Influence of the Ti Content on the Grain Stability and the Recrystallization Behavior of Nb‐Alloyed High‐Strength Low‐Alloyed Steels

Abstract

To achieve higher strength and good hardenability and at the same time use the positive effects of thermomechanical controlled processing, the concept of Nb and Ti microalloyed steels is increasingly used for high‐strength low‐alloy (HSLA) steels with higher C contents. Herein, how the addition of Ti affects the grain growth and static recrystallization behavior of a Nb microalloyed HSLA steel with a C content of 0.23 wt% is investigated. For this reason, alloys with varying Ti and constant Nb content are produced and investigated by means of annealing and double‐hit deformation experiments. Atom probe tomography measurements reveal that the Nb concentration in the matrix decreases with increasing Ti content. Therefore, the static recrystallization behavior is steadily inhibited with decreasing Ti content, as more dissolved Nb is available for the formation of strain‐induced NbC precipitates. The annealing experiments show that the combined addition of Ti and Nb is most effective against grain coarsening, regardless of whether the Ti content is 90 or 180 ppm. To use the positive properties of Ti against grain coarsening and Nb to inhibit recrystallization, a middle content must be chosen when alloying Ti to HSLA steels with higher C content.

Effect of Coiling Temperature on Microstructures and Precipitates in High-Strength Low-Alloy Pipeline Steel after Heavy Reduction during a Six-Pass Rolling Thermo-Mechanical Controlled Process

“…In particular, CT is known to have Metals 2024, 14, 249 2 of 17 a strong effect on nano-scale precipitates [19][20][21][22][23]. For Nb-Ti HSLA pipeline steel, Nb and Ti play a significant role in achieving their strength [3,24], as the precipitation of Nb and Ti is very sensitive to CT [19,20]. For Nb-Ti micro-alloyed steel, the precipitates begin to form at a CT of 675 • C. The intermediate precipitates are small in size and randomly distributed in the matrix at a CT of 650 • C [20][21][22][23][24][25].…”

“…For Nb-Ti HSLA pipeline steel, Nb and Ti play a significant role in achieving their strength [3,24], as the precipitation of Nb and Ti is very sensitive to CT [19,20]. For Nb-Ti micro-alloyed steel, the precipitates begin to form at a CT of 675 • C. The intermediate precipitates are small in size and randomly distributed in the matrix at a CT of 650 • C [20][21][22][23][24][25]. During the coiling process in TMCP, large (Nb, Ti)C particles and small spherical (Nb, Ti)C particles form in Nb-Ti HSLA pipeline steel, which leads to dislocation pinning [21].…”

The Performance of Niobium-Microalloying Ultra-High-Strength Bridge Cable Steel during Hot Rolling

“…This process, through plastic deformation at high temperatures, enables the material to achieve the desired geometric shape and size. Simultaneously, the internal microstructure of the material undergoes a complex evolution, including recrystallization, grain growth, and phase transformation [ 5 , 11 , 14 , 15 ]. Scientific research has shown that fine control of hot-rolling parameters, such as the heating temperature, degree of deformation, deformation speed, and cooling rate, can manipulate the material’s microstructure at the microscopic level, thus achieving targeted performance design at the macroscopic scale [ 16 , 17 ].…”

Effect of Rare Earth Elements on Microstructure and Tensile Behavior of Nb-Containing Microalloyed Steels

“…High-strength microalloyed steel (HSLA) is widely utilized as the main material for offshore platforms, offshore wind power generation, and other marine engineering equipment based on its high strength, high toughness, and excellent fatigue properties [1][2][3]. Conventional HSLA steels are mainly alloyed with alloying elements such as Nb, Ti, and Cr to improve the strength and plasticity of the materials.…”