White Cast Iron Plastic Deformation

Purpose: to identify the reasons for the high deformation plasticity of white cast iron under the usual conditions of forging production. Materials and methods: high-purity white cast irons WCI24HQ (2.42% C, 0.092% Si, 0.14% Mn, 0.007% P, 0.023% S) and WCI27HQ (2.78% C, 0.021% Si, 0.14% Mn, 0.006% P, 0.022% S) were selected as the objects of the study. The alloys chemical composition is controlled using an ARL 3460 optical emission spectrometer. Alloys were deformed on a MB-412 pneumatic hammer with the weight of falling moving parts of 150 kg. The MB-412 pneumatic hammer is designed for open die forging in small-scale production. The samples heat treatment is carried out in a laboratory chamber furnace SNOL 6/11. Structural studies are carried out using an optical microscope METAM RV-21-2. Results and discussion: it is found that the deformation of white cast iron under the usual conditions of forging production is possible only with a minimum amount of constant impurities. Modes of high-temperature intermediate annealing are developed for the process of white cast irons forging. It is shown that in the process of isothermal annealing of white cast iron, the process of ledeburite decaying into more stable eutectic carbides begins, which ensure technological plasticity for subsequent pressure treatment. It is established that the deformation accelerates the ledeburite decaying and promotes the formation of faceted eutectic carbides. The influence of the purity of white cast iron on the formation of a special morphology of excess cementite in the form of faceted eutectic carbides is studied. The morphology of excess carbide phases in the cast state, after preliminary annealing and after deformation by forging, is studied. The possibility of carbide transformations in the ledeburite of high-purity white iron during the process of isothermal annealing is elucidated. It is established that after a severe plastic deformation the structure of white cast iron becomes thermally stable due to the appearance of faceted eutectic carbides. It is determined that the structure of deformed white cast iron, due to the lack of a ledeburite component, resembles the structure of alloyed ledeburite steels. The recommendations for monitoring the formation of faceted eutectic carbides in high-purity white irons are developed.

white cast iron, wootz, steel of ledeburite class