scholarly journals Correlation Between Granule Strength and Green Strength at Compaction of Cemented Carbide Powder Materials

2021 ◽  
Author(s):  
Kristin Salmi ◽  
Erik Könberg ◽  
Hjalmar Staf ◽  
Per-Lennart Larsson
Keyword(s):  
Practical Importance ◽  
Hard Metal ◽  
Strength Properties ◽  
Coefficient Of Determination ◽  
Carbide Powder ◽  
Powder Materials ◽  
Metal Powders ◽  
Green Strength ◽  
Granule Strength ◽  
Point Bend

AbstractThe correlation between granule strength and green strength of hard metal powders is examined. The approach is based on experiments and numerics. In the latter case, a Design of Experiment software is used. The granule strength of the powder (particle) is determined by GFP-measurements (“Granularfestigkeits-Prüfsystem”). During this test, a single particle is pressed from one side until breakage. The corresponding measurements of the green strength are done using three-point bend (3PB) testing. The experimental results show that the pressing agent has a strong influence on the behavior of both quantities. The statistical evaluation shows that the relation between the two strength properties is very close to linear with coefficient of determination R2 taking on the value 0.97. This of course indicates that it is possible to get information about one of the properties for a similar set of materials by experimentally determining the other one. This is of substantial practical importance as for one thing it can limit the amount of testing required. Even though the present investigation is pertinent to hard metal powders, the results could be of value for many other types of powder materials.

scholarly journals On the Relation Between Pressing Energy and Green Strength at Compaction of Hard Metal Powders

2021 ◽  
Author(s):  
Kristin Salmi ◽  
Hjalmar Staf ◽  
Per-Lennart Larsson
Keyword(s):  
Practical Importance ◽  
Hard Metal ◽  
Coefficient Of Determination ◽  
Powder Materials ◽  
Metal Powders ◽  
Punch Force ◽  
Green Strength ◽  
Similar Materials ◽  
Uniaxial Compaction ◽  
Complicated Geometries

AbstractThe relation between pressing energy and green strength is examined experimentally and numerically using a commercially available design of experiment (DOE) software, at compaction of five hard metal powder materials. This is of substantial practical importance, in particular at pressing of complicated geometries when high values on the green strength is necessary. The compaction energy is here experimentally determined at uniaxial compaction of a cylindrical die, filled with powder material, by measuring punch force and compression. The corresponding measurements of the resulting green strength are performed using standard three-point bend (3PB) testing. The statistical analysis of the results shows that the relation between the two properties, pressing energy and green strength, is very close to a linear fit with the coefficient of determination R2 taking on the value 0.92. This suggests that the pressing energy is an important quantity for reaching a target value on the green strength and the linear relation is certainly convenient in particular when compaction of similar materials is at issue. In parallel with the experimental work finite element calculations are performed in order to evaluate the effect from friction between the powder and the die wall, and it was found that this feature has a limited effect on the pressing energy when similar materials are at issue and is not detrimental for the usefulness of the present correlation approach.

Investigation of pre-sprayed powders for electric contact welding

2020 ◽  
pp. 143-149
Author(s):  
Dinar R. Masalimov ◽  
Roman R. Galiullin ◽  
Rinat N. Sayfullin ◽  
Azamat F. Fayurshin ◽  
Linar F. Islamov
Keyword(s):  
Adhesion Strength ◽  
Electrical Contact ◽  
Research Purpose ◽  
Flame Spraying ◽  
Powder Materials ◽  
Electric Contact ◽  
Metal Powders ◽  
Unstable Flow ◽  
Gas Flame ◽  
Contact Welding

There are a number of difficulties in the electrical contact welding of powder materials: shedding of powder from the surface of a cylindrical part, impossibility of hardening the layer during welding due to flushing of the powders with coolant and unstable flow of powder into the welding zone. One solution is pre-spraying the powder in some way. (Research purpose). The research purpose is investigating the possibility of electric contact welding of metal powders preliminarily sprayed by a gas-flame method, namely, adhesion strength and losses during preliminary gas-flame spraying of powders. (Materials and methods) Powders of grades PG-NA-01, PrKhIIG4SR, PRZh3.200.28 were sprayed onto flat samples of St3 steel, polished to a roughness of Ra 1.25. The strength of powder adhesion to the base was studied by the cut method. (Results and discussion) The percentage loss of the powder as a whole is 3-23 percent for all the distances studied. The greatest powder losses appear at a distance of more than 180 millimeter from the tip of the burner for powders of grades PG-NA-01 and PrKhIIG4SR. The smallest powder losses were observed for PrZh3.200.28 powder, which totaled 3-7 percent. The maximum adhesion strength of the sprayed powders to the surface was 22.1 megapascals' when spraying the PG-NA-01 powder. The adhesion strength of powders of the grades PrKhIIG4SR and PrZh3.200.28 is small and amounts to 0.2-3 megapascals'. (Conclusions) The use of preliminary flame spraying of powders for their further electric contact welding is possible using PG-NA-01 grade powder, while the best adhesion to the base (that is more than 20 megapascals') is achieved with a spraying distance of 120-140 millimeter. The smallest powder losses during flame spraying are achieved at a spraying distance of 100-160 centimeters', at which the powder loss for the studied grades was 4-12 percent.

scholarly journals Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

Weldability: Effect of Alloying Element Sc, Mn, and Zr on Alloys of the Al-Mg-Sc-Mn-Zr System

2019 ◽  
Author(s):  
V. I. Lukin
Keyword(s):  
Aluminum Alloys ◽  
Practical Importance ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Mg Alloy ◽  
Alloying Element ◽  
Processing Properties ◽  
Alloys Of The Al ◽  
Effect Of Alloying

Scandium in aluminum alloys behaves as the most efficient modifier of the structure of the material and as an agent suppressing recrystallization. This unique behavior of scandium in alloys of the Al-Mg system greatly increases the strength characteristics, whilst retaining on a higher level the ductility and processing properties of deformed semi-finished products. This article describes the effect of complex alloying the Al-6.3% Mg alloy with scandium, manganese and zirconium on the weldability and strength properties of the material is of considerable scientific and practical importance.Investigations.

Influence of Physical Properties of B4C Powder on the Strength Properties of the Ceramics Manufactured by SPS Sintering

2015 ◽  
Vol 1085 ◽  
pp. 312-315
Author(s):  
Oleg L. Khasanov ◽  
Edgar S. Dvilis ◽  
Zulfa G. Bikbaeva ◽  
Valentina V. Polisadova ◽  
Alexey O. Khasanov ◽  
...  
Keyword(s):  
Physical Properties ◽  
Boron Carbide ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Strength Properties ◽  
Carbide Powder ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Determining Factor ◽  
Sps Sintering

Ceramics samples in the form of a parallelepiped with high strength characteristics have been made. For the manufacture of the ceramics samples a powder mixture from submicron В4С powder with additives (1 wt%, 5 wt%, 10 wt%) of boron carbide nanopowder was used. The physical properties of the powder mixtures and strength properties of sintered ceramics have been studied. It was shown that the use of submicron fractions of the boron carbide powder together with nanoadditives is a determining factor in the formation of dense fine-grained structure providing improved physical and mechanical properties of the ceramics.

Rheological Behaviour of Hard-Metal Carbide Powder Suspensions at High Shear Rates

2000 ◽  
Vol 20 (4) ◽  
Author(s):  
B. Hausnerová ◽  
P. Sáha ◽  
J. Kubát ◽  
T. Kitano ◽  
J. Becker
Keyword(s):  
Rheological Behaviour ◽  
Hard Metal ◽  
Carbide Powder ◽  
High Shear ◽  
Metal Carbide ◽  
Shear Rates ◽  
High Shear Rates

Effect of Die Temperature on Mechanical Properties of Hot Pressed P/M Parts

2010 ◽  
Vol 638-642 ◽  
pp. 1802-1810
Author(s):  
Abolfazl Babakhani ◽  
Ali Haerian
Keyword(s):  
Room Temperature ◽  
Strength Properties ◽  
Metal Contacts ◽  
Powder Morphology ◽  
Particle Spacing ◽  
Green Strength ◽  
Flow Problems ◽  
Metal Metal ◽  
Different Temperatures ◽  
Die Temperature

In conventional warm compaction, both powder and die are heated to a certain temperature during compaction. This is a technique for producing P/M compacts with higher green and sintered strength as compared to room temperature pressing. However, there is a certain limit to powder temperature due to flow problems at higher temperatures. Heating the die above this practical limit can further improve properties. In this work, the effect of die temperature on green and sintered properties of Astaloy CrM powder has been investigated. Here, the powder at 135 oC was fed to the die at different temperatures. Density and strength for samples in green and sintered conditions were evaluated for two compaction pressures of 500 and 650MPa and temperatures ranging from ranging from 135 to 165 oC. Comparison of samples compressed at room temperature showed marked improvement in density and strength properties. A 22% increase in density, as well as 40% increase in green strength was observed. Tensile and impact strengths were improved by about 10% and 20% respectively. SEM micrographs showed more rounded pores and hence reduced stress raising sites. The improvement in properties can be mainly attributed to changes in powder morphology and die wall lubrication due to migration of hot lubricant from interparticle space to die walls. The latter will reduce particle spacing and bring about more intimate metal-metal contacts as well as better lubrication on die walls.

Prediction of Ductile Crack Growth from Ductility of Steel

2007 ◽  
Vol 539-543 ◽  
pp. 2186-2191 ◽  
Author(s):  
Mitsuru Ohata ◽  
Takuya Fukahori ◽  
Fumiyoshi Minami
Keyword(s):  
Mechanical Properties ◽  
Crack Initiation ◽  
Crack Growth ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Local Strain ◽  
Strength Properties ◽  
Ductile Crack ◽  
Ductile Crack Growth ◽  
Point Bend

This study pays attention to reveal the material properties that control resistance curve for ductile crack growth (CTOD-R curve) on the basis of the mechanism for ductile crack growth, so that the R-curve could be numerically predicted only from those properties. The crack growth tests using 3-point bend specimens with fatigue pre-crack were conducted for two steels that have different ductile crack growth resistance with almost the same CTOD level for crack initiation, whereas both steels have the same “Mechanical properties” in terms of strength and work hardenability. The observation of crack growth behaviors provided that different mechanisms between ductile crack initiations from fatigue pre-crack and subsequent growth process could be applied. It was found that two “Mechanical properties” associated with ductile damage of steel could mainly influence CTOD-R curve; one is a resistance of ductile crack initiation estimated with critical local strain for ductile cracking from the surface of notched specimen, and the other one is a dependence of stress triaxiality on ductility obtained with circumferentially notched round-bar specimens. The damage model for numerically simulating the R-curve was proposed taking the two “ductile properties” into account, where ductile crack initiation from crack-tip was in accordance with critical local strain based criterion, and subsequent crack growth GTN (Gurson-Tvergaard-Needleman) based triaxiality dependent damage criterion. The proposed model accurately predicted the measured R-curve for the two steels used with the same “strength properties” through ductile crack initiation to growth.

scholarly journals Statistical Analysis of Results Obtained in the Hardening Surface of the Metal Powder Materials with Optical Radiation Impulses

2015 ◽  
Vol 20 (2) ◽  
pp. 79-85
Author(s):  
Ioan Virca
Keyword(s):  
Statistical Analysis ◽  
Metal Powder ◽  
Voltage Pulse ◽  
Optical Radiation ◽  
Experimental Program ◽  
Energy Sources ◽  
Powder Materials ◽  
Metal Powders ◽  
Analysis Of Results

Abstract The paper presents how is processed the data resulted from application of pulsed optical superficial treatments on surfaces of materials made of metal powders. The parameters of the electrotechnological regime work are variable in the experimental program, namely the distance between the axis focal energy sources and surfaces play, the number of energy pulses applied to the voltage pulse of optical radiation, which causes a statistical analysis more complex, after which it will precise drawing lessons that will lead to a calculation microhardness model in the superificial layer of material.

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