Microalloyed steel

About: Microalloyed steel is a research topic. Over the lifetime, 2183 publications have been published within this topic receiving 33586 citations.

Effect of Boron on the Hot Ductility of Low-Carbon Nb-Ti-Microalloyed Steel

Abstract: Hot tensile tests were performed to examine the effect of boron on the hot ductility of Nb-Ti-microalloyed steels. The equilibrium precipitation in the steel was predicted by Thermo-Calc calculation. The microstructure, fracture surface and precipitates in the deformed steel were examined. The results show that boron addition is favorable to improving the hot ductility of Nb-Ti-microalloyed steel. This bene cial effect is caused by the soluble boron instead of coarse BN in the steel. The hot ductility of the steel decreases less from 1000°C with increasing boron addition. The hot ductility trough shifts toward lower temperatures because ferrite formation was restrained with increasing boron content of the steel. The formation of NbC, TiN and thin lm-like ferrite along austenite grain boundaries lead to the decrease in the hot ductility of the steel. Boron addition has negligible in uence on the precipitation temperature and amount of TiN and NbC precipitates in Nb-Ti-microalloyed steel. The amount of NbC precipitates is largest in the steel, followed by TiN and BN. The precipitation temperature of BN increases considerably with further increasing the boron content. The fracture mode of Nb-Ti-microalloyed steel tends to be more ductile with the increase in the boron content of the steel. [doi:10.2320/matertrans.M2015388]

Precipitation Kinetics of Aluminium Nitride in Austenite in Microalloyed HSLA Steels

Abstract: In this work, the thermodynamic information on aluminium nitride formation and experimental precipitation kinetics data are reviewed. A revised expression for the Gibbs energy of AlN is developed with special emphasis on microalloyed steel. Using the software package MatCalc, computer simulations of AlN precipitation kinetics are performed and compared to several independent experimental results from literature. To mimic the geometrical arrangement of AlN precipitates along austenite grain boundaries, a new model for precipitation at grain boundaries is used, which takes into account fast short-circuit diffusion along grain boundaries as well as the slower bulk diffusion of atoms from inside the grain to the grain boundaries. This is essential for the calculation of AlN precipitation in austenite where nucleation occurs predominantly on grain boundaries. By studying the AlN precipitation at grain boundaries numerically, and by comparison with experimental data, it is demonstrated that the precipitation kinetics of AlN differs significantly from the simulated precipitation kinetics of randomly distributed precipitates assuming spherical diffusion fields.

Modeling of deformation and failure behavior of dissimilar resistance spot welded joints under shear, axial and combined loading conditions

Abstract: This paper presents the modeling of deformation and failure behavior of dissimilar resistance spot welded joints (RSW) between hot-stamped ultra-high strength (22MnB5) and microalloyed (HC340LAD) steels. To determine the deformation and failure behavior of the different material zones of the weld, tensile and shear specimens, which were cut from the base metals, the weld nugget and heat treated sheets were tested and modeled using the Gologanu-Leblond model coupled with the fracture criteria of Thomason and Embury. The joints were modeled using detailed 3-dimensional finite element models taking into account the different weld zones, i.e. base metal (BM), heat affected zones (HAZ) and weld metal (WM), their dimensions and their mechanical properties. Simulations of the spot welded joints’ behavior under shear, axial and combined axial and shear loading were carried out and compared to experimental results such as force vs. displacement curves, load bearing capacities, fracture mode and fracture locations. Maximum loads and force vs. displacement curves from experiments and simulations showed good agreements for all loading situations examined. Despite of its superior strength compared to the microalloyed steel, pull-out fracture of the joints took place in the coarse grain HAZ of the hot-stamped ultra-high strength steel in experiments and simulations.

Effect of cutting parameters on cutting force and surface roughness during machining microalloyed steel: Comparison between ferrite–pearlite, tempered martensite and ferrite–bainite–martensite microstructures

Abstract: Three different microstructures, namely ferrite–pearlite, tempered martensite and ferrite–bainite–martensite of 38MnSiVS5 microalloyed steel, were produced using controlled thermomechanical process...