A steel mill specializing in manufacturing castings for customers* in the chemical industry has run into a problem when casting pump bodies and back covers using the 07ХН25МДТЛ steel. The castings failed tightness tests.
NPP Technology engineers have analyzed the test failures and recommended for use a multi-component inoculant, INSTEEL® 7. This inoculant contains titanium. It is a strengthening component, which, upon entry into the melt, promotes formation of carbonitrites. They, in their turn, tend to increase the wear resistance of parts. The REMs contained in the inoculant promote both the micro- and macrostructural refinement of steel and toughen castings across their entire sections. The inoculant also contains calcium that makes it possible for non-metallic inclusions with sharp edges and corners to be removed from the melt, and for sulfur to precipitate in rounded inclusions. These inclusions can be subsequently easily removed from the melt. Being efficient desulfurizer calcium promotes formation of globulized sulfides that float off in the slag. The barium contained in the inoculant increases and accelerates the efficiency of the calcium.
The use of INSTEEL® 7 has made it possible for the customer to bring down the failure rate from 70 % to 7 %. This inoculant has been commercially produced since 2016 and has been consistently improving the quality of castings.
*The name of the customer is withheld because it is classified information for OOO NPP Technology.