scholarly journals Design and Optimization of Processing Conditions for a Recent Quenched and Partitioned Steel

2021 ◽  
Author(s):  
Eman Hassan El-Shenawy ◽  
Hoda Nasr El-Din Hedia ◽  
Mai Mohamed Kama-El-Din ◽  
Hoda Refaiy Badwy
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Testing Machine ◽  
High Strength ◽  
Processing Conditions ◽  
Critical Temperatures ◽  
Tensile Testing Machine ◽  
Heat Treated

Q&P steels as a "Third Generation" of (AHSS) exhibit excellent tensile properties, which enable producing lightweight sections for the automotive industry and at the same time keep safety requirements. This research aims to predict the proper processing conditions for developing ultra-high-strength Q&P steel with a novel chemical composition of 0.37 C-3.65 Mn- 0.65Si- 0.87 Al- 1.5 Ni- 0.05P, wt. %. To design and optimize proper heat treatment conditions, the phase diagram, CCT curve, and critical temperatures of these alloys were first implemented using THERMO-CALC and JMATE PRO software and Gleeble 3500 machine. The heat treatment process included full austenitization, then quenching at 120°C followed by partitioning at 450°C for different times. The tensile properties, microstructure, and retained austenite volume fraction of heat-treated steel was studied at room temperature by tensile testing machine, optical microscope, and XRD. The finding summarized that partitioning of this steel for 100 s during processing had developed Q&P steel with ultra-high-strength of 1104 MPa with maximum total elongation and strength elongation balance 8.1 % and 8932 MPa %, respectively. The optical micrograph showed that heat-treated specimens at different partitioning times have had a microstructure of tempered martensite, carbide free bainite, and retained austenite. Besides, the retained austenite volume fraction has decreased with increasing partitioning time, which may be due to carbide precipitation during partitioning.

scholarly journals NEW TREATMENT ROUTE FOR CLOSED-DIE FORGINGS OF STEELS WITH 2.5% MANGANESE

2018 ◽  
Vol 24 (2) ◽  
pp. 119
Author(s):  
Dagmar Bublíková ◽  
Štěpán Jeníček ◽  
Michal Peković ◽  
Hana Jirková
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Quenching Temperature ◽  
Treatment Processes ◽  
Martensitic Microstructure ◽  
Heat Treated ◽  
Forged Parts ◽  
New Treatment

<p>The requirements placed on closed-die-forged parts of advanced steels have been increasing recently. Such forgings demand an innovative approach to both design and heat treatment. It is important to obtain high strength and sufficient ductility in closed-die forgings. High strength, mostly associated with martensitic microstructure, is often to the detriment of ductility. Ductility can be improved by incorporating a certain volume fraction of retained austenite in the resulting microstructure. Among heat treatment processes capable of producing martensite and retained austenite, there is the Q&amp;P process (Quenching and Partitioning). This process is characterized by rapid cooling from the soaking temperature to the quenching temperature, which is between Ms and Mf, and subsequent reheating and holding at the partitioning temperature. Thus, strength levels of more than 2000 MPa combined with more than 10% elongation can be obtained. This experimental programme involved steels with 2.5% manganese. Forgings of these steels were heat treated using an innovative process in order to obtain an ultimate strength of more than 2000 MPa combined with sufficient elongation. Thanks to a higher manganese level, the Mf was depressed as low as 78°C, and therefore quenching was carried out not only in air but also in boiling water. Holding at the partitioning temperature of 180°C, when carbon migrates from super-saturated martensite to retained austenite, took place in a furnace. The effects of heat treatment parameters on the resulting mechanical properties and microstructure evolution in various locations of the forging were studied.</p>

Microstructure and Tensile Properties of TRIP-Aided Steel Sheet Subjected to Hot-Rolling and Austempering

2021 ◽  
Vol 1016 ◽  
pp. 732-737
Author(s):  
Junya Kobayashi ◽  
Hiroto Sawayama ◽  
Naoya Kakefuda ◽  
Goroh Itoh ◽  
Shigeru Kuraoto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hot Rolling ◽  
Manufacturing Process ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
High Strength ◽  
Isothermal Transformation ◽  
Transformation Process ◽  
Steel Sheets

Various high strength steel sheets for weight reduction and safety improvement of vehicles have been developed. TRIP-aided steel with transformation induced plasticity of the retained austenite has high strength and ductility. Conventional TRIP-aided steels are subjected to austempering process after austenitizing. Generally, elongation and formability of TRIP-aided steel are improved by finely dispersed retained austenite in BCC phase matrix. The finely dispersed retained austenite and grain refinement of TRIP-aided steel can be achieved by hot rolling with heat treatment. Therefore, the improvement of mechanical properties of TRIP-aided steel is expected from the manufacturing process with hot rolling and then isothermal transformation process. In this study, thermomechanical heat treatment is performed by combining hot rolling and isothermal holding as the manufacturing process of TRIP-aided steel sheets. The complex phase matrix is obtained by hot rolling and then isothermal holding. Although the hardness of the hot rolled and isothermal held TRIP-aided steel is decreased, the volume fraction of retained austenite is increased.

Effects of Heat Treatment on Microstructure of High-Strength Manganese-Silicon Steels

2017 ◽  
Vol 270 ◽  
pp. 239-245
Author(s):  
Dagmar Bublíková ◽  
Štěpán Jeníček ◽  
Kateřina Opatová ◽  
Bohuslav Mašek
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Microstructure Evolution ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Quenching And Partitioning ◽  
Alloying Additions ◽  
New Procedures ◽  
Strength And Ductility

Today’s advanced steels are required to possess high strength and ductility. This can be accomplished by producing appropriate microstructures with a certain volume fraction of retained austenite. The resulting microstructure depends on material’s heat treatment and alloying. High ultimate strengths and sufficient elongation levels can be obtained by various methods, including quenching and partitioning (Q&P process). The present paper introduces new procedures aimed at simplifying this process with the use of material-technological modelling. Three experimental steels have been made and cast for this investigation, whose main alloying additions were manganese, silicon, chromium, molybdenum and nickel. The purpose of manganese addition was to depress the Ms and Mf temperatures. The Q&P process was carried out in a thermomechanical simulator for better and easier control. The heat treatment parameters were varied between the sequences and their effect on microstructure evolution was evaluated. They included the cooling rate, partitioning temperature and time at partitioning temperature. Microstructures including martensite with strength levels of more than 2000 MPa and elongation of 10–15 % were obtained.

scholarly journals Determination of Hardness and Tensile Properties of Dissimilar Phase Structured Steel Weld

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
I M Momoh ◽  
O A Adeyemi ◽  
O M Oluwafemi ◽  
O D Ogundare ◽  
S I Salawu
Keyword(s):  
Tensile Properties ◽  
Oil And Gas ◽  
Testing Machine ◽  
Oil And Gas Industry ◽  
Tensile Testing Machine ◽  
Gas Industry ◽  
Heat Treated ◽  
Hardness Property ◽  
Submerged Arc

This work involves the use of submerged arc welding (SAW) technique in joining heat treated steel in alternate arrangement. The selected as-received steel was initially cut, machined and heat treated to develop a conventional microstructure prior to joining operation. All samples were subsequently characterized to investigate the effect of the process on the mechanical behaviors. 3360 Instron Universal Tensile testing machine was used for the tensile properties evaluation; Vickers’ microhardness testing machine was also used for the hardness evaluation at various zones. From the result, it was found that interchanging arrangement of the microstructures during welding yield better combined properties of the ultimate tensile strength, yield strength and with improvement in the strain-to-fracture of some of the samples. The adopted mechanism was also observed to yield better hardness property on the sample. This led to the recommendation of this technique to the oil and gas industry that need to transport their products via the giant water bodies to clients.

scholarly journals High Versatility of Niobium Alloyed AHSS

2017 ◽  
Vol 62 (3) ◽  
pp. 1485-1491 ◽  
Author(s):  
L. Kučerová ◽  
K. Opatová ◽  
J. Káňa ◽  
H. Jirková
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Processing Parameters ◽  
High Ductility ◽  
Processing Strategies ◽  
Cooling Schedules ◽  
Final Microstructure ◽  
Steel Processing

AbstractThe effect of processing parameters on the final microstructure and properties of advanced high strength CMnSiNb steel was investigated. Several processing strategies with various numbers of deformation steps and various cooling schedules were carried out, namely heat treatment without deformation, conventional quenching and TRIP steel processing with bainitic hold or continuous cooling. Obtained multiphase microstructures consisted of the mixture of ferrite, bainite, retained austenite and M-A constituent. They possessed ultimate tensile strength in the range of 780-970 MPa with high ductility A5mmabove 30%. Volume fraction of retained austenite was for all the samples around 13%. The only exception was reference quenched sample with the highest strength 1186 MPa, lowest ductility A5mm= 20% and only 4% of retained austenite.

Effects of Heat Treatment on Unique Layered Microstructure and Tensile Properties of TiAl Fabricated by Electron Beam Melting

2018 ◽  
Vol 941 ◽  
pp. 1366-1371
Author(s):  
Masahiro Sakata ◽  
Jong Yeong Oh ◽  
Ken Cho ◽  
Hiroyuki Y. Yasuda ◽  
Mitsuharu Todai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electron Beam ◽  
Tensile Properties ◽  
Heat Treatment Temperature ◽  
Electron Beam Melting ◽  
Room Temperature ◽  
High Strength ◽  
Treatment Temperature ◽  
Heat Treated ◽  
High Elongation

In the present study, effects of heat treatment on microstructures and tensile properties of the cylindrical bars of Ti-48Al-2Cr-2Nb (at.%) alloy with unique layered microstructure consisting of equiaxed γ grains region (γ band) and duplex-like region fabricated by electron beam melting (EBM) were investigated. We found that it is possible to control width of the γ bands (Wγ) by heat treatments at 1100°C and 1190°C. The Wγ increases with decreasing heat treatment temperature. The bars heat-treated at 1190°C exhibit high elongation of 2.9% at room temperature (RT) with maintaining high strength. The RT elongation increases with increasing the Wγ because of increasing deformable regions. In contrast, the RT elongation of the bars decreases with increasing the Wγ when Wγ is very large. This is because the large γ band leads intergranular fracture. These results indicate that there is appropriate width for the γ band to obtain excellent tensile properties at RT.

scholarly journals EFFECTS OF THE HEAT TREATMENT ON THE MECHANICAL PROPERTIES OF 6201 ALUMINIUM ALLOY WIRE

2019 ◽  
Vol 57 (3A) ◽  
pp. 11 ◽  
Author(s):  
Khanh Cong Huynh
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminium Alloy ◽  
Tensile Testing ◽  
Solution Heat Treatment ◽  
Testing Machine ◽  
Machine Model ◽  
Tensile Testing Machine ◽  
Alloy Wire ◽  
Heat Treated

Type 6201 aluminium alloy wires are produced by drawing 4.7 mm diameter billet-on-billet extruded redraw rod down to 2.7 mm diameter wires. Before drawing, the first group of redraw rod coils was annealed at 480oC for 4 hours to reduce the hardness of the redraw rod. The second group of redraw rod coils was drawn without annealing. With each group of redraw rod, after drawing, some wire coils were solution heat treated, then artificially aged or naturally aged. The other wire coils were artificially aged or naturally aged without solution heat treatment. Mechanical properties of the wires were assessed by a tensile testing machine (model UTM-1000)With suitable aging temperature and aging time, wires produced from each group of redraw rod coils with or without solution heat treatment attain tensile requirements of ASTM B398, but wires produced with solution heat treatment attain higher elongation than wires produced without solution heat treatment.

Two-Step Quenching & Partitioning of 42SiCrB Steel

2014 ◽  
Vol 783-786 ◽  
pp. 738-743 ◽  
Author(s):  
Niko Grosse-Heilmann ◽  
Isabella Maria Zylla ◽  
Ernst Kozeschnik ◽  
Andreas Peters
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Thermal Process ◽  
Treatment Process ◽  
Volume Fraction ◽  
High Strength ◽  
Carbon Diffusion ◽  
Process Route ◽  
Low Alloyed Steel ◽  
Step Quenching

In recent years, Quenching and Partitioning (Q&P) became an interesting thermal process route for semi-finished high strength low alloyed steel components. Recent publications demonstrate promising mechanical properties with considerable ductility enhancement. To assess the potential of the two-step Q&P heat treatment in seamless tube production, corresponding tests are carried out on 42SiCrB steel (0.42wt% C, 2.0wt% Si, 1.3wt.% Cr, 0.6wt.% Mn, 0.002wt.% B). Feasible Q&P heat treatment process parameters are identified using the Constrained-Carbon-Equilibrium (CCE) model, carbon diffusion calculations and isothermal TTT curves with previous quenching. Furthermore achieved volume fraction of retained austenite is analyzed by XRD experiments.

scholarly journals EFFECTS OF COOLING RATE ON THE VOLUME FRACTION OF RETAINED AUSTENITE IN FORGINGS FROM HIGH-STRENGTH Mn-Si STEELS

2019 ◽  
Vol 25 (2) ◽  
pp. 93 ◽  
Author(s):  
Dagmar Bublíková ◽  
Hana Jirková ◽  
Kateřina Rubešová ◽  
Michal Peković ◽  
Julie Volkmannová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Retained Austenite ◽  
Physical Simulation ◽  
Volume Fraction ◽  
High Strength ◽  
Hot Water ◽  
Quenching Temperature ◽  
Soaking Temperature

<p class="AMSmaintext"><span lang="EN-GB">Various ways are sought today to increase mechanical properties of steels while maintaining their good strength and ductility. Besides effective alloying strategies, one method involves preserving a certain amount of retained austenite in a martensitic matrix. The steel which was chosen as an experimental material for this investigation contained 2.5% manganese, 2.09% silicon and 1.34% chromium, with additions of nickel and molybdenum. An actual closed-die forged part was made of this steel. This forged part was fitted with thermocouples attached to its surface and placed in its interior and then treated using the Q&amp;P process. Q&amp;P process is characterized by rapid cooling from a soaking temperature to a quenching temperature, which is between the Ms and the Mf, and subsequent reheating to and holding at a partitioning temperature where retained austenite becomes stable. The quenchant was hot water. Cooling took place in a furnace. Heat treatment profiles were constructed from the thermocouple data and the process was then replicated in a thermomechanical simulator. The specimens obtained in this manner were examined using metallographic techniques. The effects of cooling rate on mechanical properties and the amount of retained austenite were assessed. The resultant ultimate strength was around 2100 MPa. Elongation and the amount of retained austenite were 15% and 17%, respectively. Microstructures and mechanical properties of the specimens were then compared to the real-world forged part in order to establish whether physical simulation could be employed for laboratory-based optimization of heat treatment of forgings.</span></p>

Vanadium Additions to a High-Cr White Iron and its Effects on the Abrasive Wear Behavior.

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3077-3089
Author(s):  
Alexeis Sánchez ◽  
Arnoldo Bedolla-Jacuinde ◽  
Francisco V. Guerra ◽  
I. Mejía
Keyword(s):  
Heat Treatment ◽  
Abrasive Wear ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Wear Behaviour ◽  
White Iron ◽  
Heat Treated ◽  
Bulk Hardness ◽  
Abrasive Wear Behavior ◽  
Vanadium Carbides

AbstractFrom the present study, vanadium additions up to 6.4% were added to a 14%Cr-3%C white iron, and the effect on the microstructure, hardness and abrasive wear were analysed. The experimental irons were melted in an open induction furnace and cast into sand moulds to obtain bars of 18, 25, and 37 mm thickness. The alloys were characterized by optical and electronic microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900°C for 45 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under a load of 60 N for 1500 m. The results show that, vanadium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming primary vanadium carbides; thus, decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 20% for the iron with 6.4%V;but overall CVF content (M7C3 + VC) is constant at 30%. Wear behaviour was better for the heat-treated alloys and mainly for the 6.4%V iron. Such a behaviour is discussed in terms of the CVF, the amount of vanadium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

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