scholarly journals Microstructure and Mechanical Properties of Cast and Hot-Rolled Medium-Carbon Steels under Isothermal Heat-Treatment Conditions

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1950
Author(s):  
Byungsue Shin ◽  
Kwangyuk Kim ◽  
Sung Yi ◽  
Sanggyu Choi ◽  
Soongkeun Hyun
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Steel ◽  
Bainitic Ferrite ◽  
Medium Carbon Steel ◽  
Treatment Temperature ◽  
Isothermal Heat Treatment ◽  
Medium Carbon ◽  
Treatment Conditions ◽  
Hot Rolled

In this study, the changes in the microstructure and mechanical properties during isothermal heat treatment of cast steel before and after hot deformation were investigated using medium-carbon steel with low alloy content. The microstructural characteristics of the cast and hot-rolled medium-carbon steel under isothermal heat-treatment conditions were examined using optical microscopy and scanning electron microscopy in conjunction with electron backscatter diffraction. The variation in the mechanical properties was evaluated using Rockwell hardness and tensile tests. After maintaining an austenitizing condition at 1200 °C for 30 min, an isothermal heat treatment was performed in the range 350–500 °C, followed by rapid cooling with water. Both the cast steel and hot-rolled steel did not completely transform into bainitic ferrite during isothermal heat treatment. The partially untransformed microstructure was a mixture of martensite and acicular ferrite. At 500 °C, the prior austenite phase changed to Widmanstätten ferrite and pearlite. At 450 °C, bainitic ferrite and cementite were coarsened by the coalescence of ferrite and subsequent diffusive growth. The mechanical properties increased as the isothermal heat-treatment temperature decreased, and the hardness of the cast steel was generally higher than that of the hot-rolled steel. Hardness and strength showed similar trends, and overall mechanical properties tend to decrease as the isothermal heat-treatment temperature increases, but there are slight differences depending on complex factors such as various phase fractions and grain size.

INFLUENCE THE QUENCHING AND TEMPERING ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND SURFACE ROUGHNESS, OF MEDIUM CARBON STEEL

2018 ◽  
Vol 18 (1) ◽  
pp. 125-135
Author(s):  
Sattar H A Alfatlawi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Surface Roughness ◽  
Carbon Steel ◽  
Cold Water ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Heating And Cooling ◽  
Treatment Processes ◽  
Quenching And Tempering

One of ways to improve properties of materials without changing the product shape toobtain the desired engineering applications is heating and cooling under effect of controlledsequence of heat treatment. The main aim of this study was to investigate the effect ofheating and cooling on the surface roughness, microstructure and some selected propertiessuch as the hardness and impact strength of Medium Carbon Steel which treated at differenttypes of heat treatment processes. Heat treatment achieved in this work was respectively,heating, quenching and tempering. The specimens were heated to 850°C and left for 45minutes inside the furnace as a holding time at that temperature, then quenching process wasperformed in four types of quenching media (still air, cold water (2°C), oil and polymersolution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°Cwith one hour as a soaking time for each temperature, then were all cooled by still air. Whenthe heat treatment process was completed, the surface roughness, hardness, impact strengthand microstructure tests were performed. The results showed a change and clearimprovement of surface roughness, mechanical properties and microstructure afterquenching was achieved, as well as the change that took place due to the increasingtoughness and ductility by reducing of brittleness of samples.

scholarly journals Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 778 ◽  
Author(s):  
Omid Hajizad ◽  
Ankit Kumar ◽  
Zili Li ◽  
Roumen H. Petrov ◽  
Jilt Sietsma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Behavior ◽  
Mechanical Performance ◽  
Electron Backscatter Diffraction ◽  
Bainitic Ferrite ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Uniaxial Tensile ◽  
Isothermal Heat Treatment

Wheel–rail contact creates high stresses in both rails and wheels, which can lead to different damage, such as plastic deformation, wear and rolling contact fatigue (RCF). It is important to use high-quality steels that are resistant to these damages. Mechanical properties and failure of steels are determined by various microstructural features, such as grain size, phase fraction, as well as spatial distribution and morphology of these phases in the microstructure. To quantify the mechanical behavior of bainitic rail steels, uniaxial tensile experiments and hardness measurements were performed. In order to characterize the influence of microstructure on the mechanical behavior, various microscopy techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), were used. Three bainitic grades industrially known as B360, B1400 plus and Cr-Bainitic together with commonly used R350HT pearlitic grade were studied. Influence of isothermal bainitic heat treatment on the microstructure and mechanical properties of the bainitic grades was investigated and compared with B360, B1400 plus, Cr-Bainitic and R350HT in as-received (AR) condition from the industry. The results show that the carbide-free bainitic steel (B360) after an isothermal heat treatment offers the best mechanical performance among these steels due to a very fine, carbide-free bainitic microstructure consisting of bainitic ferrite and retained austenite laths.

Microstructure and Mechanical Properties of a Nb-Microalloyed Medium Carbon Steel Treated by Quenching-Partitioning Process

2012 ◽  
Vol 531-532 ◽  
pp. 596-599
Author(s):  
Kai Zhang ◽  
Shang Wen Lu ◽  
Yao Hui Ou ◽  
Xiao Dong Wang ◽  
Ning Zhong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Electron Microscope ◽  
Carbon Steel ◽  
Retained Austenite ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Orientation Relationships ◽  
Medium Carbon ◽  
Microstructure And Mechanical Properties

The recently developed “quenching and partitioning” heat treatment and “quenching-partitioning-tempering” heat treatment are novel processing technologies, which are designed for achieving advanced high strength steels (AHSS) with combination of high strength and adequate ductility. In present study, a medium carbon steel containing Nb was subjected to the Q-P-T process, and both the microstructure and mechanical properties was studied. The experimental results show that the Nb-microalloyed steel demonstrates high tensile strength and relatively high elongation. The microstructure of the steel was investigated in terms of scanning electron microscope and transmission electron microscope, and the results indicate that the Q-P-T steel consist of fine martensite laths with dispersive carbide precipitates and the film-like interlath retained austenite. The orientation relationships between martensite and retained austenite is as well-known Kurdjurmov-Sachs relationship and Nishiyama-Wasserman relationship.

Mechanical Properties of a Mild-Alloy Steel for Aerospace Engineering

2021 ◽  
Vol 410 ◽  
pp. 221-226
Author(s):  
Mikhail V. Maisuradze ◽  
Maxim A. Ryzhkov ◽  
Dmitriy I. Lebedev
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Strength ◽  
Aerospace Engineering ◽  
Isothermal Heat Treatment ◽  
Tempering Temperature ◽  
Optimal Heat Treatment ◽  
Treatment Conditions ◽  
Quenching And Tempering ◽  
Conventional Oil

The features of microstructure and mechanical properties of the aerospace high strength steel were studied after the implementation of various heat treatment modes: conventional oil quenching and tempering, quenching-partitioning, austempering. The dependence of the mechanical properties on the tempering temperature was determined. The basic patterns of the formation of mechanical properties during the implementation of isothermal heat treatment were considered. The optimal heat treatment conditions for the studied steel were established.

scholarly journals Effects of Heat-Treatment Temperature on the Microstructure and Mechanical Properties of Steel by MgO Nanoparticle Additions

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1707
Author(s):  
Yutao Zhou ◽  
Shufeng Yang ◽  
Jingshe Li ◽  
Wei Liu ◽  
Anping Dong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Acicular Ferrite ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Formation Mechanisms ◽  
Isothermal Heat Treatment ◽  
Mgo Nanoparticles ◽  
Intragranular Acicular Ferrite ◽  
Mgo Nanoparticle

The characteristics and formation mechanisms of intragranular acicular ferrite (IAF) in steel with MgO nanoparticle additions were systematically investigated for different isothermal heat-treatment temperatures, and its influence on mechanical properties was also clarified. The results indicate that the inclusions were finely dispersed and refined after adding MgO nanoparticles. In addition, with decreasing heat-treatment temperature, the microstructure changed from grain boundary ferrite (GBF) and polygonal ferrite (PF) to intragranular acicular ferrite. Moreover, the steel with MgO additions had excellent mechanical properties in the temperature range of 973 to 823 K and an average Charpy absorbed energies value of around 174 J at 873 K due to the significant refinement of the microstructure and nucleation of intragranular acicular ferrite.

Improved Workability of Diameter-Enlarged Process for S35C through Quenching and Tempering Heat Treatment

2019 ◽  
Vol 943 ◽  
pp. 26-33
Author(s):  
Xia Zhu ◽  
Keiji Ogi ◽  
Nagatoshi Okabe
Keyword(s):  
Heat Treatment ◽  
Charpy Impact ◽  
Hardness Test ◽  
Charpy Impact Test ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Deformation Speed ◽  
Quenching And Tempering

The hardness test, Charpy impact test, and axial expansion experiment were performed on a medium carbon steel S35C specimen typically used for shaft materials after first subjecting it to quenching and tempering heat treatment under different heating temperatures/time conditions. The effect of the tempering conditions on the mechanical properties of the specimen and the limit of the diameter-enlarged ratio used for evaluating the workability of the partial diameter-enlarged were investigated. The summary of the results are as follows: after quenching at 880 °C, a fine troostite or sorbite structure was obtained under all heat treatment conditions at heating temperatures of 550 °C to 675 °C, and heating times of 0.5 h to 1.5 h. An improvement was shown in the limit of the diameter-enlarged ratio because the quenching and tempering heat treatment led to an increase in the Charpy impact value/ductility as well as a reduction in the hardness, tensile strength, and yield strength; the partial diameter-enlarged process could be performed on the heat treated material at almost the same deformation speed as a cold-drawn material with a much lower axial pressure; it was possible to estimate the diameter-enlarged deformation behavior using the tempering parameter M. We confirmed that the quenching tempering heat treatment performed in this study facilitates the improvement of the workability of the diameter-enlarged.

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