The Effect of Continuous Galvanizing Process Parameters on the User Properties of Hot-Rolled Transformation Induced Plasticity Steels

Effect of Continuous Galvanizing Heat Treatments on the Microstructure and Mechanical Properties of High Al-Low Si Transformation Induced Plasticity Steels

“…This combination of strength and ductility is similar or in many cases superior to the combinations of strength and ductility obtained previously in TRIP steels using IBT temperatures of 450°C or above. [10][11][12][27][28][29][33][34][35] The occurrence of the TRIP effect was verified by XRD analysis of the uniform elongation region of the tensile samples, where it was determined that the amount of retained austenite that remained after tensile testing was too small to be quantified. The TRIP effect was also seen in the SEM analysis of the steel microstructure after tensile testing (Figures 2(c), 3(c), 4(c), and 5(c)), where it can be seen that the majority of the retained austenite had transformed to martensite.…”

“…[33][34][35] The effect of using heat treatments compatible with the continuous galvanizing thermal cycle on high Si TRIPassisted steels with 0.18 to 0.21 wt pct C was investigated by Mertens and McDermid [33] and McDermid et al [34] Mertens and McDermid [33] studied the effect of steel chemistry and IBT time when using an IBT temperature of 465°C. McDermid et al [34] studied the effect of three different thermal cycles on the structure and properties of hot rolled TRIP steel; varying the cooling rate after IA, the IBT temperature (455°C to 480°C), and the IBT time. Both of these studies showed that it was possible to obtain a good combination of strength and ductility in high Si TRIP steels using heat treatments compatible with continuous galvanizing.…”

“…A limited number of studies have been performed with IBT temperatures exceeding 450°C, [10][11][12][33][34][35] in which a number of researchers have shown that the use of higher IBT temperatures deteriorate the mechanical properties of TRIP steels. [10][11][12] In particular, Pichler et al [10] found a significant decrease in elongation when using IBT temperatures above 450°C.…”

“…[5,7,20,[33][34][35] SEM was also used to determine the critical damage processes leading to fracture of the tensile samples, in which the neck region of the fractured sample parallel to the tensile axis was analyzed. The samples were etched with 2 pct nitric acid in ethanol (2 pct nital), as described above.…”

Stability of Retained Austenite in High-Al, Low-Si TRIP-Assisted Steels Processed via Continuous Galvanizing Heat Treatments

“…Thus, it is necessary to investigate the mechanical properties and microstructures that develop as a result of the IBT taking place at 738 K (465°C). A limited number of investigations have been conducted using IBT temperatures in excess of 723 K (450°C), [17][18][19][20][21][22] which have shown both negative [18][19][20] and positive [17,21,22] effects on the mechanical properties of TRIP-assisted steels when using higher IBT temperatures. In particular, the recent study of Bellhouse and McDermid [17] addressed the use of CGL heat treatments on the microstructural development and mechanical properties of the two previously mentioned high Al, low Si TRIP-assisted steels and determined that sufficient quantities of stable RA and good mechanical properties could be obtained when using an IBT temperature of 738 K (465°C).…”