Hot cracking
Hot cracking is a kind of hot cracking, which is characterized by crooked crack shape, irregular fracture surface, wide surface and narrower inside. The mechanism is as follows: the molten steel begins to condense after it is injected into the mold cavity. When the crystal framework has been formed and linear shrinkage begins, the shrinkage is blocked because the molten steel is not solidified into a solid state at this time, and the stress or plastic deformation will occur in the casting. When they exceed the material strength limit at this high temperature, the casting will crack.
Morphology and characteristics of hot cracks
Hot crack is a kind of crack which is caused by the blocked solid shrinkage of the casting when the strength and plasticity of the casting are very low at the end of solidification or shortly after solidification. Hot crack is one of the common casting defects in steel castings, malleable iron castings and some light alloy castings. The hot cracks initiate and propagate along the grain boundary, and their shape is uneven, tortuous and irregular. The surface of the crack is oxidation color, no metallic luster. The crack surface of steel casting is nearly black, while that of aluminum alloy is dark gray. The external crack can be seen by naked eye, and can be distinguished from cold crack according to the shape and fracture characteristics.
Hot crack can be divided into outer crack and inner crack. The hot crack that can be seen on the surface of casting is called external crack. The external cracks often occur at the corner of casting, the sharp change of section thickness, the slow solidification and the stress concentration. It is characterized by wide surface, narrow interior and tearing shape. Sometimes the fracture will run through the whole casting section. Another characteristic of hot crack is that the crack distributes along the grain boundary. The internal crack usually occurs in the final solidification part of the casting. The shape of the crack is very irregular, and the cross section is often accompanied by dendrites. Generally, the internal crack does not extend to the surface of the casting.
ABOUT KEVA
Keva Casting is a professional casting company that focuses on Construction, Machinery, Automobile, Hardware, Pipeline and many other industries.
We provide top quality products with the best service based on our complete production chain including our own mold design, advanced production techniques, and full management of the supply chain. Keva Casting has two factories located in Zhucheng, China's Shandong province.
We use "shell molding", which is a new technique that has been developed in recent years.This new technique has simplified production procedures and reduced air pollution compared with traditional sand casting and investment casting. Shell making and core making are faster to ensure production in enormous quantities. The dimensions and surface finishing are satisfactory for all kinds of industrial requirements. Besides supplying our own formwork & scaffolding systems, our casting products also supply OEM services in various industries.