Influences of Silicon and Phosphorus Contents and Cooling Rate on JIC Fracture Toughness of Ferritic Spheroidal Graphite Cast Iron

Abstract

The influences of silicon and phosphorus contents and cooling rate on JIC fracture toughness of ferritic spheroidal graphite cast iron were investigated by 15mm thick compact tension test-pieces. The JIC values were measured by means of the R-curve method for most cases at 20°C, and by means of the maximum J value method for the cases at -100° C. The results obtained are summarized as follows. At 20WC, the specimens with silicon contents less than 3.2% showed the ductile Load-COD relations, but a specimen with 3.5%Si showed a brittle Load-COD relation and the JIC decreased greatly. Increasing phosphorus content between 0.006% and 0.26% made the JIC value decrease gradually and made the slope of the R-curve decrease greatly. Difference in cooling rate produced differences in graphite nodule diameters and ferrite grain sizes. At 20°C, the larger the specimen's average graphite nodule diameter was, the larger the JIC value was. At -100° C, the Jic values of all the specimens tested decreased largely, and the influences of these factors became very different from those at 20° C.

Relaciones entre la microestructura y las propiedades mecánicas en fundiciones nodulares: revisión bibliográfica

“…El efecto de los elementos aleantes sobre las propiedades mecáni-cas también ha recibido atención, habiendo sido particularmente estudiado en fundiciones nodulares ADI, el efecto del silicio en la resistencia a la tracción e impacto . En fundiciones nodulares ferríticas se ha estudiado el efecto del silicio en la resistencia a la tracción, impacto y fractotenacidad [22] .…”