How do deal with carbon steel castings when there are issues?

- Aug 15, 2017-

Carbon steel sand castings can be divided into hot cracks and cold cracks.The cast carbon steel sand casting is formed by the liquid steel shrink and deform at high temperature.The stress generated after cooling and shrinkage for carbon steel castings are blocked.When the stress exceeds the strength or plastic limit of the molten steel at the temperature,then generate cracks. The crack in carbon steel casting is caused by the following:

(1) sulfur, phosphorus and other harmful elements are high enough to form a hot crack;

(2) steel inclusions and segregation easily lead to stress concentration;

(3) the greater the line shrinkage of molten steel, the greater the tendency of hot cracking;

(4) carbon steel castings design structure is not easy to produce localized stress concentration, but also lead to thermal cracking;

(5) molten steel pouring temperature is high and easy to produce hot cracks;

(6) pouring cup and riser for carbon steel casting is improper position which result in contraction blocked and produce hot cracks;

(7) sand and plastic pestle is too tight,poor concession and hinder contraction that all increase the tendency of hot cracking;

(8) cooling rate of carbon steel sand casting is too fast or boxing is too early which will cause a greater premature cooling stress and increase the tendency of hot cracking;

(9) carbon steel castings cut gate cup, improper riser or improper cleaning.If cooling too fast or uneven after heat treatment will also lead to hot cracking;

(10) carbon steel castings cool to a lower temperature range,the cold crack is formed due to residual stress or external conditions of carbon steel casting.