scholarly journals Effect of Tempering Conditions on Secondary Hardening of Carbides and Retained Austenite in Spray-Formed M42 High-Speed Steel

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3714 ◽  
Author(s):  
Bowen Liu ◽  
Tian Qin ◽  
Wei Xu ◽  
Chengchang Jia ◽  
Qiuchi Wu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Carbide Phase ◽  
Retained Austenite ◽  
High Speed ◽  
Bending Strength ◽  
High Speed Steel ◽  
Secondary Hardening ◽  
Electron Backscattered Diffraction ◽  
Scanning Calorimetry ◽  
Austenite Content

In this study, the effect of tempering conditions on microstructure, grain size, and carbide phase compositions of spray-formed high-speed steel after quenching at 1180 °C was studied. The influence of carbide phase, size of carbides, and retained austenite content on secondary hardening of the steel was analyzed by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), electron backscattered diffraction (EBSD), and differential scanning calorimetry (DSC); the hardness, microhardness of carbide, and bending strength were tested. The results show that M3C, M6C, M7C3, and MC carbides may precipitate at different tempering temperatures and the transformation of the retained austenite can be controlled by tempering. The phase composition of carbides, microstructure, and retained austenite content strongly influences the performance characteristics of M42 high-speed steel after tempering. In contrast, the secondary carbides produced by tempering thrice at 540 °C are mainly M6C carbides rich in W and Mo elements, and the content of retained austenite is effectively reduced. At this stage, the Rockwell hardness reaches 67.2 HRC, bending strength reaches 3115 MPa, and the properties and microstructure are optimal.

Sintering of AISI M2 High Speed Steel with the Addition of NbC

2012 ◽  
Vol 727-728 ◽  
pp. 90-95 ◽  
Author(s):  
Alexandre Wentzcovitch ◽  
Francisco Ambrozio Filho ◽  
Luís Carlos Elias da Silva ◽  
Maurício David Martins das Neves
Keyword(s):  
Differential Scanning Calorimetry ◽  
Electron Microscope ◽  
High Speed ◽  
Sintering Temperature ◽  
Niobium Carbide ◽  
High Speed Steel ◽  
Vacuum Melting ◽  
Scanning Calorimetry ◽  
Steel Aisi ◽  
Scanning Electron

The influence of adding 6 wt% (NbC) niobium carbide on the sintering temperature and microstructure of high speed steel - AISI M2(0.87% C, 5.00% Mo, 6.00% W, 4,00% Cr, 2.00% V and Fe bal.) powder was studied. The starting material was obtained by vacuum melting followed by atomization in water. The samples were axially cold compacted in a cylindrical matrix and then vacuum sintered at 1250 and 1350 °C. Dilatometry and differential scanning calorimetry measurements indicated an increase in sintering temperature with addition of niobium to the AISI M2steel. Optical and scanning electron microscope observations revealed a microstructure with uniformly distributed niobium carbides.

Effect of Spark Plasma Sintering on the Microstructure Evolution and Properties of M3:2 High-Speed Steel

2014 ◽  
Vol 788 ◽  
pp. 329-333
Author(s):  
Rui Zhou ◽  
Xiao Gang Diao ◽  
Jun Chen ◽  
Xiao Nan Du ◽  
Guo Ding Yuan ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Spark Plasma Sintering ◽  
High Speed ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Speed Steel ◽  
Continuous Heating ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact

Effects of sintering temperatures on the microstructure and mechanical performance of SPS M3:2 high speed steel prepared by spark plasma sintering was studied. High speed steel sintering curve of continuous heating from ambient temperature to 1200°C was estimated to analyze the sintering processes and sintering temperature range. The sintering temperature within this range was divided into groups to investigate hardness, relative density and microstructure of M3:2 high-speed steel. Strip and quadrate carbides were observed inside the equiaxed grains. SPS sintering temperature at 900°C can lead to nearly full densification with grain size smaller than 20μm. The hardness and bending strength are higher than that of the conventionally powder metallurgy fabricated ones sintered at 1270°C. However, fracture toughness of the high speed steel is lower than that of the conventional powder metallurgy steels. This can be attributed to the shape and distribution of M6C carbides which reduce the impact toughness of high speed steels.

Phase Reactions During Sintering of M3/2 Based Composites with WC Additions

2013 ◽  
Vol 58 (3) ◽  
pp. 703-708 ◽  
Author(s):  
M. Madej
Keyword(s):  
Grain Boundary ◽  
Carbide Phase ◽  
High Speed ◽  
Brinell Hardness ◽  
High Speed Steel ◽  
Hardness Test ◽  
Edx Analysis ◽  
Boundary Film ◽  
Dilatometric Studies ◽  
Cold Pressed

Abstract Attempts have been made to describe the influence of WC additions on properties of M3/2 high speed steel (HSS) based composites. The powder compositions used to produce skeletons for further infiltration were M3/2, M3/2+10%WC and M3/2+30%WC. The powders were cold pressed at 800 MPa. The green compacts were subsequently sintered for 60 minutes at 1150°C in vacuum. These as-sintered specimens were used for copper infiltration. A qualitative EDX analysis revealed presence of both MC type vanadium-rich carbides and M6C type tungsten and iron rich carbides. In specimens containing 10 and 30% WC the carbide phase was uniformly distributed within copper-rich regions. The WC monocarbide reacts with the surrounding HSS matrix and forms a carbide grain boundary film. The microstructural observations of the as-sintered specimens was followed by Brinell hardness test and supplemented with dilatometric studies.

scholarly journals Non-equilibrium solidification and microsegregation in centrifugally cast high speed steel for rolls

2018 ◽  
Vol 54 (1) ◽  
pp. 59-66 ◽  
Author(s):  
U. Klancnik ◽  
B. Kosec ◽  
P. Mrvar ◽  
J. Medved
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Light And Electron Microscopy ◽  
High Speed Steel ◽  
Scanning Calorimetry ◽  
Centrifugally Cast ◽  
Eutectic Carbides ◽  
Thermo Calc Software ◽  
Equilibrium Solidification ◽  
Non Equilibrium

When regarding as-cast microstructures of highly alloyed metals, microsegregation of alloying elements is a common feature resulting from non-equilibrium conditions during solidification. The aim of this work is to predict the occurrence and severity of microsegregation in highly alloyed, centrifugally cast high speed steel used for rolls. The prediction was performed using thermodynamic Scheil-Gulliver modelling with Thermo-Calc software. The modelled predictions were then compared with differential scanning calorimetry, X-ray diffraction, light and electron microscopy with energy dispersive spectroscopy, all performed on an as-cast roll shell. Results show that chromium, molybdenum and vanadium have the highest tendency to microsegregation. Vanadium tends to form negative microsegregation, while molybdenum and chromium form positive microsegregation. Scanning electron microscopy revealed the presence of complex eutectic carbides, confirming the Scheil-Gulliver non-equilibrium solidification path via two main successive eutectic reactions.

EFFECT OF BORON CONTENT ON HIGH-TEMPERATURE OXIDATION RESISTANCE OF B-BEARING HIGH-SPEED STEEL

2020 ◽  
Vol 27 (12) ◽  
pp. 2050023
Author(s):  
YINGHUA LIN ◽  
HUI LI ◽  
JIANG JU ◽  
CHANGCHUN JIANG ◽  
YONGPING LEI ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxide Film ◽  
Oxidation Resistance ◽  
Retained Austenite ◽  
High Speed ◽  
Boron Content ◽  
Unit Area ◽  
High Speed Steel ◽  
Mass Gain ◽  
Temperature Oxidation

The oxidation behavior of B-bearing high-speed steel was studied at 923[Formula: see text]K. The results showed that the as-cast microstructure of 1.0 wt.%B high-speed steel was composed of pearlite + ferrite + M7(C, B)3 + M2(B, C). When the boron content increased, the microstructure gradually changed into martensite + retained austenite + netlike M2(B, C) + M[Formula: see text](C, B)6 + M7(C, B)3. The cyclic oxidation of B-bearing high-speed steel at K followed parabolic rule. The unit area mass gain of 1 wt.%B high-speed steel was 4.2 g/m2 after 923 K/250 h oxidation, and the unit area mass gain of 3 wt.%B high-speed steel was only 3.5 g/m2. The oxidation of boron element formed B2O3, which was mainly enriched at the interface of the oxide film/matrix. B2O3 flowed in the oxide film at high temperature and was easy to fill the defect. B2O3 was easy to form B2O3-SiO2 borosilicate with SiO2. The more boron content was, the more favorable it was to form B2O3-SiO2 borosilicate oxide layer rich in B2O3 and the more favorable it was to spread in the oxide film, so that the oxidation resistance of B-bearing high-speed steel could be remarkably improved.

FAGERSTA D-950

Alloy Digest ◽  
1976 ◽  
Vol 25 (9) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Chemical Analysis ◽  
Physical Properties ◽  
High Speed ◽  
High Speed Steel ◽  
Heat Treating ◽  
Secondary Hardening ◽  
Excellent Response ◽  
Economic Considerations

Abstract FAGERSTA D-950 is a high-speed steel that combines economic considerations in a properly balanced chemical analysis. An optimum carbon-vanadium ratio provides a high attainable hardness along with good mechanical properties. Its wide hardening range and excellent response to secondary hardening is rather unique and can offer some advantages in heat treatment. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-307. Producer or source: Fagersta Steels Inc..

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