Cold Deformation And Dissolving Mechanism Of Cementite In Steel

The prevalence of carbide in steel material is one of the most important factors thatcontrols the strength and toughness of materials. The behavior of carbide in large plasticdeformation of steel is the current hot topic of steel materials research. In this paper, it wasobtained granular cementite through spheroidizing treatment in T10steel. Colddeformation for different amount of compression executed on the samples afterspheroidizing treatment under electronic universal testing machine. Under themetallographic microscope, SEM and TEM methods, we observed and analyzed themicrostructure of original and deformation samples and studied the deformation andchanges in the concentration of cementite. Further more, it is important to comprehensiveanalyze of the deformation mechanism and cementite dissolution mechanism.The results show that T10steel get granular cementite size of1.45μm after theheating by730℃×6h with cool speed for10℃/hspheroidizing annealing and granularcementite and ferrite exist synergistic deformation under cold compression. When theamount of cold deformation is30%, the size of cementite is1.32μm. When the amount ofcold deformation increases to80%, the size of cementite is0.94μm. Therefore cementiteappears the effect of significant refining.TEM observation found that it had a large number of dislocation tangles on the ferritesubstrate and pileup dislocation was formed at the ferrite-cementite. When pileup forceexceeded the threshold, the dislocation source of cementite started, which lead to theemergence of dislocation. The larger size of cementite occurred torsional deformation. It isindicated that the cementite has a good plastic deformation capacity under thecompression at room temperature.The results of XRD and the saturation magnetization analysis show that when theT10steel cold compression is to80%, the content of cementite in steel is reduced from6.96%to6.72%. This suggests that cementite occurs dissolution under cold deformation.The carbon atoms concentration curve of deformation cementite obtained fromTEM-EELS analysis can explain that the dissolution mechanism of cementite is the mechanism of dislocation dissolution.