Microalloyed steel

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

Medium-carbon microalloyed steel for engineering machinery caterpillar chain piece and production process thereof

Abstract: The invention discloses a medium-carbon microalloyed steel for an engineering machinery caterpillar chain piece. The medium-carbon microalloyed steel comprises the following chemical components by mass percent: 0.30-0.37% of C, 0.15-0.35% of Si, 0.80-1.50% of Mn, less than or equal to 0.025% of P, 0.005-0.030% of S, less than or equal to 0.055% of Al, 0.0005-0.0035% of B, 0.008-0.15% of V, less than or equal to 0.080% of Ti, less than or equal to 0.30% of Cr, 0.05- 0.30% of Ni, 0.08- 0.35% of Cu, 0.04- 0.15% of Mo, 0.005- 0.020% of Pb, 0.003- 0.030% of Sn, and the balance of Fe and inevitable impurities. The invention also discloses a preparation method for producing the medium-carbon microalloyed steel for the engineering machinery caterpillar chain piece. The metallurgical quality, for example, surface quality, macrostructure, non-metallic inclusion, grain size, metallographic structure and the like, of the steel obtained by the method provided by the invention all meets the technical conditions.

Processing-structure-mechanical property relationship in Ti-Nb microalloyed steel: Continuous cooling versus interrupted cooling

Abstract: The process parameters associated with thermo-mechanical controlled processing (TMCP) of steels play an important role in influencing the ultimate mechanical properties. The study of TMCP parameters have not received the required attention. In this regard, we elucidate here the impact of finish cooling temperature on interrupted cooling and compare with continuous cooling on microstructural evolution and precipitation behavior and associated mechanical properties in Ti-Nb microalloyed steels. The microstructural evolution was studied via transmission electron microscopy and electron back scattered diffraction (EBSD). The microstructure of continuously cooled and interrupted cooled steels with different finish exit temperatures consisted of polygonal ferrite, bainite and martensite/austenite constituent. However, the fraction of different microstructural constituents was different in each of the experimental steels. Similarly, there were differences in the distribution and average size of (Nb, Ti)C precipitates. The aforementioned differences in the microstructure and precipitation introduced differences in tensile properties. Furthermore, electron back scattered diffraction studies indicated distinct variation in average grain area and high angle boundaries between continuously cooled and interrupted cooled steels.

Computer simulation of carbonitride precipitation during deformation in Nb-Ti microalloyed steels

Abstract: A thermo/kinetics computer model has been developed to predict the precipitation behavior of complex precipitates in Nb-Ti bearing steels under hot deformation condition. The equilibrium concentration of substitutional elements in austenite and the driving force for precipitation are calculated by the thermodynamic model. The time dependence of volume fraction and mean radius of precipitates is predicted by the kinetics model on the basis of classical nucleation and growth theory. In the kinetics model, the effect of hot deformation on precipitation is taken into account in terms of increase in nucleation sites and the enhanced diffusivity of substitutional solutes along dislocation, the decrease of solute concentration in austenite, and the driving force for precipitation are determined by a mean field approximation method. More importantly, the present model treats nucleation and growth as a concomitant process by using the finite differential method, which is different from the traditional one that treats nucleation and growth as a sequential stage. The model has been further validated by the experimental data in the literature.

Influence of martensite volume fraction on fatigue limit of a dual-phase steel

Abstract: Different dual-phase microstructures were produced in a steel containing 0.16 C (wt.%) by careful design of the heat treatment schedule in order to study the effect of microstructures, volume fraction of martensite, and epitaxial ferrite on fatigue limit. It was observed that the fatigue limit was raised by an increasing martensite content and aspect ratio, and reduced by the presence of epitaxial ferrite (new ferrite). However, these changes were very clearly and directly related to simultaneous changes in strength.

The effects of microalloyed steel pre-heat treatment on microstructure and machinability

Abstract: An extensive study was performed in finish turning of the following microalloyed steels: as received (14.3 HRc), water-cooled (44.9 HRc), air-cooled (14.41 HRc) and furnace-cooled (9.1 HRc). The turning tests were carried out using multi-layer coated cemented carbide tools at four different cutting speeds (60, 90, 120, and 150 m/min) while feedrate and depth of cut were kept constant at 0.1 mm/rev and 1 mm, respectively. The influences of workpiece microstructure and cutting speed on cutting forces and workpiece surface roughness were investigated. The worn parts of the cutting tools were also examined under a scanning electron microscope (SEM). The results showed that cutting speed significantly affected the machined surface roughness values. However, cutting forces were not influenced significantly by workpiece microstructure and cutting speed except for water cooled specimen.