This is just an experience data. Perpendicular to basal plane. The thermal conductivity results of the gray iron samples decrease with increasing temperatures, and are almost constant for the CGI samples. Class 20 has a high carbon equivalent and a ferrite matrix. Normally, the production does not need heat treatment. The numbers are the average of 2 measurements. In China, most of iron foundries can produce this grade iron castings.
The silicon promotes good corrosion resistance and increased fluidity when casting. According to the related standards, the mechanical properties are the inspection standard. Comparing with the results on Table 2, the effect of temperature, reducing the thermal conductivity of gray irons, is much higher in the results we obtained figure 6. Abstract It is presented an experimental study about thermal conductivity in gray iron and compacted graphite iron. A moderate cooling rate forms a more pearlitic matrix, while a fast cooling rate forms a more ferritic matrix. The casting shall be subjected to a tension test to determine its tensile strength. From Wikipedia, the free encyclopedia. Another factor affecting graphitization is the solidification rate; the slower the rate, the greater the time for the carbon to diffuse and accumulate into graphite.
The investigated specimen is put in a stack in tight thermal contact with two reference materials of the same diameter.
Radial heat losses are minimized by a guard heater and other experimental setup.
Database of Steel and Alloy (Marochnik)
The minimum tensile strength of propertiez is Mpa, it’s elongation is larger than 5. A moderate cooling rate forms a more pearlitic matrix, while a fast cooling rate forms a more ferritic matrix.
The tests were conducted up to C. The elongation is only for reference. It is observed that gray iron poperties discs are better heat conductors than CGI, causing the CGI casting to reach higher temperatures in service. The results show that gray iron presents always higher thermal conductivity than CGI. Separately cast test bars having the required dimensions shall be poured from the same lot as the castings represented. Grey Cast Iron Composition: These grades are a measure of the tensile strength-to- Brinell hardness ratio.
One possible reason for that is that the carbon content from our samples 3,5 is higher than the usual carbon contents of gray iron 3,4resulting in higher amount of graphite lamellar. Microstructure and mechanical properties of the CGI samples.
Gray Iron ASTM A48 Class 30 Data Sheet | Penticton Foundry
Enter your search terms Submit search form. In a general way the alloying elements tend to decrease thermal conductivity, so those alloyed gray irons must present thermal conductivity values lower than the regular gray irons. ASTM A – 04 Standard Specification propefties Gray Iron Castings for Valves, Flanges, and Pipe Fittings This guide prpperties standard specification for three classes of gray iron for castings intended for use as valve pressure retaining parts, pipe fittings, and flanges.
The results show the potential of irom CGI for applications like engine cylinder heads. It is used for housings where the stiffness of the component is more important than its tensile strength, such as internal combustion engine cylinder blockspump housings, valve bodies, electrical boxes, and decorative castings.
Gray iron above class 40 requires alloying to provide solid solution strengtheningand heat treating is used to modify the matrix.
This trend is observed in many reports [ 131012 ], although there is no discussion on the cause of this behavior. The surface of the casting shall be free of adhering sand, scale, cracks, and hot tears, as determined by visual examination.
Another feature of jron ductile cast iron is its good machinability, which is higher than for the steel and the common cast iron at the same prperties level one. The thermal conductivity of graphite parallel to basal plane. It represents the completion of the studies carried out to find casting and treatment methods which could modify the graphite, turning the flake form into a nodular or a spheroid one, not to stop the continuity of the cast iron matrix, and thus getting rid of the first cause of the cast iron shortness.
Gray iron also experiences less solidification shrinkage than other cast irons that do not form a graphite microstructure. Normally, the production does not need heat treatment. Castings shall be stress-relieved by placing them in a suitable furnace and heating them uniformly to the temperatures and for the times specified.
In two dimensions, as a polished surface, the graphite flakes appear as fine lines. It is named after the gray color of the fracture it forms, which is due to the presence of graphite. In this case, the larger amount of ferrite in the CGI Grade resulted in increasing thermal conductivity.
Higher strength gray irons, up to class 40, have lower carbon equivalents and a pearlite matrix. Those are standards samples for tensile tests.
Tension test specimens shall have threaded ends and irn conform to the prescribed dimensions. The test bars shall be cast in dried siliceous sand molds maintained at approximately room temperature.
Results of thermal conductivity for ductile irons [ 3 ]. A typical chemical composition to obtain a graphitic microstructure is 2. Typical values of thermal conductivity of different gray and ductile irons grades can be seen in tables 2 and 3 for increasing temperatures. Reference material is electrolytic iron with certified thermal conductivity. It is shown that, in CGI high nodularity decreases thermal conductivity, while iroon temperatures have little effect in this property.
Thermal conductivity, cast irons, compacted graphite iron, gray iron, cylinder heads. From Wikipedia, the free encyclopedia.
EN-GJL, Grey Cast Iron GG20
Effect of graphite amount on the thermal conductivity, for gray iron O and ductile iron Dwith ferritic matrix [ 9 ]. Cast iron Ferrous alloys Iron.
Gray iron samples were obtained from bars with 30 mm diameter, and CGI samples were machined from keel blocks of 25 mm, casted in chemically bonded sand moulds. Class 20 has a high carbon equivalent and a ferrite matrix.