scholarly journals Microstructural Influence on Mechanical Properties of a Lightweight Ultrahigh Strength Fe-18Mn-10Al-0.9C-5Ni (wt%) Steel

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1305
Author(s):  
Michael Piston ◽  
Laura Bartlett ◽  
Krista R. Limmer ◽  
Daniel M. Field
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
Carbide Precipitation ◽  
Notch Toughness ◽  
Age Hardening ◽  
Austenite Matrix ◽  
Annealed Condition ◽  
Ultrahigh Strength ◽  
Hot Rolled

This study evaluates the role of thermomechanical processing and heat treatment on the microstructure and mechanical properties of a hot rolled, annealed, and aged Fe-18Mn-10Al-0.9C-5Ni (wt%) steel. The steel exhibited rapid age hardening kinetics when aged in the temperature range of 500–600 °C for up to 50 h, which has been shown in other work to be the result of B2 ordering in the ferrite and κ-carbide precipitation within the austenite matrix. The ultimate tensile strength increased from 1120 MPa in the annealed condition to 1230 MPa after 2 h of aging at 570 °C. Charpy V-notch toughness was evaluated at −40 °C in sub-sized specimens with a maximum in the annealed and quenched condition of 28.5 J in the L-T orientation.

On the Phase Transformations in Hot Rolled TRIP-Assisted Multiphase Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4333-4338
Author(s):  
Stéphane Godet ◽  
C. Georges ◽  
Pascal J. Jacques
Keyword(s):  
Mechanical Properties ◽  
Automotive Industry ◽  
Thermomechanical Processing ◽  
Simulation Techniques ◽  
Multi Stage ◽  
Composite Microstructure ◽  
Hot Rolled ◽  
Hot Rolling Conditions ◽  
Strength And Ductility ◽  
Multiphase Steels

TRIP-assisted multiphase steels exhibit an excellent balance of strength and ductility, which makes them very attractive for the automotive industry. These remarkable mechanical properties can be attributed mainly to their composite-like microstructures and to the transformation of retained austenite into martensite during straining (Transformation-Induced Plasticity). The aim of this study is to highlight the interactions between the hot rolling conditions, the transformation of austenite and formation of the microstructure, and the resulting mechanical properties. Various rolling simulation techniques were employed to determine how the composite microstructure is formed during the various steps of multi-stage thermomechanical processing.

Role of the crystallographic texture in anisotropic mechanical properties of a newly-developed hot-rolled TRIP steel

2020 ◽  
Vol 790 ◽  
pp. 139683
Author(s):  
Shih-Che Chen ◽  
Cheng-Yao Huang ◽  
Yuan-Tsung Wang ◽  
Ching-Yuan Huang ◽  
Hung-Wei Yen
Keyword(s):  
Mechanical Properties ◽  
Crystallographic Texture ◽  
Trip Steel ◽  
Anisotropic Mechanical Properties ◽  
Hot Rolled

scholarly journals Effect of As-Cast Structure and Macrosegregation on Mechanical Properties in Direct-Quenched Low-Alloy Ultrahigh-Strength Steel

2020 ◽  
Author(s):  
S. Koskenniska ◽  
A. Kaijalainen ◽  
T. Pikkarainen ◽  
S. Mehtonen ◽  
D. Porter ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Prior Austenite ◽  
Cast Structure ◽  
Ultrahigh Strength ◽  
Grain Sizes ◽  
Austenite Grain ◽  
Interdendritic Segregation ◽  
Hot Rolled ◽  
Prior Austenite Grain

Abstract The effect of as-cast structure and macrosegregation on the mechanical properties of a direct-quenched low-alloy martensitic ultrahigh-strength aluminum killed and calcium treated steel cast at different superheats was studied. Samples from the castings were laboratory hot rolled with two different finishing rolling temperatures to distinguish the effect of hot rolling. Using optical emission spectrometry, the steel composition was analyzed as a function of slab thickness in order to detect the variations in steel chemistry due to macrosegregation. Further, hardness profiles, prior austenite grain sizes and tensile and impact toughness were determined for the hot-rolled specimens. It was found that interdendritic segregation was more intense at the higher superheat, which led to more pronounced positive segregation in the columnar-to-equiaxed transition (CET) zone, and negative segregation between CET and the centerline. These macrosegregation patterns were inherited by the hot-rolled samples causing local variations in hardness, which followed the variations in carbon content. However, altering the superheat had a minor effect on the nominal transformed microstructures and nominal prior austenite grain sizes. This occurred because of the interdendritic segregation induced composition variations both enlarged and decreased by turns the grain sizes. The CET also reduced measured impact toughness values.

Formability of Twin-Roll Cast Age-Hardenable Mg-Zn Alloys

2009 ◽  
Vol 618-619 ◽  
pp. 233-237
Author(s):  
Kishore Venkatesan ◽  
Wendy Borbidge ◽  
Michael Kellam ◽  
Daniel R. East ◽  
Mark A. Gibson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Age Hardening ◽  
Traditional Practice ◽  
Sand Cast ◽  
Twin Roll Cast ◽  
Hot Rolled ◽  
Twin Roll ◽  
Cast Parts ◽  
Zn Alloys

The suitability of a twin-roll cast (TRC) age-hardenable alloy for wrought applications is explored. A Mg-4Zn (wt.%) alloy, 3mm thick, was cast using the TRC route. Deviating from the traditional practice of homogenization followed by age-hardening in die/sand cast parts, the TRC sheet, cut into small strips, was hot rolled and annealed after homogenization. They were then deep drawn and subsequently age-hardened. The rollability, mechanical properties and microstructure of the alloy at different stages of processing and after forming, are presented and discussed.

Strain-induced martensite effects on transgranular carbide precipitation in type 304 stainless steels

1991 ◽  
Vol 49 ◽  
pp. 604-605
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D. Matlock
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Deformation Twin ◽  
Austenitic Stainless Steels ◽  
Carbide Precipitation ◽  
Strain Induced Martensite ◽  
Type 304

Thermomechanically induced strain is a key variable producing accelerated carbide precipitation, sensitization and stress corrosion cracking in austenitic stainless steels (SS). Recent work has indicated that higher levels of strain (above 20%) also produce transgranular (TG) carbide precipitation and corrosion simultaneous with the grain boundary phenomenon in 316 SS. Transgranular precipitates were noted to form primarily on deformation twin-fault planes and their intersections in 316 SS.Briant has indicated that TG precipitation in 316 SS is significantly different from 304 SS due to the formation of strain-induced martensite on 304 SS, though an understanding of the role of martensite on the process has not been developed. This study is concerned with evaluating the effects of strain and strain-induced martensite on TG carbide precipitation in 304 SS. The study was performed on samples of a 0.051%C-304 SS deformed to 33% followed by heat treatment at 670°C for 1 h.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

Structural features and strength behavior of TRIP/TWIP steels

2020 ◽  
pp. 5-18
Author(s):  
D. V. Prosvirnin ◽  
◽  
M. S. Larionov ◽  
S. V. Pivovarchik ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Thermomechanical Processing ◽  
Maximum Load ◽  
Structural Features ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Structural And Functional Properties ◽  
Twip Steels ◽  
The Creation

A review of the literature data on the structural features of TRIP / TWIP steels, their relationship with mechanical properties and the relationship of strength parameters under static and cyclic loading was carried out. It is shown that the level of mechanical properties of such steels is determined by the chemical composition and processing technology (thermal and thermomechanical processing, hot and cold pressure treatment), aimed at achieving a favorable phase composition. At the atomic level, the most important factor is stacking fault energy, the level of which will be decisive in the formation of austenite twins and / or the formation of strain martensite. By selecting the chemical composition, it is possible to set the stacking fault energy corresponding to the necessary mechanical characteristics. In the case of cyclic loads, an important role is played by the strain rate and the maximum load during testing. So at high loading rates and a load approaching the yield strength under tension, the intensity of the twinning processes and the formation of martensite increases. It is shown that one of the relevant ways to further increase of the structural and functional properties of TRIP and TWIP steels is the creation of composite materials on their basis. At present, surface modification and coating, especially by ion-vacuum methods, can be considered the most promising direction for the creation of such composites.

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