Modeling of Growth and Dissolution of Grain Boundary Cementite in Vacuum Carburizing Process

2011 ◽  
Vol 172-174 ◽  
pp. 1177-1182
Author(s):  
Hideaki Ikehata ◽  
Kouji Tanaka ◽  
Hiroyuki Takamiya ◽  
Hiroyuki Mizuno
Keyword(s):  
Retained Austenite ◽  
Calphad Method ◽  
Metastable Equilibrium ◽  
Low Alloy Steels ◽  
Square Root ◽  
Vacuum Carburizing ◽  
Lattice Constants ◽  
Moving Interface ◽  
Alloy Steels ◽  
Carburizing Process

In order to predict microstructures during vacuum carburizing, the model which simulates not only the carbon(C) diffusion but also growth/dissolution of cementite(θ) is required. For development of a new model we applied vacuum carburizing to low alloy steels and analyzed the distribution of C and θ by GD-OES and image analysis of microstructures. The C in retained austenite(γ) phase after carburizing was also measured by lattice constants obtained from XRD. We also simulated multi-component diffusion with γ matrix and θ layer to analyze a velocity of the moving interface. The new carburizing model was proposed based on the findings, which suggest that C in γ phase at the carburizing surface is supersaturated and corresponds to C concentration for metastable equilibrium condition to graphite. The growth and dissolution of the θ follow a square root of time with the coefficients controlled by diffusion of Si in γ and Cr in θ respectively. The required parameters such as diffusivity coefficients are obtained by the CALPHAD method. The calculated C distributions and volume fractions of θ represent the experimental results.

Retained austenite and mechanical properties in bainite transformed low alloy steels

1995 ◽  
Vol 66 (10) ◽  
pp. 433-438 ◽  
Author(s):  
Gregory Haidemenopoulos ◽  
Katerina Papadimitriou
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Low Alloy Steels ◽  
Alloy Steels

Microstructure of Deformed AISI 4340 Steel

1981 ◽  
Vol 39 ◽  
pp. 316-317
Author(s):  
C. N. Sastry
Keyword(s):  
Retained Austenite ◽  
Tensile Specimen ◽  
Argon Atmosphere ◽  
Low Alloy Steels ◽  
Low Alloy Steel ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Thin Foils ◽  
Alloy Steels ◽  
Aisi 4340

The microstructure of low alloy steels has been studied by several investigators. They have shown that when low alloy steel is quenched from 1200°C, the martensite formed exhibits packets of dislocated laths containing auto tempered carbide within the laths and thin films of retained austenite at the lath boundaries. The present study is aimed to investigate the effects of deformation on microstructure of AISI 4340 steel. Tensile plate specimens were austenitized at 1200°C for 1 hr in argon atmosphere, oil quenched and tempered at 180°C for 1 hr. Following the heat treatment, these specimens were uniaxially pulled in tension and thin foils for TEM were taken from the surface of broken tensile specimen. Foils were also prepared from undeformed region. These foils were observed at 100 kv in Hitachi HU 11B microscope.

TRIP-Assisted Multiphase Steels with Niobium Additions. Microstructures and Properties

2005 ◽  
Vol 500-501 ◽  
pp. 445-452 ◽  
Author(s):  
V. Andrade-Carozzo ◽  
Pascal J. Jacques
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Ferrite Matrix ◽  
Low Alloy Steels ◽  
Thermomechanical Process ◽  
Alloy Steels ◽  
Cold Rolled ◽  
Nb Addition ◽  
Strength And Ductility ◽  
Multiphase Steels

It seems completely clear that the combination within the same microstructure of various steel phases (ferrite, bainite, martensite) and the existence of the TRIP effect (i.e. a mechanically induced martensitic transformation) improves in a large way the properties of strength and ductility of low-alloy steels. TRIP-aided multiphase steels have been studied for several years and arouse a growing industrial interest. This project deals with the influence of a large Nb addition on the microstructure and mechanical properties of TRIP-assisted multiphase steels. It is shown that Nb influences in a large way the different phase transformations as well as the recrystallisation of the ferrite matrix occurring during the heat-treatment of cold-rolled TRIP-aided steels. As a consequence, the mechanical properties also depend on the parameters of the thermomechanical process and on the content and stability of the retained austenite.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

Materials for bullet core

2020 ◽  
Vol 2020 (10) ◽  
pp. 8-21
Author(s):  
A. G. Kolmakov ◽  
◽  
I. O. Bannykh ◽  
V. I. Antipov ◽  
L. V. Vinogradov ◽  
...  
Keyword(s):  
High Speed ◽  
Bending Strength ◽  
Low Alloy Steels ◽  
Hard Alloys ◽  
Small Arms ◽  
Alloy Steels ◽  
Materials Used ◽  
Basic Ideas ◽  
New Generation ◽  
Natural Composite

he basic ideas about the process of introducing cores into protective barriers and the most common core patterns and their location in conventional and sub-caliber small arms bullets are discussed. The materials used for manufacture of cores are analyzed. It is concluded that for mass bullets of increased armor penetration the most rational choice can be considered the use of high-carbon low-alloy steels of a new generation with a natural composite structure and hardness of up to 70 HRC. For specialized armor-piercing bullets, cores made from promising economically-alloyed high-speed steels characterized by a high complex of «hardness—bending strength» are better alternative than ones made of hard alloys or tungsten alloys.

UNIFLUX VCM 125

Alloy Digest ◽  
1978 ◽  
Vol 27 (1) ◽  
Keyword(s):  
Carbon Dioxide ◽  
Fracture Toughness ◽  
Weld Metal ◽  
Heat Treating ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Electrode Wire ◽  
Molybdenum Steel ◽  
Alloy Steels ◽  
Welding Electrode

Abstract UNIFLUX VCM 125 is a continuous flux-cored welding electrode (wire) that is used to deposit 1 1/4% chromium-1/2% molybdenum steel for which it was developed. Welding is protected by a shielding atmosphere of 100% carbon dioxide. This electrode also may be used to weld other low-alloy steels and carbon steels; however, the weld metal may differ somewhat from 1 1/4% chromium-1/2% molybdenum because of weld-metal dilution. When Uniflux VCM 125 is used to weld 1 1/4% chromium-1/2% molybdenum steel, it provides 95,000 psi tensile strength at 70 F and 24 foot-pounds Charpy V-notch impact at 40 F. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: SA-340. Producer or source: Unicore Inc., United Nuclear Corporation.

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