It is one of the hydraulic universal test machine,is designed for testing metals and other materials under tension, compression bending, transverse, brinelland shear loads.Equip with digital display,clear machine test process with test result shown,very easy to operate.
Attached with simple accessories and devices, it also can be used for test wood, concrete, cement, rubber, and many other non-metal materials.
In accordance with the ISO, ASTM, JIS, GB and most of all the different standards,advanced testing technology and high quality.
Digital Display Hydraulic Utm,Digital Bending Test Machine,Digital Display Compression Testing Machine,Digital Display Hydraulic Universal Testing Machine JINAN KASON TESTING EQUIPMENT CO., LTD. , http://www.hstester.com
Effect of Carbon Equivalent on Shrinkage Defects Under the premise of other chemical compositions, the shrinkage volume of carbon equivalent at 316 to 510 during wet casting was measured. For the test results. It can be seen that the higher the carbon equivalent, the smaller the shrinkage volume. Generally controlled at 414A6, the shrinkage volume is the smallest. If the carbon equivalent is too high, graphite will float.
Effect of Carbon Equivalent on Shrinkage Holes Carbon equivalent is not only an important factor affecting the width of the molten iron solidification temperature range, but also has an effect on the solidification process. During the cooling and solidification process of the molten iron, when the outer shell of the casting is formed, the outer shell undergoes solid shrinkage during the subsequent cooling process, while the inner paste region produces liquid shrinkage and solidification shrinkage. If the solid state shrinkage of the layer is smaller than the internal liquid shrinkage amount and the solidification shrinkage amount, and the filler passage is cut, and the molten iron is not replenished, shrinkage defects are generated.
Ductile iron precipitates graphite during solidification, accompanied by graphitization, especially eutectic graphitization, and its volume also expands. After the carbon equivalent of the original molten iron is increased, the graphitization of the solidification process is sufficiently performed to promote a large volume expansion, thereby reducing the volume of the shrinkage cavity.
The influence of the mold stiffness on the shrinkage cavities under different carbon equivalents of three different stiffnesses was used in the range of the test carbon equivalent. As shown, the curve A is wet, the compactness of the sand is lower, the surface hardness is 40; the curve B is dry, the compactness is higher, the surface hardness is 60; the curve C is the water glass quick-drying type, the surface The hardness is 80.
The test results show that the stiffness of the mold has a large influence on the volume of the shrinkage cavity. The higher the stiffness, the smaller the volume of the shrinkage cavity. Therefore, increasing the compactness of the cast sand and increasing the rigidity of the mold, thereby controlling the expansion of the outer shell during the solidification of the molten iron, is effective for reducing and preventing the occurrence of shrinkage cavities.
The effect of the cooling rate on the shrinkage cavity defects accelerates the cooling rate of the casting, prompting the casting layer to solidify faster and form a strong outer casing, so that the possibility of shrinkage of the casting is reduced. To this end, the effects of four cooling conditions on the shrinkage cavities were tested at different carbon equivalents. For the test results. A is cast after the mold is preheated to 400e; B is cast after the mold is preheated to 200e; C is the casting effect of the cooling speed of the mold at different carbon equivalents on the shrinkage hole at normal temperature; D is specially designed water. The cooled sand type, after pouring, is reinforced by water.
From A to D, the cooling rate increases in turn, while the shrinkage volume decreases in turn. After the cooling is accelerated, the solidification of the casting surface is accelerated, so that it forms a strong outer shell faster. When the internal molten iron solidifies, the volume expansion caused by graphitization is mainly used to offset the liquid shrinkage and solidification shrinkage, and is not enough to push the outer casing to move outward, thereby reducing the shrinkage volume.