The invention relates to a
martensitic stainless steel pump case product for manufacturing a spray pump of a containment for a
nuclear power plant. High purity
molten steel with low gas content and uniform components is obtained by
intermediate frequency furnace and VOD duplexing
smelting; process parameters are obtained by
system design of industrial analysis,
chromite sands are used in a pump case runner, and the outer layer of the
chromite sands is cast by
furan resin sands to ensure that the runner is smooth and level; the accuracy of a core
assembly and a lower core is ensured by using a snap-gauge, so that the dimensional tolerance of the runner satisfies the requirement;
thermal treatment process parameters are adjusted through a process test, in-
furnace temperature, temperature raising rate, insulating temperature,
quenching temperature and
quenching transfer time are controlled, and the problems of low
impact performance and high
hardness are solved through
tempering twice. The problem that previous cast product is more in
porosity defect, severe in surface sand burning, poor in
dimensional precision of the runner and relatively poor in
mechanical property is solved, and the
corrosion-resistant
martensitic stainless steel pump case cast which is high in
dimensional precision, few in technical defect, compact in internal tissue and free of sand burning in the cavity of the runner is obtained.