PREVENTION OF METALLIZED BURN-ON ON STEEL CASTINGS.

Two conditions must be satisfied in order to prevent metallized burn-on, viz. , p//m less than p//c//r (where p//m is the hydrostatic metal pressure and p//c//r the critical sand counterpressure), and T//s less than T//c//r (where T//s is the surface temperature of the solidifying casting and T//c//r the critical temperature at which metal starts to penetrate pores in the mold wall and form burn-on). Since the first condition for burn-on prevention has been widely investigated, experimental data on the second condition are reported in this article. The influence of the liquidus-solidus interval on burn-on prevention was investigated at hot spots in the castings. Surface temperatures were measured during the solidification period, and compared with the computed cooling curves plotted by a procedure described previously.