Pearlitic-malleable-iron castings

Pearlitic-malleable-iron castings are used where high strength is required together with a good wear-resistance. There are many applications. 

Style AA cast elevator buckets, which have generally replaced style A in popularity, are designed similar to style A except that a heavy reinforcing band is cast along the front. Style AA buckets are furnished in either malleable or pearlitic malleable iron. 

Style AA-RB cast elevator buckets are used for handling heavy abrasive products under severe service and impact conditions. Buckets are designed similar to style AA with reinforcing ribs on the front and with backs twice the normal thickness. They may be furnished in either malleable or pearlitic malleable iron. 

Style B cast elevator buckets are used on inclined elevators for handling coarsely broken materials such as coke, stone, ore, etc. Clean discharge at relatively slow speeds is made possible by the low-front design. Style B buckets are furnished in either malleable or pearlitic malleable iron. 

Style C cast elevator buckets are designed to handle materials that tend to stick or pack in buckets, such as clay, sugar, salt, wet grain, and finely pulverized wet ore. Style C buckets are furnished in either malleable or pearlitic malleable iron. 

Style SC cast elevator buckets are designed primarily for handling foundry sand. SC buckets have an extra heavy body with a reinforcing band cast along the front edge and around the ends to resist abrasion, and are furnished in either malleable or pearlitic malleable iron. 

Malleable Irons. The melt treatment of malleable cast irons involves Mg, Ca, Bi, or Te additions. But malleable irons have an as-cast stmcture consisting of FcbC in a pearlitic matrix. By heat treatment in the range of 800-970 the cementite phase is transformed into graphite (TG). The cooling is controlled in such a way as to promote pearlite formation, ferrite formation, or a mixture of the two. 

Pearlitic blackheart malleable cast iron. Pearlitic blackheart malleable iron has a pearlitic rather than ferritic matrix, which provides higher strength but lower ductility than ferritic blackheart irons. It has good wear resistance and the highest strength of malleable irons. It can be hardened, and a wide range and combination of properties are possible by control of matrix microstructure. However, it is difficult to weld and requires longer heat-treatment cycle times compared with nodular cast iron. 

---