Topic
Microalloyed steel
About: Microalloyed steel is a research topic. Over the lifetime, 2183 publications have been published within this topic receiving 33586 citations.
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TL;DR: Tensile, hardness and room temperature Charpy V notch impact tests were conducted in this paper to evaluate the variations in the mechanical properties of a low carbon cast steel containing vanadium and titanium in the as cast condition.
Abstract: Tensile, hardness and room temperature Charpy V notch impact tests were conducted to evaluate the variations in the mechanical properties of a low carbon cast steel containing vanadium and combinations of vanadium and titanium in the as cast condition. Tensile and hardness test results indicated that good combinations of strength and ductility can be achieved by microalloying additions. The effect of titanium on the yield strength and hardness, however, strongly depended on Ti/N ratio. Ti in hyperstoichiometric amounts increased the yield strength and hardness whereas in hypostoichiometric amounts, it did not have a considerable effect on those properties. Scanning electron microscopy and optical microscopy studies revealed that coarse TiN particles were responsible for this behaviour. On the other hand, microalloying additions significantly decreased the room temperature impact energy and led to the dominance of cleavage facets on the fracture surfaces. Although coarse TiN particles were identif...
16 citations
TL;DR: In this article, the authors derived the activation energy for recrystallisation before and after precipitation, arriving at a new concept of the phenomenon that establishes discontinuous variation both in the derived function t0·5 against the inverse of the temperature and in the function itself, where t 0·5 is the time corresponding to a 50% recrystised volume fraction.
Abstract: Using torsion tests and applying the ‘back extrapolation’ method in isothermal conditions, recrystallisation–precipitation–time– temperature (RPTT) diagrams have been determined for a microalloyed steel with 0·35%C, 0·033%V, and 121 ppm N. The RPTT diagrams provide abundant information about the recrystallisation–precipitation interaction. Data such as the minimum incubation time for precipitates and the corresponding recrystallised fraction, the temperature for the minimum incubation time, and the time necessary for recrystallisation to be completed are deduced from the RPTT diagrams. The present study is completed with the determination of the activation energy for recrystallisation before and after precipitation, arriving at a new concept of the phenomenon that establishes discontinuous variation both in the derived function t0·5 against the inverse of the temperature and in the function itself, where t0·5 is the time corresponding to a 50% recrystallised volume fraction.
16 citations
TL;DR: In this article, the effect of acicular ferrite (AF) on banded structures in low-carbon microalloyed steel with Mn segregation during both isothermal transformation and continuous cooling processes was studied by dilatometry and microscopic observation.
Abstract: The effect of acicular ferrite (AF) on banded structures in low-carbon microalloyed steel with Mn segregation during both isothermal transformation and continuous cooling processes was studied by dilatometry and microscopic observation. With respect to the isothermal transformation process, the specimen isothermed at 550°C consisted of AF in Mn-poor bands and martensite in Mn-rich bands, whereas the specimen isothermed at 450°C exhibited two different morphologies of AF that appeared as bands. At a continuous cooling rate in the range of 4 to 50°C/s, a mixture of AF and martensite formed in both segregated bands, and the volume fraction of martensite in Mn-rich bands was always higher than that in Mn-poor bands. An increased cooling rate resulted in a decrease in the difference of martensite volume fraction between Mn-rich and Mn-poor bands and thereby leaded to less distinct microstructural banding. The results show that Mn segregation and cooling rate strongly affect the formation of AF-containing banded structures. The formation mechanism of microstructural banding was also discussed.
16 citations
TL;DR: In this article, the influence of deformation on the rate of coarsening of Nb(CN) was studied in 0·018%Nb steel by carbon extraction replication, and the particle size distributions were also measured after increasing amounts of strain preceded by the completion of static precipitation at 900, 925, and 975°C.
Abstract: The influence of deformation on the rate of coarsening of Nb(CN) was studied in 0·018%Nb steel by carbon extraction replication. Size distributions were determined in samples containing static precipitates which were also undergoing dynamic precipitation at 925°C. The mean particle radius r decreased while dynamic precipitation was taking place and then increased due to dynamic coarsening. It was found that the dynamic coarsening rate parameter K′ increased with increasing mean particle radius ro (ro is the mean radius after dynamic precipitation is complete and at which particle coarsening begins). In terms of the static model for particle growth, the apparent dependence of K′ on rosuggests that the particle/matrix interfacial energy increases with ro The particle size distributions were also measured after increasing amounts of strain preceded by the completion of static precipitation at 900, 925, and 975°C. At 900°C, for example, the mean radius of static precipitates was 23·5 nm, which w...
16 citations
TL;DR: In this paper, the authors examined the kinetics of abnormal grain growth in microalloyed steel containing Nb and Ti additions and found that the post-abnormal grain growth kinetics appeared to follow a simple parabolic law.
16 citations