scholarly journals Improvement of mechanical properties of iron castings via adjusting of solidification rate

2020 ◽  
pp. 17-20
Author(s):  
N. I. Gabelchenko ◽  
A. A. Belov ◽  
N. A. Kidalov ◽  
A. I. Gabelchenko
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Solidification Rate ◽  
Crystallization Rate ◽  
Heat Extraction ◽  
Eutectic Transformation ◽  
Primary Austenite ◽  
Iron Castings ◽  
Alloying Additives ◽  
Air Blowing

The work is devoted to improvement of mechanical properties of iron castings via adjusting of the cooling rate without introduction of alloying additives. The new technological solution is suggested; it can be easily adapted to a casting technology. This solution is based on variation of the cooling rate of iron castings within structurally sensitive solidification intervals. For this purpose, the casting mould was initially cooled after pouring, then heated and cooled again. Cooling of the mould during the period of primary austenite crystal forming led to increase of dendrite crystallization rate and was executed using compressed air. Retarding of the cooling rate during the period of eutectic transformation was provided by the mould heating via burning of exothermic carbon-containing additives introduced in a facing layer of sand-clay moulding mix. Burning reaction is accompanied by heat extraction, what steeply retarded the cooling rate within the interval of eutectic transformation. Consequent acceleration of castings cooling within the interval of eutectoid transformation was achieved via repeated air blowing through a worked reaction layer. Adjusted cooling of iron castings allowed to provide the most favourable solidification conditions, taking into account strictly individual requirements for each structurally sensitive temperature intervals. It led to increase of a volumetric part of primary austenite dendrite crystals, to decrease of eutectic transformation overcooling degree, to forming of graphite eutectics and enlargement of dispersity of pearlite component in iron. Consequently, lowering of widespread iron castings rejects takes place, among them chilling, with simultaneous improvement of metal mechanical properties. As a result, the primary and real structures were varied, what had a positive effect on mechanical properties of casting metal. It is shown that use of solidification rate adjustment led to essential increase of metal tensile strength for the experimental casting.

scholarly journals RESEARCH OF THE INFLUENCE OF SLOW-DOWN COOLING SPEED IN THE INTERVAL OF EUTEKTIC TRANSFORMATION ON THE STRUCTURE AND MECHANICAL PROPERTIES OF CAST IRON CASTINGS

2020 ◽  
pp. 51-55
Author(s):  
N. I. Gabelchenko ◽  
N. A. Kidalov ◽  
A. A. Belov ◽  
M. D. Bezmogorychnyy ◽  
A. I. Gabelchenko
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Cooling Rate ◽  
Quality Index ◽  
Fuel Oil ◽  
Controlled Cooling ◽  
Slowing Down ◽  
Eutectic Transformation ◽  
Iron Castings ◽  
Cooling Speed

The work is devoted to the study of the effect of slowing down the cooling rate in the interval of eutectic transformation on the structure and mechanical properties of castings from gray doeutectic iron. To slow down the cooling rate in the interval of eutectic transformation, an exothermic carbon-containing additive, fuel oil M-100, was used. It is shown that the use of controlled cooling can significantly increase the quality index of cast iron without introducing additional alloying elements into the composition of cast iron.

scholarly journals The Casting Rate Impact on the Microstructure in Al–Mg–Si Alloy with Silicon Excess and Small Zr, Sc Additives

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2056
Author(s):  
Evgenii Aryshenskii ◽  
Maksim Lapshov ◽  
Sergey Konovalov ◽  
Jurgen Hirsch ◽  
Vladimir Aryshenskii ◽  
...  
Keyword(s):  
Solid Solution ◽  
Cooling Rate ◽  
Supersaturated Solid Solution ◽  
Solidification Rate ◽  
Crystallization Rate ◽  
Alloying Elements ◽  
Grain Structure ◽  
Transmission Microscopy ◽  
Intermetallic Particles ◽  
Silicon Excess

The study investigates the effect of casting speed on the solidification microstructure of the aluminum alloy Al0.3Mg1Si with and without the additions of zirconium and scandium. Casting was carried out in steel, copper, and water-cooled chill molds with a crystallization rate of 20 °C/s, 10 °C/s, and 30 °C/s, respectively. For each casting mode, the grain structure was investigated by optical microscopy and the intermetallic particles were investigated by scanning and transmission microscopy; in addition, measurements of the microhardness and the electrical conductivity were carried out. An increase in the solidification rate promotes grain refinement in both alloys. At the same time, the ingot cooling rate differently affects the number of intermetallic particles. In an alloy without scandium–zirconium additives, an increase in the ingot cooling rate leads to a decrease in the number of dispersoids due to an increase in the solubility of the alloying elements in a supersaturated solid solution. With the addition of scandium and zirconium, the amount of dispersoids increases slightly. This is because increasing the solubility of the alloying elements in a supersaturated solid solution is leveled by a growth of the number of grain boundaries, promoting the formation of particles of the (AlSi)3ScZr type, including those of the L12 type. In addition, the increase in the crystallization rate increases the number of primary nonequilibrium intermetallic particles which have a eutectic nature.

scholarly journals Effect of Section Size as a Measure of Cooling Rate on the Solidified Microstructure and Mechanical Properties of Sand-Cast Al-Si Eutectic Alloy

2020 ◽  
Vol 18 ◽  
pp. 8-22
Author(s):  
Udochukwu Mark
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Eutectic Alloy ◽  
Pure Metal ◽  
Solidification Time ◽  
Heat Extraction ◽  
Spectrometric Analysis ◽  
Pure Aluminium ◽  
Sand Cast ◽  
Section Size

Several factors contribute to the development of structure and properties of aluminiumalloy castings. This study investigated the singular effect of cooling rate on the as-cast structure andmechanical properties of an aluminum-silicon eutectic alloy, keeping other factors such as pouringtemperature, melt treatments, physical and thermal properties of the mould, and alloy compositionconstant. The rate of cooling was varied by employing different casting section sizes, based on thevariation of rate of heat extraction given by solidification time as predicted by the Chvorinov’s rule.Four test bars of section sizes 10, 20, 30, and 40 mm respectively were cast in sand mould using thesame gating system. Spectrometric analysis of the alloy formulated revealed that it could be specifiedapproximately as Al-12.8Si-1.0Cu alloy. The study showed that as section size decreased from 40mm to 10 mm; the solidification time reduced (i.e. the cooling rate increased), the microstructure gotfiner, the silicon flakes became more uniformly distributed, and the mechanical properties generallyimproved. The tensile strength, ductility, and hardness all increased in the order of decreasing sectionsize, i.e. increasing cooling rate. The mechanical properties were found to be linearly correlated withsection size or cooling rate. Whereas the elongations were lower than values for pure aluminium, thestrength and hardness were significantly higher than values for the pure metal. It is concluded thatthe cooling rate modifies the microstructure and improves the mechanical properties of as-cast Al–Sieutectic alloys

Effect of Cooling Rate on the Microstructures and Mechanical Properties of Mg-Y Alloys

2014 ◽  
Vol 597 ◽  
pp. 135-139 ◽  
Author(s):  
Goh Chwee Sim ◽  
Khin Sandar Tun ◽  
Xing He Tan ◽  
Chan Kwok Jimmy Weng ◽  
Kwok Wai Richard Onn ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Solidification Rate ◽  
Air Cooling ◽  
Copper Mold ◽  
Metal Solidification ◽  
Steel Mold ◽  
Weight Percentage ◽  
Mold Casting ◽  
Gravity Cast

Magnesium (Mg) alloys with 30 weight percentage (wt.%) of yttrium (Y) were gravity cast using copper mold and copper mold with air cooling. The results were benchmarked with Mg-30Y alloys produced using steel mold casting. It was found that the Mg-30Y alloys cast using the copper mold with air cooling exhibited the best mechanical properties, whereby the compression strength and the Vickers hardness value peak at 633 MPa and 137.6 HV respectively. Microstructural observations show that with increasing cooling rate, and hence increasing molten metal solidification rate, the dendrite structures are much finer due to enhanced nucleation rate. This is due to limited time for the dendrites to coarsen.

scholarly journals The Effect of Solidification Rate on the Microstructure and Mechanical Properties of Pure Magnesium

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1264
Author(s):  
Murtatha M. Jamel ◽  
Hugo Lopez ◽  
Benjamin Schultz ◽  
Wilkistar Otieno
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Fracture Behavior ◽  
Solidification Rate ◽  
Casting Process ◽  
Grain Structure ◽  
Rockwell Hardness ◽  
Cooling Rates ◽  
Liquid Co2 ◽  
Processing Defects

Magnesium, Mg, has been widely investigated due to its promising potential as magnesium alloys for various applications, particularly as biomedical implantation devices among other medical applications. This work investigates the influence of different cooling rates on the strength of pure Mg. The cooling rates were set to cover a low cooling rate LCR (0.035 °C/s) in an insulated furnace, a moderate cooling rate MCR (0.074 °C/s) in uninsulated-ends furnace, and a high cooling rate HCR (13.5 °C/s) in liquid CO2. The casting process was accomplished using a closed system of melting and cooling due to the reactivity-flammability of magnesium in order to minimize processing defects and increase the safety factor. The as-cast samples were metallographically examined for their microstructure, and properties such as impact strength, hardness, and tension were determined. Increasing the solidification rate from 0.035 °C/s to 0.074 °C/s increased the hardness from 30 to 34 Rockwell Hardness and the UTS from 48 to 67 MPa. A higher solidification rate of 13.5 °C/s further enhanced the hardness to 48 Rockwell Hardness and the UTS to 87 MPa in comparison to the 0.074 °C/s cooling rate. Additionally, the fracture behavior and morphology were investigated. It was found that in general, the mechanical properties tended to improve by refining the grain structure.

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).

scholarly journals A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 776
Author(s):  
Sixiang Zhai ◽  
Qingying Liu ◽  
Yuelong Zhao ◽  
Hui Sun ◽  
Biao Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Composite Materials ◽  
Crystallization Rate ◽  
Research Progress ◽  
Poly Lactic Acid ◽  
Green Composite ◽  
Materials Development ◽  
Research Attention ◽  
Biomass Components

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

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