Thermo-mechanical modeling of thin slab direct rolling of Nb steels

Abstract

This study presents the application of thermo-mechanical modeling of thin slab direct rolling on Nb-steels to improve mechanical and metallurgical properties of hot rolled steel strips. An integrated software model has been developed to predict and optimize final product properties based on rolling process parameters. The model calculates different rolling parameters, such as strain ( ε), critical strain ( εc), and peak strain ( εp), together with a type of recrystallization softening. The effect of changing rolling finishing temperature and interpass time on microstructure behavior and final product mechanical properties is considered. The model can handle steels with different micro-alloying elements, but only Nb-steel is presented here. The developed model has been validated online on a six-stand hot rolling line. Samples were taken from the final product and examined for mechanical properties and microstructure. Very good matching has been observed between predicted properties and corresponding values obtained from experimental examination.

Metal forming beyond shaping: Predicting and setting product properties

“…The effect of thermo-mechanical hot rolling compared to conventional rolling was investigated by Shahtout et al [197] for ten different rolling schedules with regard to the final microstructure of high strength, low carbon micro-alloyed steel (see Table 3). …”

“…29. According to the HallPetch relation, the corresponding strength alters for the four-stand schedules from 603 MPa (750 8C) to 632 MPa (800 8C) and up to 618 MPa (850 8C) [197].…”

“…One solution is to manufacture tailored welded blanks or intrinsic tailored blanks. [197]. Table 3 Measured ferrite grain size after thermo-mechanical hot rolling for different stand numbers and finishing temperatures [197].…”

“…[197]. Table 3 Measured ferrite grain size after thermo-mechanical hot rolling for different stand numbers and finishing temperatures [197]. Table 4 Cooling rate (CR), cooling temperature (CT), and measured volume fraction for ferrite and pearlite as presented in [196].…”

Finite element–based inverse approach to estimate the friction coefficient in hot bar rolling process

“…11,12 In recent years, many research groups have released research results (model-predictions and experiments) in hot rolling such as the material's outer (or inner) shape at exit, [13][14][15][16][17] roll force, [18][19][20] and material temperature. 21,22 They have not tried to measure the friction coefficient; instead, they examined the effect of oxide scale on the friction coefficient and its deformation behavior in the roll gap [23][24][25] and the effect of roll speed on the friction coefficient. 26 The exit temperature of the material (workpiece) in each pass and the effective strain and strength (hardness) evolution of the material can be possible candidates for basic parameters.…”