所属分类：常见问题 发布时间：2021-02-19 11:47:07 来源：http://www.lcnmb500.com 浏览量：
Hardox450 wear resistant plate factory crack prevention measures. When the internal stress exceeds the tensile strength of the metal material, the casting will produce cracks. According to the temperature of the casting, the cracks can be divided into hot crack and cold crack.
① Hot cracking. The strength of the metal at high temperature is very low. If the linear shrinkage of the metal is hindered by the mold or core, and the mechanical stress exceeds the strength of the metal at this temperature, hot cracking will occur.
Hot crack characteristics of wear-resistant plate: the size of hot crack is short, the gap is wide, the shape is zigzag, and serious oxidation color appears in the gap. The main influencing factors of hot cracking are alloy properties (crystallization characteristics and chemical composition) and mold resistance (concession of mold and core).
Methods to prevent hot cracking in hardox450 wear resistant plate factory: reasonable casting structure; good concession of molding sand and core sand; strict limitation of sulfur content in steel and cast iron (especially the latter, because sulfur can increase the hot brittleness of steel and cast iron and reduce the high temperature strength of alloy), etc.
② Characteristics of cold cracks in wear-resistant plate: smooth surface, metallic luster or micro oxidation color, running through the whole grain, usually in smooth curve or straight line. The alloys with high brittleness and poor plasticity, such as white cast iron, high carbon steel and some steels, are easy to produce cold cracks, and large complex iron castings are also easy to produce cold cracks. Cold cracking often occurs in the part of casting under tensile stress, especially in the part of stress concentration.
The method to prevent cold cracking in hardox450 wear resistant plate factory is to reduce the internal stress of casting and the brittleness of alloy. For example, the wall thickness of castings should be uniform; the concession of molding sand and core sand should be increased; the phosphorus content in steel and cast iron should be reduced (because phosphorus can significantly reduce the impact toughness of alloy and make steel produce cold embrittlement). For example, when the phosphorus content of cast steel is more than 0.1% and that of cast iron is more than 05%, the cold cracking tendency increases obviously due to the sharp decrease of impact toughness).