It is well known that niobium added to a wide range of steels for improving processing, microstructure, properties and performance. Over the past 20 years, use has also permitted new with attractive be developed. Furthermore, addition existing such as ferritic stainless led improvement. The goal this paper review basic behaviour in steels, including not only traditional but some newer versions. Particular emphasis been placed on metallurgical principles apply these it application allows...

Polycrystalline aggregates are comprised of three microstructural features: grain centers, boundaries, and regions affected by boundaries. It is these features that determine the mechanical properties, any advanced understanding microstructure-property relations requires their quantitative description. Traditionally, descriptions microstructures have been based on visualization, i.e., how grains appear in optical or scanning electron microscope (SEM). While this may lead to classification...

In the mid-1950s, hot rolled carbon steels exhibited high contents, coarse ferrite pearlite microstructures, and yield strengths near 300 MPa. Their ductility, toughness weldability were poor. Today, a half century later, can exhibit microstructures consisting of mixtures ferrite, bainite martensite in various proportions. These structures are very fine show over 900 MPa, with acceptable levels weldability. This advancement was made possible by combination improved steelmaking, microalloying...

A comprehensive microstructure analyses were conducted for CSP processed Nb, Ti microalloyed steel, especially focusing on the precipitation behavior of microalloying elements Nb and Ti. After coiling, steel exhibits mainly a ferrite microstructure. The average grain size is 5.3 μm. has transitional morphology from polygonal to non-polygonal characterized by moderate dislocation density 2.47E+10/cm2. high complex star-like or cruciform shaped precipitates exist in steel. They are Nb-rich...

There is an increasing interest in the progressive substitution of Si by Al TRIP steels order to obtain alloys with excellent mechanical properties and improved coatability. In this paper, thermodynamic calculations have been carried out help JMatProTM software assess compare effects that additions exert on phase transformation, carbon enrichment alloying element content phases during continuous galvanizing multiphase steels. These simulations provided important implications regarding...

From the late 1960s through 1970s, high strength microalloyed steels hot rolled to strip and plate exhibited ferrite-pearlite microstructures with yield strengths essentially limited range of 350–420 MPa. However, advent energy crisis 1970s led demand for higher strengths, while maintaining acceptable levels other properties such as weldability, toughness, formability. Since it has been recognized that strengthening mechanisms present in had reached their limit terms grain refinement solute...

It has been known for some time that steel microstructures are almost always composed of mixtures phases and microconstituents. also recognized the minor phase can often exert a major influence on final mechanical properties structural steels. Over last two decades, several important advances have made in terms which become attainable these These occurred largely through better understanding control multi-phase microstructures. The paper reviews benefits accompanied complex

In heavy steel sections, strength and toughness are improved remarkably by refining homogenizing the final ferrite microstructure. The production of sections universal-type rolling mills takes place at elevated temperature followed slow cooling rates. Therefore, refinement microstructure through modern thermomechanical, TMP, techniques is not feasible. This paper explores presents use particle-stimulated nucleation ferrite, PSN (particle-stimulated nucleation) mechanism, to refine grain size...

Microstructure and mechanical properties of two high Al, low-Si TRIP steels with different Cr Mo contents were studied using continuous galvanizing line (CGL) laboratory simulation. Combined use specific etching methods, optical electron microscopy observations EBSD characterization led to verify the epitaxial growth ferrite during cooling at a moderate rate from intercritical annealing isothermal holding temperature. The amounts “new” formed retained austenite obtained after processing are...

AbstractThe fundamental metallurgy of thermomechanical processing (TMP) has become much better understood over the past decade. An appreciation driving forces and retarding led to both a understanding existing practices development new practices. Furthermore, distinction between plate strip rolling, for example, defined, quantified, understood. This improved products, increased productivity, consistency. The information generated, first in then is slowly being adopted structural rolling...

The phenomenon of cold work embrittlement (CWE) in the P-added high strength interstitial-free steels has been associated with segregation P to ferrite grain boundaries. This by is believed decrease cohesive boundaries weakening their bonding. Hence, resistance steel brittle fracture, i.e., intergranular greatly decreased. goal present study was investigate behavior during different stages processing (prior and after coiling, rolling annealing) Ti Ti+Nb stabilized steels. It found that a...