Ultrafine Grained High Strength Low Alloy Steel with High Strength and High Ductility

2010 ◽  
Vol 654-656 ◽  
pp. 238-241 ◽  
Author(s):  
Jie Shi ◽  
Wen Quan Cao ◽  
Han Dong
Keyword(s):  
Electron Microscopy ◽  
Alloy Steel ◽  
Volume Fraction ◽  
High Strength ◽  
Uniaxial Tensile ◽  
X Rays ◽  
High Ductility ◽  
Low Alloy Steel ◽  
Uniaxial Tensile Testing ◽  
Ultrafine Grained

In this study a C-Mn High Strength Low Alloy steel (HSLAs) was processed by quenching and austenite reverted transformation during annealing (ART-annealing), which results in an ultrafine grained duplex microstructure characterized by scanning electron microscopy equipped with electron back scattered diffraction, transmission electron microscopy and x-rays diffraction (SEM/EBSD, TEM and XRD). Microstructural observation revealed that the full hard martensitic microstucture gradually transformed into ultrafine grained duplex structure with austenite volume fraction up to 30% at specific annealing conditions. Mechanical properties of this processed steel measured by uniaxial tensile testing demonstrated that an excellent combination of strength (Rm~1GPa) and total elongation (A5~40%) at 30% metastable austenite condition in studied C-Mn-HSLAs. This substantially improved strength and ductility were attributed to the strain induced phase transformation of retained austenite dispersed throughout the ultrafine grained microstructure. At last it is proposed that ART-annealing is a promising way to produce high strength and high ductility steel products.

scholarly journals Reduction of Residual Stress for High-Strength Low-Alloy Steel Strip Based on Finite Element Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Zengshuai Qiu ◽  
Anrui He ◽  
Jian Shao ◽  
Xiaoming Xia
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Boundary Conditions ◽  
Alloy Steel ◽  
Steel Strip ◽  
High Strength ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Fe Model ◽  
Low Alloy Steel

Intensive cooling technology is widely utilized in the production of high-strength hot-rolled steel strip. However, intensive cooling at high cooling rate may cause stress heterogeneity on a steel strip, which further generates great residual stress and influences steel strip shape. In this study, a three-dimensional finite element (FE) model of high-strength low-alloy steel strip on the run-out table coupled with heat transfer, phase transformation, and strain/stress is developed by ABAQUS software. To enhance modeling precision, several experiments are conducted, such as uniaxial tensile test at multiple temperatures, dynamic continuous cooling transformation, and scanning electron microscopy, to determine the material properties and boundary conditions of the FE model. Four new models are established based on this model to reduce the residual stress of strip by modifying the initial and boundary conditions. Results show that reducing the initial transverse temperature difference is the most effective in reducing residual stress, followed by sparse cooling, edge masking, and posterior cooling.

Application of Quenching and Partitioning to Improve Ductility of Ultrahigh Strength Low Alloy Steel

2010 ◽  
Vol 654-656 ◽  
pp. 29-32 ◽  
Author(s):  
Wen Quan Cao ◽  
Cun Yu Wang ◽  
Jie Shi ◽  
Han Dong
Keyword(s):  
Alloy Steel ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Tensile Elongation ◽  
High Strength ◽  
Total Elongation ◽  
Low Alloy Steel ◽  
Quenching And Partitioning ◽  
Multiphase Microstructure ◽  
Ultrahigh Strength

In this study Quenching and Partitioning (Q&P) as proposed by Speer was applied to improve the ductility of C-Mn high strength Low Alloy steel (HSLAs). Microstructural observations revealed a multiphase microstructure including first martensite, fresh martensite and retained austenite in the Q&P processed steel. During tensile process, the austenite volume fraction gradually decreased with strain increasing, suggesting the phase transformation induced plasticity for the Q&P processed steel. Ultrahigh strength about 1300-1800MPa and tensile elongation about 20% were obtained after Q&P processing at specific conditions, which is significant higher than that of ~10% of conventional martensitic steel. The the product of tensile strength to total elongation increased from 25 to 35GPa% with increasing carbon content in studied steel. This improved mechanical properties were related to the ductility contribution from TRIP effects of the retained austenite and strength contribution from the hard martensitic matrix. At last it was turned out that the Q&P process is a promising way to produce ultrahigh strength steel with relative high ductility under tailored heat treatment conditions for different micro-alloyed carbon steel.

scholarly journals Detection and Estimation of Retained Austenite in a High Strength Si-Bearing Bainite-Martensite-Retained Austenite Micro-Composite Steel after Quenching and Bainitic Holding (Q&B)

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 492 ◽  
Author(s):  
Shima Pashangeh ◽  
Hamid Reza Karimi Zarchi ◽  
Seyyed Sadegh Ghasemi Banadkouki ◽  
Mahesh C. Somani
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Isothermal Treatment ◽  
X Rays ◽  
Vibrating Sample Magnetometry ◽  
Volume Fractions

To develop an advanced high strength steel with reasonable ductility based on low alloying concept as well as micro-composite microstructure essentially consisting of bainite, martensite and retained austenite, a Si-bearing, low alloy medium carbon sheet steel (DIN1.5025 grade) was subjected to typical quenching and bainitic holding (Q&B) type isothermal treatment in the bainitic region close to martensite start temperature (Ms) for different durations in the range 5s to 1h. While the low temperature bainite has the potential to provide the required high strength, a small fraction of finely divided austenite stabilized between the bainitic laths is expected to provide the desired elongation and improved work hardening. Various materials characterization techniques including conventional light metallography, field emission scanning electron microscopy FE-SEM, electron backscatter diffraction (EBSD), differential thermal analysis, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM), were used to detect and estimate the volume fraction, size and morphology and distribution of retained austenite in the micro-composite samples. The results showed that the color light metallography technique using LePera’s etching reagent could clearly reveal the retained austenite in the microstructures of the samples isothermally held for shorter than 30s, beyond which an unambiguous distinction between the retained austenite and martensite was imprecise. On the contrary, the electron microscopy using a FE-SEM was not capable of identifying clearly the retained austenite from bainite and martensite. However, the EBSD images could successfully distinguish between bainite, martensite and retained austenite microphases with good contrast. Although the volume fractions of retained austenite measured by EBSD are in accord with those obtained by XRD and color light metallography, the XRD measurements showed somewhat higher fractions owing to its ability to acquisition and analyze the diffracted X-rays from very finely divided retained austenite, too. The differential thermal analysis and vibrating sample magnetometry techniques also confirmed the stabilization of retained austenite finely divided in bainite/martensite micro-composite microstructures. In addition, the peak temperatures and intensities corresponding to the decomposition of retained austenite were correlated with the related volume fractions and carbon contents measured by the XRD analysis.

TENFORM XF450

Alloy Digest ◽  
2007 ◽  
Vol 56 (1) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Alloy Steel ◽  
High Strength ◽  
Bend Strength ◽  
Low Alloy Steel ◽  
Hot Rolled

Abstract The high strength of Tenform XF450, a hot-rolled high-strength low-alloy steel, allows the user to increase the strength of a finished component or to reduce the thickness. The steel is used in the construction and the automotive industries. This datasheet provides information on composition, physical properties, tensile properties. and bend strength. It also includes information on forming. Filing Code: CS-148. Producer or source: Hille & Mueller, USA Inc. See also Alloy Digest CS-173, November 2012.

Characterization of Clad Joints of High Strength Low Alloy Steel with Stainless Steel and Titanium

2018 ◽  
Vol 51 (4) ◽  
pp. 46
Author(s):  
N. Venkateswara Rao ◽  
G. Madhusudhan Reddy ◽  
S. Nagarjuna
Keyword(s):  
Stainless Steel ◽  
Alloy Steel ◽  
High Strength ◽  
Low Alloy Steel

New insight into the hardenability of high strength low alloy steel from the perspective of crystallography

2021 ◽  
Vol 292 ◽  
pp. 129624
Author(s):  
Y.S. Yu ◽  
Z.Q. Wang ◽  
B.B. Wu ◽  
X.Q. Rong ◽  
L.J. Wei ◽  
...  
Keyword(s):  
Alloy Steel ◽  
High Strength ◽  
Low Alloy Steel ◽  
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