Microstructure of steel in as-cast and heat treated conditions were studied using SEM and optical microscopy. Tensile specimens were machined to ASTM E8 size ‘3’ from the pre-cast tensile bars and Charpy bars were machined prior to aging to ASTM E23 using a dedicated mill for making Charpy bars. A servo-hydraulic test frame, equipped with la- ser extensometer was used to measure elongation and tensile properties. A displacement rate of 0.02mm/s was used dur- ing the tension test. Fracture surfaces of tensile specimens were observed using a field emission SEM.
Results Homogenization Treatment
The goal of homogenization is to remove alloy segregation as much as possible. In particular, Cr segregation will affect
Figure 4. No bake molds and shell molds after pouring.
(a)
(b)
Figure 5. Back scattered electron images (using ASPEX SEM) of as-cast CB7Cu-1 steel (a) base heat (b) heat 3. The Cr- rich phase was identified as ferrite.
Table 4. EDS Analysis Of Matrix And Interdendritic Regions Of The Base Heat And Heat
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International Journal of Metalcasting/Spring 10
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