86
Author(s):  
Xin Xu ◽  
Ren Dong Liu ◽  
Bao Yu Xu ◽  
Hong Liang Yi ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Austenite Stability ◽  
Poor Stability ◽  
Better Than

In this work, a novel type of δ-TRIP steel was designed, and the content and stability of retained austenite in δ-TRIP specimens under different annealing processes were detected and studied, respectively. The volume fraction of austenite was determined by X-ray diffraction (XRD). The microstructure and mechanical properties were analyzed systematically. The results show that a complex microstructure composed of three phases (ferrite, bainite and retained austenite) was obtained in the δ-TRIP steel. With the increasing of annealing temperature, both retained austenite and bainite content in the specimen increased, while the carbon content in retained austenite decreased, leading to a poor stability for retained austenite. Both tensile and yield strength improved with the increasing of annealing temperature, while the elongation reduced. The feature of retained austenite led to an excellent combination of ductility and strength, which was better than traditional TRIP steel.

Microstructure and Mechanical Properties of Medium Manganese Steel Plate with High Strength and Toughness

2016 ◽  
Vol 879 ◽  
pp. 2293-2299
Author(s):  
Ying Zou ◽  
Yun Bo Xu ◽  
Zhi Ping Hu ◽  
Xiao Long Yang ◽  
Xiao Dong Tan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Steel Plate ◽  
Volume Fraction ◽  
Manganese Steel ◽  
Uniaxial Tensile ◽  
Medium Manganese Steel ◽  
Strength And Toughness

An intercritical annealing process was applied to a medium manganese steel plate (Fe-0.01C-5.3Mn-1.53Si) after the thermo-mechanical controlled processing (TMCP) and ultrafast cooling (UFC). The microstructures were observed by scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The retained austenite was measured by XRD and mechanical properties were measured by uniaxial tensile and impact tests. The influence of different annealing temperature was compared and the relationship between microstructures and mechanical properties was investigated. Results showed that the microstructures of the medium manganese steel plate were characterized by ultrafine grained lath-like ferrite and retained austenite and the excellent mechanical properties could be obtained at the annealing temperature of 640°C for 5 h. The volume fraction of the retained austenite reached up to 21%, which could significantly increase the elongation compared with the traditional steel plate. The mechanical property results revealed that the steel possessed adequate ultimate tensile strength of 865MPa and excellent impact energy of 121J (-20°C). The outstanding combination of strength and toughness indicates that the steel has a bright application prospect.

scholarly journals Study on mechanical properties and microstructure of DP590 steel with different annealing process

2021 ◽  
Vol 245 ◽  
pp. 03009
Author(s):  
Libo Pan ◽  
Chengjiang Lin ◽  
Wenqiang Zhou ◽  
zhijiang Zuo
Keyword(s):  
Mechanical Properties ◽  
Aging Temperature ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
Tensile Tests ◽  
Annealing Process ◽  
Dp Steel ◽  
Intercritical Annealing Temperature ◽  
Lower Volume

Annealing process is critical to mechanical properties and microstructure of DP steel. For DP steel with strength grade of 590MPa, experiments with different combinations of intercritical annealing temperature and over-aging temperature were carried out during annealing. The tensile tests of the final products and nanohardness tests of different phases were made, and the microstructures were analyzed. The results indicated that higher intercritical annealing temperature was favorable to higher volume fraction of martensite and lower nanohardness of martensite with lower C density. The ultimate tensile strength increased monotonously with the volume fraction of martensite increasing. Higher over aging temperature would make martensite islands be partially resolved and carbides precipitate, which made lower volume fraction of martensite, and resulted in lower nanohardness of martensite. The revealed rules could provide important guide to control material properties of DP steel by manipulating annealing process.

Crystallography and Mechanical Properties of Ultrafine TRIP-Aided Multi-Phase Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4351-4356 ◽  
Author(s):  
Masayuki Wakita ◽  
Yoshitaka Adachi ◽  
Yo Tomota
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Large Strain ◽  
High Volume ◽  
Underlying Mechanism ◽  
Carbon Steels ◽  
Diffraction Measurement ◽  
Low Carbon ◽  
Multi Phase

This study aims at examining thermomechanical controlled process to realize ultrafine TRIP-aided multi-phase microstructures in low carbon steels. Heavy deformation at a supercooled austenite region was found to lead the formation of 2 μm ferrite as well as retained austenite with high volume fraction. The morphology of retained austenite was changed from film-like shape to granular shape with lowering finish rolling temperature in austenite field. This ultrafine TRIP-aided multi-phase steel showed good balance of tensile strength with total elongation, ie. 1080MPa and 26.9%. A novel in-situ neutron diffraction measurement demonstrated that the retained granular austenite transformed to martensite at a relatively large strain compared with the retained film austenite. The therein-underlying mechanism of the good mechanical properties was discussed from the view points of the morphological and thermodynamical stabilization of retained austenite.

The Effects of Intercritical Annealing Temperature and Initial Microstructure on the Stability of Retained Austenite in a 0.1C-6Mn Steel

2016 ◽  
Vol 879 ◽  
pp. 1847-1852 ◽  
Author(s):  
Katharina Steineder ◽  
Daniel Krizan ◽  
Reinhold Schneider ◽  
Coline Beal ◽  
Christof Sommitsch
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Intercritical Annealing ◽  
Strong Dependence ◽  
Tensile Tests ◽  
Initial Microstructure ◽  
Intercritical Annealing Temperature ◽  
Batch Annealing ◽  
The Stability

The effects of the intercritical annealing temperature and initial microstructure on the stability of retained austenite were investigated for a 0.1C-6Mn (wt-%) steel. Medium-Mn transformation-induced plasticity (TRIP) steels exhibit a strong dependence of their mechanical properties on the variation of intercritical annealing temperature. This behavior is strongly linked to the amount and stability of the retained austenite. Thus, interrupted tensile tests were used to examine the effect of annealing temperature on the stabilization of the retained austenite. Detailed microstructural investigations were employed to elaborate the effects of its chemical and mechanical stabilization. Furthermore, the final microstructure was varied by applying the batch annealing step to an initial non-deformed and deformed microstructure respectively. Retained austenite stability along with resulting mechanical properties of the investigated medium-Mn TRIP steel was significantly influenced as the amount and morphology of the respective phases altered as a consequence of both initial microstructure and applied intercritical annealing temperature.

Topological Analysis of Martensite Morphology in Dual-Phase Steels

2011 ◽  
Vol 409 ◽  
pp. 725-729 ◽  
Author(s):  
Naoko Sato ◽  
Mayumi Ojima ◽  
Satoshi Morooka ◽  
Yo Tomota ◽  
Yoshitaka Adachi
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Intercritical Annealing ◽  
Topological Analysis ◽  
Three Dimensional ◽  
Dual Phase ◽  
Hardening Behavior ◽  
Dp Steels

Martensite morphology such as connectivity or dispersivity in ferrite (F)/martensite (M) dual-phase (DP) steels was investigated from topological viewpoint to reveal the effect of the martensite morphology on the mechanical properties. Topological analysis permits evaluation of the microstructural connectivity and dispersivity by measuring the number of handles, independent bodies and genus, etc. The topological analysis was performed on three-dimensional (3D) reconstructed images of the microstructure with different connectivity, dispersivity, volume fraction and hardness of martensite in DP steels that were prepared by changing the intercritical annealing temperature. The connectivity and the volume fraction of martensite increased while the dispersivity and hardness of it decreased with increasing annealing temperature. The effect of connectivity and dispersivity as well as volume fraction and hardness, in particular, on work hardening behavior was individually evaluated at a given strain.

Effect of Intercritical Annealing Temperature on Development of Cold Rolled Dual Phase Steel from Q345 Steel

2013 ◽  
Vol 313-314 ◽  
pp. 693-696
Author(s):  
Ji Yuan Liu ◽  
Fu Xian Zhu ◽  
Shi Cheng Ma
Keyword(s):  
Dual Phase Steel ◽  
Annealing Temperature ◽  
Simulation Experiment ◽  
Intercritical Annealing ◽  
Continuous Annealing ◽  
Dual Phase ◽  
Automotive Applications ◽  
Treatment Procedure ◽  
Annealing Temperatures ◽  
Cold Rolled

Cold rolled dual phase steel was developed from Q345 steel by heat treatment procedure for automotive applications. The ultimate tensile strength was improved about 100MPa higher than the traditional cold-rolled Q345 steel in the continuous annealing simulation experiment. The microstructure presented varied characteristics in different intercritical annealing temperatures; mechanical properties were changed correspondingly as well. The chief discussions are focus on the recrystallization, hardenability of austenite and martensite transformation in the experiment.

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