Recrystallization and Related Phenomena. Effect of Boron on Mechanical Properties and Recrystallization Behavior of Ti-added Ultra-low Carbon Cold-rolled Steel Sheets.

Abstract

Effect of Bon Microstructures of Hot Bands Figure 3 showsoptical microstructures of hot bands. Steels A, B and C showedpolygonal grain structure. Steel D showedthe mixture of polygonal grain structure and a small fraction of quasi-acicular ferrite. The effect of B content on the average grain diameter of hot bands is shown in Fig. 4 (Tf) were derived from the hardness change as shown in Fig. 7. T, andTf almost corresponded to the optical microstructure change. Figure 8 showsthe effect of Bon recrystallization temperature. Both T* and Tf rose with increasing B

Effect of B on Growth of Recrystallized Grain of Ti-added Ultra-low Carbon Cold-rolled Steel Sheets

“…However, B reduces the recovery rate by the interaction with dislocations. 6) Hence the softening by recovery at 5% fraction recrystallized would be same level regardless of the B content. As explained above, the decrease in the growth rate of recrystallized grains with increasing the B content was seen under the condition that the driving force for the growth of recrystallized grains was almost constant.…”

“…E l is the total energy of the unit cell without the grain boundary consisting of the atoms in the square brackets. In addition, the grain boundary segregation energy of a Ti atom ( ∆E Ti B ) when a Ti atom is arranged in the unit cell containing a B atom in the grain boundary layer was calculated using formula (7). The grain boundary segregation energy of a B atom ( ∆E B Ti ) when a B atom is arranged in the unit cell con- taining a Ti atom in the grain boundary layer was calculated using formula (8).…”

“…[2][3][4] However, it is known that the recrystallization temperature rises and the r-value decreases with B addition. 5,6) Therefore, B addition and high temperature annealing are required in the manufacturing of IF steel sheets to secure deep drawability and prevent SCWE, but such processes decrease the productivity. To solve this problem, clarification of the recrystallization suppression mechanism by B addition is required.…”

“…6) Furthermore, as steel contains more Ti, the recrystallization temperature is higher as a result of B addition, which suggests that not only B but Ti may take part in suppressing the growth of recrystallized grains. 7) B addition increases the recrystallization temperature for Ti, Nb-added ULC cold-rolled steel sheets (Ti, Nb-IF steel sheets) as well and this trend is more obvious when the Nb content is higher. 8) Thus, to clarify the recrystallization suppression mechanism by B addition in ULC cold-rolled steel sheets, it is important to pay attention to the relationship between B and substitutional solute elements.…”

Characterization of the Inhomogeneous Distribution of Light Elements in Ferritic Heat-Resistant Steels by Secondary Ion Mass Spectrometry

“…So far, several studies on analysis of inhomogeneous distribution of boron, such as grain boundary segregation of boron, in low carbon steels were carried out by using dynamic SIMS (D-SIMS). [19][20][21][22] In these studies, B + and BO2 -secondary ions were analyzed for observing the inhomogeneous distribution of boron. It is particularly found that BO2 -ions are detected in the enough sensitivity when O2 + primary ions were used.…”