scholarly journals The Influence of Undercooling DT on the Structure and Tensile Strength of Grey Cast Iron

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6682
Author(s):  
Józef Dorula ◽  
Dariusz Kopyciński ◽  
Edward Guzik ◽  
Andrzej Szczęsny ◽  
Daniel Gurgul
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Great Influence ◽  
Small Mass ◽  
Grey Cast Iron ◽  
Primary Austenite ◽  
Grey Cast ◽  
Austenite Grains ◽  
Mutual Relations

Inoculation of cast iron has become a commonly used metallurgical process, which is carried out in a foundry in order to improve the mechanical properties of utility alloys. It consists in changing the physicochemical state of the melted alloy. This change is caused by the introduction of cast iron with a low ability to nucleate graphite, shortly before pouring a small mass of the substance—an inoculant that increases the number of active nuclei. It is also justified that the literature often connects an increase in the tensile strength UTS of the inoculated grey cast iron, with changes in the characteristics of the particles of graphite. However, in strongly hypoeutectic cast iron, in which a large number of primary austenite grains crystallize, the interdendritic distribution of graphite is usually the result. It also follows that the nature of the graphite precipitates is determined by the mutual relations between the interfacial distances in eutectic grains and the interdendritic distances in the grains of primary austenite occurring in the Fe–C alloys. The article presents the influence of the inoculant on the characteristics of the precipitation of primary austenite grains in relation to the sulphur content in grey cast iron with flake graphite. The study also showed that primary grains in grey cast iron have a great influence on mechanical properties, such as the tensile strength UTS. In this case, the key is to know the value of the degree of undercooling DT. The type of inoculant used affects the DT value. The study related the number of N primary austenite grains with the degree of undercooling DT and the tensile strength UTS with the number of primary austenite N grains.

Cast Iron Solidification Structure and how it is Related to Defect Formation

2014 ◽  
Vol 790-791 ◽  
pp. 441-446 ◽  
Author(s):  
Lennart Elmquist ◽  
Kaisu Soivio ◽  
Attila Diószegi
Keyword(s):  
Cast Iron ◽  
Defect Formation ◽  
Hot Spot ◽  
Shrinkage Porosity ◽  
Grey Cast Iron ◽  
Solidification Structure ◽  
Eutectic Solidification ◽  
Primary Austenite ◽  
Grey Cast ◽  
Austenite Grains

In this work, the meaning of the solidification structure and how it is related to defect formation in grey cast iron will be discussed. The work also confirms observations made earlier. In previous work the formation of shrinkage porosity in grey cast iron cylinder heads was investigated. It was found that the defect is located around solidification units resembling primary austenite grains. The solidification of grey cast iron starts with the formation of primary austenite grains, followed by the eutectic solidification. The primary grains nucleate and grow either as columnar or equiaxed grains, creating a columnar to equiaxed transition between the two zones. Based on the presence of a migrating hot spot, and other characteristics found on the cylinder heads, a geometry was developed that promote the formation of shrinkage porosity. The primary solidification structure, normally transformed during the solid state transformation, was preserved using a technique called Direct Austempering After Solidification (DAAS). After solidification, the samples were cut and prepared for investigation using a Scanning Electron Microscope (SEM) equipped with a detector for Electron Back Scattered Diffraction (EBSD). Individual grains were identified and the primary solidification structure around the defects was revealed. The investigation shows how shrinkage porosity is formed and located between primary austenite grains. This confirms that the primary solidification structure has a large influence on the formation of defects in grey cast iron. The investigation also confirms the correctness of earlier results as well as the validity of the DAAS technique.

scholarly journals Inoculation of Austenite Primary Grains in Cast Iron

2014 ◽  
Vol 14 (4) ◽  
pp. 45-48 ◽  
Author(s):  
D. Kopyciński ◽  
E. Guzik ◽  
A. Szczęsny ◽  
J. Dorula ◽  
D. Siekaniec ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Iron Powder ◽  
Strength Properties ◽  
Flake Graphite ◽  
Primary Austenite ◽  
Commercial Inoculant ◽  
Austenite Grains ◽  
The Impact

Abstract The modification is a widespread method of improving the strength properties of cast iron. The impact in terms of increasing amounts of eutectic grains has been thoroughly studied while the issue of the impact on the mechanical properties of primary austenite grains has not been studied in depth yet. The paper presents the study of both aspects. The methodology was to conduct the melting cast iron with flake graphite, then modifying the alloy by two sets of modifiers: the commercial modifier, and a mixture of iron powder with a commercial inoculant. The DAAS test was carried out to identify the primary austenite grains. The degree of supercooling was determined and the UTS test was performed as well. Additionally carried out the metallographic specimen allowing for counting grains. It can be concluded that the introduction of the iron powder significantly improved the number of austenite primary grains which resulted in an increase in tensile strength UTS.

scholarly journals The Effects of Austempered and Quenched & Tempered on Mechanical Properties of Alloyed Grey Cast Iron

2018 ◽  
Vol 7 (4.12) ◽  
pp. 376
Author(s):  
Bulan Abdullah ◽  
Khalissah Yusof ◽  
Farahn Zamri, Nor ◽  
Hayati Saad
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cast Iron ◽  
Room Temperature ◽  
Salt Bath ◽  
Optical Microscope ◽  
Grey Cast Iron ◽  
Engine Oil ◽  
Heat Treated ◽  
Grey Cast

In this study, the effects of austempered and quenched & tempered on mechanical properties of grey cast iron with and without the addition of niobium were investigated. The austempering heat treatment started by heating the samples to an austenitizing temperature of 900°C with a soaking time of 90 minutes before quenched in salt bath furnace with a temperature of 360°C and hold for 180 minutes before it been cooled down to room temperature. The quench and tempering process started with heating the samples at 910°C and hold for 33 minutes. Then the samples are quenched by using engine oil before being heated up again to temperature of 400°C with soak time up to 17 minutes before allow it to be cooled at room temperature. The tests conducted include hardness, tensile and impact test. The microstructure of the samples was observed using optical microscope. The fracture surface of the test tensile and impact specimens was analyzed by using S.E.M. observation. The hardness of the as-cast, austempered and quenched & tempered alloyed grey cast iron are higher compared to the hardness of pure grey cast iron. By addition of Niobium, the tensile strength of the grey cast iron increased by 67.49 % compared to pure grey iron. Tensile strength and elongation of the alloyed grey cast iron slightly increased after heat treated. Austempered alloyed grey cast iron resulted the highest value of impact toughness (6.5 J) compared to other specimens. This showed that austempered alloy grey cast iron is the best in absorbing the energy subjected to it.  

scholarly journals Microstructure evolution and mechanical properties of drop-tube processed, rapidly solidified grey cast iron

2016 ◽  
Vol 654 ◽  
pp. 143-150 ◽  
Author(s):  
Olamilekan Oloyede ◽  
Timothy D. Bigg ◽  
Robert F. Cochrane ◽  
Andrew M. Mullis
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Microstructure Evolution ◽  
Grey Cast Iron ◽  
Drop Tube ◽  
Grey Cast ◽  
Rapidly Solidified

scholarly journals A rapid approach to estimate the mechanical properties of grey cast iron castings

2018 ◽  
Vol 24 (3) ◽  
pp. 213 ◽  
Author(s):  
Paolo Ferro ◽  
Thomas Borsato ◽  
Franco Bonollo ◽  
Stefano Padovan
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Master Curve ◽  
Mechanical Characterization ◽  
Grey Cast Iron ◽  
Iron Castings ◽  
Solidification Kinetics ◽  
Grey Cast ◽  
Microstructure Morphology

<p>Grey cast iron is a brittle or quasi-brittle material very sensitive to the microstructure morphology deriving from its solidification kinetics. This is the reason why different zones of a casting, even with the same thickness, may be characterized by different mechanical properties according to the solidification time. The mechanical characterization of the alloy made by following the Standards that refer to values obtained from separately casted samples is insufficient for a designer who needs to know the specific properties of the material in each zone of interest of the casting. In this work a method is described to predict the mechanical properties of castings made of GH 190 cast iron that correlates the solidification times with the ultimate tensile strength through a master curve, supposed to depend only on alloy chemical composition. This predictive approach was successfully validated with experimental mechanical characterization of a real industrial casting.</p>

scholarly journals Comparative Experimental Study of Tribo-Mechanical Performance of Low-Temperature PVD Based TiN Coated PRCL Systems for Diesel Engine

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Ghulam Moeen Uddin ◽  
Muhammad Sajid Kamran ◽  
Jawad Ahmad ◽  
Muhammad Ghufran ◽  
Muhammad Asim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Low Temperature ◽  
Cylinder Liner ◽  
Ceramic Coatings ◽  
Grey Cast Iron ◽  
Tin Coating ◽  
Ic Engine ◽  
Trade Offs ◽  
Grey Cast

Piston ring and cylinder liner (PRCL) interface is a major contributor to the overall frictional and wear losses in an IC engine. Physical vapor deposition (PVD) based ceramic coatings on liners and rings are being investigated to address these issues. High temperature requirements for applications of conventional coating systems compromise the mechanical properties of the substrate materials. In the current study, experimental investigation of tribo-mechanical properties is conducted for various titanium nitride (TiN) coated PRCL interfaces in comparison with a commercial PRCL system. Low-temperature PVD based TiN coating is successfully achieved on the grey cast iron cylinder liner samples. Surface roughness of the grey cast iron cylinder liner substrates and the thickness of TiN coating are varied. A comprehensive comparative analysis of various PRCL interfaces is presented and all the trade-offs between various mechanical and tribological performance parameters are summarized. Coating thickness between 5 and 6 micrometres reports best tribo-mechanical behaviour. Adhesion and hardness are found to be superior for the TiN coatings deposited on cylinder liner samples with higher roughness, i.e., ~ 5-micron Ra. Maximum 62 % savings on the COF is reported for a particular PRCL system. Maximum 97% saving in cylinder liner wear rate is reported for another PRCL system.

Inoculation of primary austenite in grey cast iron

2007 ◽  
Vol 20 (2) ◽  
pp. 68-72 ◽  
Author(s):  
A. Diószegi ◽  
K. Z. Liu ◽  
I. L. Svensson
Keyword(s):  
Cast Iron ◽  
Grey Cast Iron ◽  
Primary Austenite ◽  
Grey Cast
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