scholarly journals EVALUATION OF THE MECHANICAL PROPERTIES OF DIFFUSION LAYER IN THE PROCESS OF MICROARC STEEL VANADATION

2018 ◽  
Vol 61 (8) ◽  
pp. 625-630 ◽  
Author(s):  
M. S. Stepanov ◽  
Yu. M. Dombrovskii ◽  
L. V. Davidyan
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Diffusion Layer ◽  
Total Duration ◽  
Thermochemical Treatment ◽  
High Energy ◽  
Solid Solution Hardening ◽  
Material Surface ◽  
Dispersion Component ◽  
Carbide Particles

Traditional processes of thermochemical treatment of steel have a longer duration, so there are proposed the new methods of intensification of diffusion saturation with high-energy impacts on the material surface. In the process of micro-arc alloying the steel product is immersed in a container filled with powder of coal, and is heated by passing electric current. In a powder environment, microdischarges are formed, which are concentrated around the product and create an area of gas discharge with the formation of a carbonaceous gas environment, which enables carburizing of steel. The application of coating containing diffusant allows forming coating of a carbide type due to simultaneous carbon diffusion into alloying elements. The influence of micro-arc surface alloying of steel with vanadium on mechanical properties of diffusion coatings is studied, and the primary mechanism of steel hardening at microarc alloying is revealed. Cylindrical samples of 20 steel were used; the source diffusant was a powder of ferrovanadium. Current density on the sample surface was 0.3 A/cm2, total duration of the process was 3 min. The mechanical properties of coatings were evaluated by means of indentation using pyramidal indenter, at loads of 2.5 mN, 20 mN and 100mN. The diffusion layer with thickness of 170 – 180 μm consists of a base with hardness of 8 – 9 GPa, containing mild etching inclusions of up to 5 μm with microhardness of 21 – 25 GPa. The base of the layer represents an α-solid solution of vanadium in iron, and inclusions are carbides of VC0.863 type. By atomic force microscopy it was established, that the surface relief is defined by single, relatively large carbide particles with a size of up to 3 μm, and by plural nano-sized carbide particles, which act as  the strengthening phase, providing high microhardness of the coating. By method of indentation of the hardened layer cross section using different loads hardening effect of the carbide particles is proven. Estimation of possible mechanisms of hardening have shown that the greatest contribution to diffusion layer hardening is made by dispersion component significantly increasing the yield stress of α-solid solution of iron in comparison with the initial state, which is 38 times greater than the contribution of solid-solution hardening.

scholarly journals Microstructure and mechanical properties of high-manganese-containing high-speed twin-roll cast Al-Mn-Si alloy strips and their cold-rolled sheets

2020 ◽  
Vol 326 ◽  
pp. 06004
Author(s):  
T.Ha Nguyen ◽  
Ram Song ◽  
Yohei Harada ◽  
Shinji Muraishi ◽  
Shinji Kumai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
High Speed ◽  
Solid Solution Hardening ◽  
Columnar Dendrite ◽  
Dispersion Hardening ◽  
High Manganese ◽  
Solution Hardening ◽  
Cold Rolled ◽  
Twin Roll

Al-Mn based alloys with high-manganese content are expected to have improved mechanical properties due to solid solution hardening and/or dispersion hardening. However, the increase of Mn solubility of the alloy is difficult by using the conventional DC casting. In order to solve this problem, in the present study, we focused on the twin-roll casting method which is characterized by high cooling rates. Several kinds of high Mn-containing Al-Mn-Si alloy strips were fabricated by using a vertical-type high-speed twin-roll caster equipped with a pair of water-cooled copper rolls. Direct temperature measurement of the liquid melt during the casting was also performed. The alloy strips of various compositions containing up to 4 Mn and 2 Si (wt%) were successfully obtained. By observing the microstructure of the cross section of the strip, we found the characteristic solidified structure. The solidified structure consisted of three layers. Two solidified shells with a columnar dendrite structure grew from the roll surfaces toward the strip center. In the mid-thickness region, the band structure consisting of equiaxed dendrites and globular grains was observed between the solidified shells. Very fine primary particles were observed in the matrix near the strip surface, while, relatively coarse particles with blocky and needle-like shape were observed in the central band of the as-cast strip. The electric conductivity measurement was performed for the as-cast strips. Mn solubility in Al matrix was estimated from the obtained values. The estimated Mn solubility in the Al-2Mn-xSi strips was between 1.5 ~ 1.8wt% Mn. It was over 1.43wt%Mn for the Al-4Mn-xSi strips. We found that the Mn solubility of the as-cast strips was considerably high. The strips were cold-rolled to the sheets and then annealed at various conditions. They were subjected to the tensile tests, and the effects of solid solution hardening and dispersion hardening are discussed.

Preparation, Structure and Mechanical Properties of RuAl and (Ru,Ni)Al Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
A. L. R. Sabariz ◽  
G. Taylor
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Room Temperature ◽  
Binary Compound ◽  
Lattice Parameter ◽  
Al Alloys ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Cscl Type ◽  
The Difference

ABSTRACTThe intermetallic compound, RuAl with B2 CsCl type structure, has been shown to possess room-temperature toughness and plasticity. NiAl also forms a B2 compound and it is claimed that a pseudo-binary compound, (Ru,Ni)Al, may be formed because the difference in lattice parameter between the two binary phases is slight. In this work a study has been made of the mechanical properties of some polycrystalline compounds, across the RuAl-(Ru,Ni)Al pseudo-binary, prepared from high-purity elemental powders. Compressive yield stresses were measured between room-temperature and 900°C, and the mechanisms of plastic flow are discussed in relation to the dislocation structures observed by TEM. Hot-microhardness tests were made to provide an indication of the effect of solid-solution hardening.

Microstructure and Mechanical Properties of Rapidly Solidified Al-Fe-Ni-Mg Alloys

2011 ◽  
Vol 674 ◽  
pp. 165-170 ◽  
Author(s):  
Anna Kula ◽  
Ludwik Blaz ◽  
Makoto Sugamata
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Rapid Solidification ◽  
Spray Deposition ◽  
Research Work ◽  
Mg Alloys ◽  
Solid Solution Hardening ◽  
Compression Tests ◽  
Microstructure And Mechanical Properties ◽  
Wide Range

Rapid solidification (RS) combined with following mechanical consolidation of RS powders is considered as a valuable commercial method for the production of a wide range of metallic materials having fine-grained structures. Reported research results for various alloys demonstrate better compositional homogeneity, smaller grain size and relatively fine precipitates distributed homogenously in RS alloys than that for the materials produced by conventional metallurgical processing. The effect of rapid solidification on the microstructure and mechanical properties of selected Al-Fe-Ni-Mg alloys have been investigated. The basic item of the research work was obtaining aluminum PM materials strengthened by highly-dispersed transition metal compounds and aluminum-magnesium solid solution. Rapid solidification (RS) of Al-4Fe-4Ni and Al-4Fe-4Ni-5Mg alloys was performed by means of gas atomizing of the molten alloy and the spray deposition on the rotating water-cooled copper roll. Using typical powder metallurgy (PM) methods, i.e. cold pressing, vacuum degassing and hot extrusion, the RS-flakes were consolidated to the bulk PMmaterials. For comparison purposes, the conventionally cast and hot extruded Al-4Fe-4Ni and Al-4Fe-4Ni-5Mg alloys were studied as well. Mechanical properties of as-extruded materials were examined by compression tests performed at 293 K – 873 K. It was found that relatively high strength of as-extruded PM materials was accompanied by high ductility of samples deformed by hot compression test. Structural observations confirmed beneficial influence of rapid solidification on effective refining of intermetallic compounds, although some inhomogeneity of fine precipitates distribution was observed. Nevertheless, it was considered that an effective increase of the microhardness and strength of tested RS materials mostly result from achieved dispersion of structural components and can be intensified by solid solution hardening due to Mg-addition.

scholarly journals Microstructure and mechanical behavior of Al-xMg/5Al2O3 nanostructured composites

2022 ◽  
Author(s):  
Mehdi Delshad Chermahini ◽  
Ghorbanali Rafiei Chermahini ◽  
Jamal Safari
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Milling Time ◽  
High Energy ◽  
Milling Process ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Nanostructured Composite ◽  
Powder Particles ◽  
Mg Content

Abstract The effect of Mg content and milling time were investigated on the microstructure and microhardness values of Al-xMg/5Al2O3 (x = 0, 4, 8 and 12 wt %) nanostructured composite prepared via high energy milling technique. XRD results showed an acceleration of alloying process and formation of Al (Mg) ss by enhancing percentage of Mg element. Also, by increase in Mg percentage the grain size reduction was more considerable during milling treatment. Additionally, increment of the Mg content up to 12 wt%, causes the increase in micro-strain of the samples (from 0.31 to 0.82%). Increase in Mg concentration accelerates the mechanical milling process. According to SEM results a coaxial and circular morphology with a uniform distribution of powder particles has been formed. Up to 12 wt% (for each milling time), significant increase in microhardness (215 HV) was carried out due to solid solution hardening and crystallite refinement. From 10 to 15 h, a slight increase in microhardness up to 218 HV can be observed.

Effect of Reaction between Fe and Carbide Particles on Mechanical Properties of Fe-Base Composite

2008 ◽  
Vol 55-57 ◽  
pp. 357-360 ◽  
Author(s):  
S. Chakthin ◽  
Nuchthana Poolthong ◽  
Ruangdaj Tongsri
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Carbide Particle ◽  
Sintering Temperature ◽  
Particle Sizes ◽  
Different Temperatures ◽  
Base Composite ◽  
Sic Composites ◽  
Carbide Particles ◽  
Sic Particle

Sintered Fe-5 wt. % carbide (SiC or TiC) composites have been prepared via a powder metallurgy (P/M) route. Two carbide particle sizes, < 20 µm and 20-32 µm, were mixed with Fe powder. The powder mixtures were compacted and sintered at 3 different temperatures, 1100, 1150 and 1200 °C. Microstructures of sintered Fe-5 wt. % SiC composites showed evidence of SiC decomposition. The decomposed Si and C atoms diffused into Fe particles resulting in formation of solid solution of Si and C in Fe during sintering. During cooling, the solid solution of C in Fe decomposed to pearlite structure (ferrite and cementite (Fe3C) lamellar structure). Microstructures of sintered Fe-5 wt. % TiC composites showed no evidence of TiC decomposition at the investigated sintering temperatures. Because of the reaction between SiC and Fe, tensile strength and hardness of the sintered Fe-SiC composites were higher than those of the sintered Fe. Experimental results showed that strength and hardness of the sintered Fe-SiC composites increased with increasing sintering temperature and with decreasing SiC particle size. In contrast, mechanical properties of the sintered Fe-TiC composites were inferior to those of the sintered Fe. The reason of poor mechanical properties may be attributed to poor bonding between Fe and TiC particles.

The Effect of Tungsten on the Mechanical Properties of Tantalum

1999 ◽  
Vol 121 (2) ◽  
pp. 172-177 ◽  
Author(s):  
C. L. Briant ◽  
D. H. Lassila
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Yield Strength ◽  
Mechanical Behavior ◽  
Work Hardening ◽  
Solid Solution Hardening ◽  
Solution Hardening

This paper reports a study of the mechanical behavior of Ta-W alloys. The results show that tungsten additions increase the yield strength and the rate of work hardening of tantalum. These additions also cause a change in the deformed microstructure from one that is primarily cellular to one that consists mostly of dislocation tangles. It is proposed that the increase in yield strength arises from solid solution hardening and that the increase in the work hardening can be correlated with an increase in the density and arrangement of dislocations present in the material.

Effects of Annealing Temperature and Si Content on Mechanical Properties of Cold Drawn Pearlitic Steel Wires

2007 ◽  
Vol 345-346 ◽  
pp. 65-68
Author(s):  
Dae Bum Park ◽  
Won Jong Nam
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Silicon Content ◽  
Annealing Temperature ◽  
Pearlitic Steel ◽  
Age Hardening ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Steel Wires ◽  
Si Content

The effects of annealing temperature and silicon content on mechanical properties on cold drawn pearlitic steel wires were investigated. Cold drawn steel wires, containing Si, 0.99 ~ 1.4%, were annealed at the temperature of 200 ~ 450°C with different annealing time. The variation of microstructural evolution with annealing temperature was not affected by silicon content. For steels containing high silicon content above 1.0%, the increase of silicon content did not cause the changes of peak temperature showing age hardening and age softening, except for the increase of tensile strength due to solid solution hardening.

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