scholarly journals Effect of Manganese on the Structure-Properties Relationship of Cold Rolled AHSS Treated by a Quenching and Partitioning Process

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1122 ◽  
Author(s):  
Simone Kaar ◽  
Daniel Krizan ◽  
Reinhold Schneider ◽  
Coline Béal ◽  
Christof Sommitsch
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Total Elongation ◽  
Process Window ◽  
Quenching And Partitioning ◽  
Strain Behavior ◽  
Strain Induced Martensite ◽  
Steel Grades ◽  
Mn Content

The present work focuses on the investigation of both microstructure and resulting mechanical properties of different lean medium Mn Quenching and Partitioning (Q&P) steels with 0.2 wt.% C, 1.5 wt.% Si, and 3–4 wt.% Mn. By means of dilatometry, a significant influence of the Mn-content on their transformation behavior was observed. Light optical and scanning electron microscopy (LOM, SEM) was used to characterize the microstructure consisting of tempered martensite (α’’), retained austenite (RA), partially bainitic ferrite (αB), and final martensite (α’final) formed during final cooling to room temperature (RT). Using the saturation magnetization measurements (SMM), a beneficial impact of the increasing Mn-content on the volume fraction of RA could be found. This remarkably determined the mechanical properties of the investigated steels, since the larger amount of RA with its lower chemical stabilization against the strain-induced martensite transformation (SIMT) highly influenced their overall stress-strain behavior. With increasing Mn-content the ultimate tensile strength (UTS) rose without considerable deterioration in total elongation (TE), leading to an enhanced combination of strength and ductility with UTS × TE exceeding 22,500 MPa%. However, for the steel grades containing an elevated Mn-content, a narrower process window was observed due to the tendency to form α’final.

scholarly journals Effect of Pre-Quenching Process on Microstructure and Mechanical Properties in a Nb-Microalloyed Low Carbon Q-P Steel

2015 ◽  
Vol 816 ◽  
pp. 729-735 ◽  
Author(s):  
Jun Zhang ◽  
Hua Ding ◽  
Jing Wei Zhao
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Room Temperature ◽  
Volume Fraction ◽  
Total Elongation ◽  
Trip Effect ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
The Stability ◽  
Critical Annealing

A refined microstructure consisting of martensite and retained austenite at room temperature has been produced in a Nb-microalloyed low carbon Si-Mn steel by a novel heat-treatment, pre-quenching prior to quenching and partitioning processes (Q&Q-P). The results showed that compared with the conventional quenching and partitioning steel the mechanical properties of steel obtained by the novel treatment have been significantly improved, with a good combination of ultimate tensile strength (1000MPa) and total elongation (above 30%). Meanwhile, the volume fraction of retained austenite has been increased. It was found that the improvement of mechanical properties was mainly attributed to the enhanced TRIP effect due to the relatively high fraction of metastable retained austenite at room temperature. The increased stability of austenite results from the C and Mn partitioning during inter-critical annealing, which increased the chemical stability of austenite. The formation of refined austenite at inter-critical annealing also had a positive effect on the stability of the austenite. As a consequence, the volume fraction of retained austenite at room temperature was significantly increased. Compared with the Q-P steel, the Q&Q-P steel exhibited higher work hardening exponents during the stage of TRIP effect and had the higher ductility.

scholarly journals The Effect of Quenching and Partitioning (Q&P) Heat Treatment on the Microstructure and Mechanical Properties of High Boron Steel

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1556
Author(s):  
Zhao Li ◽  
Run Wu ◽  
Mingwei Li ◽  
Song-Sheng Zeng ◽  
Yu Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Volume Fraction ◽  
Martensitic Steel ◽  
Boron Steel ◽  
Quenching And Partitioning ◽  
Effect Mechanism ◽  
Microstructure And Mechanical Properties ◽  
High Boron ◽  
Cast Condition

High boron steel is prone to brittle failure due to the boride distributed in it with net-like or fishbone morphology, which limit its applications. The Quenching and Partitioning (Q&P) heat treatment is a promising process to produce martensitic steel with excellent mechanical properties, especially high toughness by increasing the volume fraction of retained austensite (RA) in the martensitic matrix. In this work, the Q&P heat treatment is used to improve the inherent defect of insufficient toughness of high boron steel, and the effect mechanism of this process on microstructure transformation and the change of mechanical properties of the steel has also been investigated. The high boron steel as-casted is composed of martensite, retained austensite (RA) and eutectic borides. A proper quenching and partitioning heat treatment leads to a significant change of the microstructure and mechanical properties of the steel. The net-like and fishbone-like boride is partially broken and spheroidized. The volume fraction of RA increases from 10% in the as-cast condition to 19%, and its morphology also changes from blocky to film-like. Although the macro-hardness has slightly reduced, the toughness is significantly increased up to 7.5 J·cm−2, and the wear resistance is also improved.

Microstructure and Mechanical Properties of a Low-Carbon Steel Treated by One-Step Quenching and Partitioning Process

2014 ◽  
Vol 1082 ◽  
pp. 202-207 ◽  
Author(s):  
Shu Yan ◽  
Xiang Hua Liu
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Microstructural Evolution ◽  
Retained Austenite ◽  
Uniform Elongation ◽  
Low Carbon Steel ◽  
Total Elongation ◽  
Low Carbon ◽  
Quenching And Partitioning ◽  
Partitioning Time

A low carbon steel was treated by quenching and partitioning (Q&P) process, and a detailed characterization of the microstructural evolution and testing of mechanical properties were carried out. The resulted mechanical properties indicate that with the partitioning time increasing, the tensile strength decreases rapidly first and then remains stable, and the total elongation increases first then decreases. The investigated steel subjected to Q&P process exhibits excellent products of strength and elongation (17.8-20.6 GPa•%). The microstructural evolution of martensite matrix during the partitioning step was observed, and the morphology and content of retained austenite were characterized. The working hardening behavior of the samples was analyzed, and the retained austenite with higher carbon content contributes to the uniform elongation more effectively.

Isothermal Transformation, Microstructure and Mechanical Properties of Ausformed Low-Carbon Carbide-Free Bainitic Steel

2018 ◽  
Vol 941 ◽  
pp. 329-333 ◽  
Author(s):  
Jiang Ying Meng ◽  
Lei Jie Zhao ◽  
Fan Huang ◽  
Fu Cheng Zhang ◽  
Li He Qian
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Isothermal Transformation ◽  
Bainitic Transformation ◽  
Isothermal Treatment ◽  
Bainitic Steel ◽  
Low Carbon ◽  
Microstructure And Mechanical Properties

In the present study, the effects of ausforming on the bainitic transformation, microstructure and mechanical properties of a low-carbon rich-silicon carbide-free bainitic steel have been investigated. Results show that prior ausforming shortens both the incubation period and finishing time of bainitic transformation during isothermal treatment at a temperature slightly above the Mspoint. The thicknesses of bainitic ferrite laths are reduced appreciably by ausforming; however, ausforming increases the amount of large blocks of retained austenite/martenisite and decreases the volume fraction of retained austenite. And accordingly, ausforming gives rise to significant increases in both yield and tensile strengths, but causes noticeable decreases in ductility and impact toughness.

scholarly journals Microstructure and Mechanical Properties of Tempered Ausrolled Nanobainite Steel

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 573
Author(s):  
Jing Zhao ◽  
Dezheng Liu ◽  
Yan Li ◽  
Yongsheng Yang ◽  
Tiansheng Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Energy Yield ◽  
Partial Recovery ◽  
Fracture Appearance ◽  
The Impact

The microstructures and mechanical properties of ausrolled nanobainite steel, after being tempered at temperatures in the range of 200−400 °C, were investigated in this study. After being tempered, bainitic ferrite is coarsened and the volume fraction of retained austenite is reduced. The hardness and ultimate tensile strength decrease sharply. The impact energy, yield strength, and elongation increase with elevated tempered temperature at 200–300 °C but decrease with elevated tempered temperature when the samples are tempered at 350 °C and 400 °C. The fracture appearance of all the samples after impact tests is a brittle fracture. The variation of the mechanical properties may be due to partial recovery and recrystallization.

Effects of Quenching and Partitioning Process on Mechanical Properties of a Hot-Stamping Steel

2014 ◽  
Vol 788 ◽  
pp. 340-345 ◽  
Author(s):  
Ming Cheng ◽  
Hong Wu Song ◽  
Xin Li ◽  
Shi Hong Zhang ◽  
Ming Cheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Treatment Process ◽  
Volume Fraction ◽  
Hot Stamping ◽  
Quenching Temperature ◽  
Quenching And Partitioning ◽  
22Mnb5 Steel ◽  
Partitioning Time ◽  
Hot Stamping Steel ◽  
Quenching And Partitioning Process

As a novel heat treatment process, Q&P (quenching and partitioning) process can be applied to enhance the ductility of steels. In this paper, the effects of different parameters of Q&P process (such as quenching temperature, partitioning temperature and partitioning time) on mechanical properties and microstructure of 22MnB5 steel was investigated. Analysis demonstrated that austenite can be stabilized via Q&P process and the volume fraction of retained austenite increases with the partitioning temperature and the partitioning time. The mechanical properties of the steel can be controlled to acquire the steel with excellent strength-ductility balance by Q&P process.

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.

Mechanical properties and mechanical behavior of (SiO2)f/SiO2 composites with 3D six-directional braided quartz fiber preform

2012 ◽  
Vol 19 (2) ◽  
pp. 113-117 ◽  
Author(s):  
Yong Liu ◽  
Zhaofeng Chen ◽  
Jianxun Zhu ◽  
Yun Jiang ◽  
Binbin Li
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Thermal Structure ◽  
Three Dimensional ◽  
Shear Loading ◽  
Failure Behavior ◽  
Fiber Volume ◽  
Strain Behavior ◽  
Highly Nonlinear ◽  
Nonlinear Stress

Abstract(SiO2)f/SiO2 composites reinforced with three-dimensional (3D) six-directional preform were fabricated by the silicasol-infiltration-sintering method. The nominal fiber volume fraction was 47%. To characterize the mechanical properties of the composites, mechanical testing was carried out under various loading conditions, including tensile, flexural, and shear loading. The composite exhibited highly nonlinear stress-strain behavior under all the three types of loading. The results indicated that the 3D six-directional braided (SiO2)f/SiO2 composites exhibited superior flexural properties and good shear resistant as compared with other types of preform (2.5D and 3D four-directional)-reinforced (SiO2)f/SiO2 composites. 3D six-directional braided (SiO2)f/SiO2 composite exhibited graceful failure behavior under loading. The addition of 5th and 6th yarns resulted in controlled fracture and hence these 3D six-directional braided composites could possibly be suitable for thermal structure components.

scholarly journals Nodule count effect on microstructure and mechanical properties of hypo-eutectic ADI alloyed with nickel

2021 ◽  
Vol 57 (1) ◽  
pp. 115-124
Author(s):  
E. Colin-García ◽  
A. Cruz-Ramírez ◽  
J.A. Romero-Serrano ◽  
R.G. Sánchez-Alvarado ◽  
V.H. Gutiérrez-Pérez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Brinell Hardness ◽  
Process Window ◽  
High Carbon ◽  
Sand Cast ◽  
Nodule Count ◽  
Austempering Temperature ◽  
Different Thickness ◽  
Good Agreement

Samples of ductile iron alloyed with 0.88 % Ni with a nodule count of 606, 523, and 290 nod/mm2 were obtained from sand cast plates of different thickness in the range from 8.46 to 25.4 mm. The effect of the nodule count was evaluated during the austempering process held at 285?C and austempering times of 15, 30, 45, 60, 70, and 90 min. The volume fraction of high carbon austenite increased when the nodule count increased, however, the carbon content of the high carbon austenite kept almost constant. The process window was narrow, requiring a lower austempering time when the nodule count increased. The combination of a higher nodule count and low austempering temperature allowed obtaining a fine ausferritic microstructure which led to higher Brinell hardness and tensile strength. The process window was determined by XRD measurements and it was in good agreement with the microstructural and hardness evolution as the austempering time increased.

scholarly journals Performance of Mechanical Properties of Ultrahigh-Strength Ferrous Steels Related to Strain-Induced Transformation

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 875 ◽  
Author(s):  
Koh-ichi Sugimoto
Keyword(s):  
Mechanical Properties ◽  
Martensite Transformation ◽  
Retained Austenite ◽  
Quenching And Partitioning ◽  
Transformation Induced Plasticity ◽  
Ultrahigh Strength ◽  
Bainitic Steels ◽  
Strain Induced Martensite ◽  
Industry Sectors ◽  
Manganese Steels

Ultrahigh-strength ferrous steels, related to the strain-induced martensite transformation (or transformation-induced plasticity: TRIP) of metastable retained austenite, such as TRIP-aided bainite/martensite steels, quenching and partitioning steels, nanostructured bainitic steels (or carbide free bainitic steels) and medium manganese steels, are currently receiving a great deal of attention from both academic and industry sectors, due to their excellent formability and mechanical properties [...]

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