Nodulizer manufacturer—Lishi Industrial reminds you that the so-called pre-stove inspection is an indispensable link in the production process, and it is directly related to the quality of nodular cast iron. Timely and accurate judgment of the spheroidization of ductile iron can quickly take measures to control the quality of ductile iron. If the judgment is wrong before the heating furnace, a large number of castings will be scrapped and the molding time will be wasted. Therefore, the timely and accurate judgment of spheroidization before the furnace is more important than the detection after the furnace. In actual production, there are several methods for testing the spheroidization of molten iron in front of the furnace.
1. Surface crust and flame judgment method. Rare Earth Magnesium Ductile Iron has low content of magnesium and rare earth elements. The surface of liquid iron is not the same as that of pure magnesium ductile iron. There is not as much scale on the surface, and the flames are not as numerous and powerful. But when a third of the iron is added, the liquid level glows with magnesium and a white flame in the shape of a candle flame. According to the number and height of the fire to judge the nodularization and the residual amount of magnesium. The taller and more intense the flame, the better the nodularization. Especially when pouring, if the height is 50mm, the spheroidization is good; if the flame is less than 15mm, the spheroidization is poor. The surface of the treated nodular cast iron forms an oxide film, and silver-white rolling light spots appear, that is, the spheroidization is good. However, if the oxide film is too thick, the temperature of the molten iron will be low.
2. Triangular test block method. At present, judging spherification by observing the sample block is a common method. The panels used at each plant come in a variety of shapes and sizes, with most plants using triangular panels. According to the production characteristics of our factory, the size and thickness of the casting, the cross-sectional area of the triangular test block is selected to be 12.5mm (bottom) × 50mm (height). There are also some factories that use round samples, such as 15 mm, 25 mm, and 30 mm. After the iron solution is completed, use a sampling spoon to pour the liquid into the test block from 200mm below the surface of the iron solution, cool it to dark red, and quench it in water. The outer circle of the cylinder block is much larger than that of gray cast iron, and the appearance is clean and bright. It is usually a triangular test block cast in situ, and there are shrinkage cavities on both sides of the top surface of the horizontal casting block or shrinkage cavities on both sides. It is silver or silver white porcelain with sharp cracks and clear osteoporotic fractures. The radial pattern is silver with a high amount of surface agent added. It is more fashionable to make specimens at this time. The embrittlement of the faucet and the new If the mouth is made of silver, and there are evenly distributed small black spots, if the colored crystal is broken, it indicates that the spheroidization has failed.
To sum up, the pre-furnace inspection methods of nodulizer manufacturers are the above two methods, the surface crust and flame judgment method and the triangular test block method. These two methods have their own advantages and also have their own defects. Use it after detailed analysis.