Production of WC-15Co ultrafine-grained hard alloy from powder obtained by VK15 alloy waste spark erosion in water

2020 ◽  
pp. 4-16
Author(s):  
M. I. Dvornik ◽  
E. A. Mikhailenko
Keyword(s):  
Carbon Content ◽  
Dendritic Structure ◽  
Cobalt Content ◽  
Cemented Carbide ◽  
Grain Structure ◽  
Vacuum Sintering ◽  
Initial Alloy ◽  
Ultrafine Grained ◽  
Spark Erosion ◽  
Grain Diameter

The study covers the possibility of WC-15Co ultrafine cemented carbide production from powder obtained by spark erosion (SE) of VK15 cemented carbide waste in water. As a result of SE in an oxygen-containing liquid (H2O), the carbon content in the resulting powder decreases from 5.3 to 2.3 %. When the powder is heated to 900 °C in vacuum, the carbon content decreases to 0.2 % due to the presence of oxygen. The powder obtained consists of WC, W2C and Co phases. Particles have a dendritic structure consisting of newly formed tungsten-containing grains and cobalt interlayers. The controlled removal of oxygen and carbon replenishment in the resulting powder were carried out by heating in the CO atmosphere to t = = 900 °C. The processed powder has a required phase composition (WC + Co) and carbon content (5.3 %). Particles retain their spherical shape after carbon replenishment. WC grains in particles become plate-shaped with the space between them filled with cobalt. The average grain diameter is smaller than in the initial alloy. The vacuum sintering of the resulting powder at 1390 °C made it possible to obtain WC–15Co ultrafine-grained cemented carbide with an average WC grain diameter of 0.44 μm. It is several times smaller than the average grain diameter in the initial alloy (1.8 μm). Most grains retain their plate shape. The resulting alloy combines high hardness (1620 HV), increased fracture toughness (13.2 MPa·m1/2) and strength (1920 MPa) due to its fine-grain structure and 15 % cobalt content. In terms of the set of its properties, this alloy is not inferior to analogues obtained by other methods.

Microstructural Changes of Welded Zn-AI Alloy

1994 ◽  
Vol 367 ◽  
Author(s):  
Yao Hua Zhu
Keyword(s):  
Phase Transformation ◽  
Early Stage ◽  
Dendritic Structure ◽  
Metastable Phases ◽  
Grain Structure ◽  
Al Alloy ◽  
Cast State ◽  
Microstructural Changes ◽  
Fine Grain ◽  
Ageing Processes

AbstractExtruded eutectoid Zn-Al alloy was welded by a melt of the same eutectoid alloy. Two different microstructures were observed in the joint part and the bulk of the welded alloy. Typical dendritic structure of as cast Zn-Al alloy was observed in the joint part of the welded alloy. The bulk ofthe welded Zn-Al alloy appeared as fine grain structure. Two different metastable phases η'T decomposed from η's of chilled as cast state and η'E of extruded state were found to be unstable during early stage of ageing. A four phase transformation occurred after the decompositions of these two metastable phases of η'T. Microstructures of both joint part and bulk of the welded alloy were investigated parallely during ageing processes.

Grain Refinement and Deformation Behavior of Ultrafine Grained Pd and Pd-Ag Alloys Produced by HPT

2008 ◽  
Vol 584-586 ◽  
pp. 182-187
Author(s):  
Lilia Kurmanaeva ◽  
Yulia Ivanisenko ◽  
J. Markmann ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Materials Science ◽  
High Pressure Torsion ◽  
Uniform Elongation ◽  
Grain Structure ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Ultrafine Grained ◽  
Ultrafine Grain Structure

Investigations of mechanical properties of nanocrystalline (nc) materials are still in interest of materials science, because they offer wide application as structural materials thanks to their outstanding mechanical properties. NC materials demonstrate superior hardness and strength as compared with their coarse grained counterparts, but very often they possess a limited ductility or show low uniform elongation due to poor strain hardening ability. Here, we present the results of investigation of the microstructure and mechanical properties of nc Pd and Pd-x%Ag (x=20, 60) alloys. The initially coarse grained Pd-x% Ag samples were processed by high pressure torsion, which resulted in formation of homogenous ultrafine grain structure. The increase of Ag contents led to the decrease of the resulted grain size and change in deformation behavior, because of decreasing of stacking fault energy (SFE). The samples with larger Ag contents demonstrated the higher values of hardness, yield stress and ultimate stress. Remarkably the uniform elongation had also increased with increase of strength.

scholarly journals Effect of Heat Treatment on the Microstructure and Properties of Ultrafine WC–Co Cemented Carbide

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1302
Author(s):  
Zhongnan Xiang ◽  
Zhanjiang Li ◽  
Fa Chang ◽  
Pinqiang Dai
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Service Life ◽  
Treatment Process ◽  
Cutting Conditions ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Heat Treatment Process ◽  
Microstructure And Properties ◽  
Ultrafine Grained

In this paper, the effect of heat treatment on the microstructure and properties of a 0.8 μm WC–10%Co ultrafine cemented carbide was studied. The results show that the microstructural differences in ultrafine WC–Co cemented carbides without and with heat treatment are mainly reflected in the Co phase. For conventional cemented carbides, the hardness and wear resistance can be increased only at the expense of the toughness and strength. An ultrafine-grained WC–Co cemented carbide with good hardness and toughness can be obtained by strengthening the Co phase through an appropriate heat treatment process, and the service life of the ultrafine-grained WC–Co cemented carbide can be improved under actual cutting conditions.

Comparison of Microstructure and Mechanical Properties of Semi-Solid Castings Produced Using Billets Made by EMS and SEED

2014 ◽  
Vol 217-218 ◽  
pp. 332-339 ◽  
Author(s):  
Xiao Kang Liang ◽  
Da Quan Li ◽  
Pascal Côté ◽  
Stephen P. Midson ◽  
Qiang Zhu
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Dendritic Structure ◽  
Casting Process ◽  
Grain Structure ◽  
High Quality ◽  
Microstructure And Mechanical Properties ◽  
Grain Structures ◽  
Heat Treated ◽  
Semi Solid

The spheroidal grains in billets used for semi-solid casting are generally manufactured by electromagnetic stirring (EMS) during the casting process. This method however, is not economically applicable for small quantities of the thixo billets. Swirled Enthalpy Equilibration Device (SEED) has been developed as a rheocasting process, and the SEED process is of interest for developing new thixo alloys, as well as for optimizing the thixocasting processes for high quality components. The objective of this paper is to compare the microstructure and mechanical properties of aluminum alloy 319s billets and castings produced using EMS and SEED feed materials. The experimental results show that for as-cast billets made from SEED process, a well-developed spheroidal grain structure is distributed throughout the cross-section of the billet, while for as-cast EMS billets, the grain structure is inhomogeneous, i.e., a dendritic structure was present adjacent to the surface of the billet, while a uniform, spheroidal structure was present at the centre. After the thixocasting process, however, the both SEED and EMS billets have well-developed, spheroidal grain structures. Mechanical properties of thixocast and T61 heat treated components are comparable for the both SEED and EMS billets.

Effect of Cold Isostatic Pressing on the Mechanical Properties of WC-8Co Cemented Carbide for Friction Stir Welding Tool

2014 ◽  
Vol 563 ◽  
pp. 107-111
Author(s):  
Chen Zhang ◽  
Bing Liang Liang ◽  
Yun Long Ai ◽  
Chang Hong Liu
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Relative Density ◽  
Cold Isostatic Pressing ◽  
Cemented Carbide ◽  
Vacuum Sintering ◽  
Pressing Method ◽  
Isostatic Pressing ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties

WC-8Co cemented carbide specimens were prepared via vacuum sintering. The effects of cold isostatic pressing (CIP) on microstructure and mechanical properties were investigated. The results show that only WC and Co3W3C (γ-phase) were detected by XRD without any else phases, even though Co. Dense WC-8Co cemented carbide samples were obtained and relative density reached over 98%. The pressing method, instead of pressure, took an important role in the mechanical properties of WC-8Co cemented carbide. KIC and TRS of WC-8Co cemented carbide were improved at least 27% and 24%, respectively, by the use of CIP. WC-8Co cemented carbide with excellent mechanical properties (HRA>93.5, KIC>11MPa·m1/2, TRS>870MPa) was obtained by using CIP.

Influence of the conditions of casting and heat treatment on the structure and mechanical properties of the AlMg10 alloy

2017 ◽  
Vol 1 (83) ◽  
pp. 26-32
Author(s):  
P. Kordas
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Liquid State ◽  
Precipitation Hardening ◽  
Solidification Rate ◽  
Dendritic Structure ◽  
Grain Structure ◽  
Alloy Castings ◽  
Die Castings ◽  
The Impact

Purpose: Assessment of the possibilities of shaping the structure and improvement of mechanical properties of casting from AlMg10 alloy through a selection of casting technology and precipitation hardening. Design/methodology/approach: the work evaluated the impact of casting and heat treatment technology on the mechanical properties and structure of AlMg10 alloy castings. The tests were performed on 200 mm × 100 mm × 25 mm plate castings produced by gravity casting methods for sand and metal moulds and by a liquid state press moulding technology. Castings made with these technologies solidify in substantially different heat- evaporation conditions and exhibit varying degrees of primary structure fragmentation. Metallographic and strength tests were performed on raw castings and after heat treatment. Findings: The changes in the morphology and size of primary crystals and the dispersion of the reinforcing phase according to the casting solidification rate and the precipitation hardening treatment were analyzed. Solidifying castings in the form of sand show a globular structure, whereas in die and press castings, a typically dendritic structure occurs, with the dendritic crystals in pressed castings being much smaller in size than the die castings. In castings which were not heat-treated, the reinforcing phase of Al3Mg2 occurs in interdendritic spaces, and its dispersion increases with the rate of cooling. After supersaturation and ageing treatments, the phase α has a grain structure in all samples. The largest dispersion of reinforcing molecules is characterized by press castings. In a raw state, the highest mechanical properties are shown by castings made in the form of sand and the method of pressing in a liquid state. Heat treatment of AlMg10 alloy castings significantly influences the increase of mechanical indexes in all castings investigated. The highest features of Rm are approx. 330 MPa and A5 above 10% is obtained in castings made by the press method. Research limitations/implications: Particular attention should be paid to the avoidance of the effects of slag inclusion, shrinkage and magnesium oxidation during casting of AlMg10 alloys. In die castings of a plate type, due to own stresses, a significant decrease in mechanical properties occurs. Practical implications: The most advantageous mechanical properties of AlMg10 alloy castings are obtained by using liquid-state pressing technology. In addition, this technology makes it possible to produce thin-walled castings of high dimensional accuracy, high air- tightness, fine grain structure, lack of surface defects and low roughness. Originality/value: The paper presents the possibility of improving the mechanical properties of AlMg10 castings by applying heat treatment. It has been proven that the casting method has a significant effect on the mechanical properties of the castings.

The Effect of Grain Size and Cobalt Content on the Wear of Ultrafine Cemented Carbide Tools

2014 ◽  
Vol 875-877 ◽  
pp. 1344-1351
Author(s):  
Jian Bing Cheng ◽  
Si Qin Pang ◽  
Xi Bin Wang ◽  
Xi Bin Wang ◽  
Chen Guang Lin
Keyword(s):  
Grain Size ◽  
Tool Wear ◽  
Tool Life ◽  
Wear Mechanism ◽  
Wear Mechanisms ◽  
High Strength Steels ◽  
Cobalt Content ◽  
Cemented Carbide ◽  
Cemented Carbide Tools ◽  
Cutting Speeds

This work contributes to a better understanding of wear mechanisms of ultrafine cemented carbide cutting tools used in turning operation of superalloy and high strength steels at high cutting speeds. The main objective of this work is to verify the influence of grain size and the cobalt content of ultrafine cemented carbide tools on tool life and tool wear mechanism. The main conclusions are that grain size and the cobalt content of ultrafine cemented carbide tools strongly influence tool life and tool wear involve different mechanisms. The wear mechanisms of different grain size and the cobalt content of ultrafine cemented carbide tools observed on the rake face at these conditions were adhesion and notch, at the end of tool life, adhesion was the main wear mechanism at higher cutting speeds.

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