METHOD FOR OBTAINING VARIOUS METAL MATRIX STRUCTURES IN HIGH-STRENGTH SPHEROIDAL GRAPHITE CAST IRON SLABS FROM MOLTEN STATE

摘要

FIELD: metallurgy. SUBSTANCE: method involves producing high-strength spheroidal graphite cast iron slab by pouring melt into metal, sand or ceramic mold; withdrawing slab from mold at temperature of 900-1.000 C and quickly transferring into liquid bath with constant temperature of quenching medium. Quenching medium temperature is determined depending on required metal matrix structure of high-strength spheroidal graphite cast iron. Each metal matrix structure is characterized with specific temperature of quenching medium: ferrite structure 750-850 C; pearlite structure 650-740 C; sorbite structure 550-640 C; troostite structure 450-540 C; upper bainite structure 350-440 C; lower bainite structure 290-340 C. Isothermal holding of slab in liquid bath depends on completeness of structural transformation. Method further involves holding slab in bath for predetermined time, withdrawing and cooling it in air. Method allows slabs having required mechanical and operating characteristics to be produced immediately from liquid state without thermal treatment and alloying with special elements. EFFECT: reduced time for producing high-strength cast iron slabs with different metal matrix structures and decreased production costs. 1 ex