Lost wax casting stainless steel castings brittle fracture occurred for the following reasons:1, melting the deoxidizer aluminum consumption is too high, it with the nitrification in the steel is easy to form aluminum nitride clip and make the brittle fracture of the casting. 2, furnace lining building boric acid dosage is too high, and make the steel carbon boron compounds, namely "boron brittle". 3, excessive amounts of carbon and other alloying elements beyond the promise to scale will increase the brittleness of steel, such as in pig iron carburization, feeding carefully, or the accounting, will bring into harmful elements. 4, lost wax casting molten steel overheating and severe heat treatment operation wrong, coarse grains.