Relationship Between Bake Hardening, Snoek-Köster and Dislocation-Enhanced Snoek Peaks in Coarse Grained Low Carbon Steel

Abstract

In the present work, specimens prepared from coarse grained low carbon steel with different prestrains were baked and then, their bake hardening (BH) property and internal friction were determined. TEM was used to characterize the dislocation structure in BH treated samples. The measurements of internal friction in prestrained samples and baked samples were carried out using a multifunctional internal friction apparatus. The results indicate that, in coarse grained low carbon steel, the bake hardening properties (BH values) were negative, which were increased by increasing the prestrain from 2 to 5%, and then were decreased by increasing the prestrain from 5 to 10%. In the specimen with prestrain 5%, the BH value reached the maximum value and the height of Snoek-Köster peak was observed to be the maximum alike. With increasing the prestrain, both of the BH value and Snoek-Köster peak heights are similarly varied. It is concluded that Snoek-Köster and dislocation-enhanced Snoek peaks, caused by the interactions between interstitial solute carbon atoms and dislocations, can be used in further development of the bake hardening steels.

Keywords

• low carbon steel
• ultra-low carbon bake-hardening (ULC-BH) steel
• bake hardening (BH)
• Snoek peak
• dislocation-enhanced Snoek peak
• Snoek-Köster peak
• internal friction