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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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Journal ArticleDOI
TL;DR: In this article, the welding of microalloyed shipbuilding steel, AH36, using the submerged arc welding (SAW) process with one and two wires was evaluated using microhardness and Charpy V-notch testing.
Abstract: Shipbuilding is going through a period of revitalization, growth and technological advancement. One component of these innovations is to improve welding techniques and materials for optimizing processing time, reducing costs and to improve properties and ship performance. The aim of the present work is to evaluate the welding of microalloyed shipbuilding steel, AH36, using the submerged arc welding (SAW) process with one and two wires. The mechanical properties of the welded joint will be presented using microhardness and Charpy V-notch testing. For metallographic characterization, the base metal and welded joint were etched with 2% Nital and Klemm's I reagent. Scanning electron microscopy, X-ray diffraction and colored etching were used to quantify and verify the presence of martensite and retained austenite, the MA microconstituent. The results obtained from Charpy impact tests and another mechanical test can be correlated with the associated microstructure.

11 citations

Journal ArticleDOI
TL;DR: In this paper, a simple and economical heat treatment method to develop ultra-high strength cast-grade micro-alloyed steel for industrial applications is proposed, where homogenized annealed samples have been subjected to typical heat treatment cycles that consisted of repeated short-duration holding at different critical temperatures followed by forced air cooling/ice-brine quenching.
Abstract: Aim of the present study is to devise simple and economical heat treatment methods to develop ultrahigh strength cast-grade microalloyed steel for industrial applications. Typical heat treatment cycles were designed on the basis of critical temperatures, Ac 3 & Ac 1 (obtained through Thermo-Calc software) and TTT/CCT curves (constructed using JMatPro software). In this work, homogenized annealed samples have been subjected to typical heat treatment cycles that consisted of repeated short-duration holding at different critical temperatures followed by forced air cooling/ice-brine quenching. The two cycles heat treatment (i.e., holding for 6 min at Ac 3 + 50 °C followed by forced air cooling + holding at intercritical zone for 20 min followed by ice-brine quenching) has resulted a significant increase in the strength with a significant amount of ductility (UTS = 1545 MPa, hardness = 446 HV, 9% elongation). This could be attributed to the development of a typical complex microstructure consisted of degenerate pearlite, fragmented cementite and finely dispersed NbC/VC in the matrix of spider network like martensite. Development of such typical microstructure has been enlightened through the analysis of divorced eutectoid transformation and diffusion controlled mechanisms. Therefore, these heat treatments techniques could be extremely useful to develop ultrahigh strength cast grade steels economically for structural/industrial applications.

11 citations

Journal ArticleDOI
TL;DR: In this article, the applicability of different parameters obtained by means of the Electron Back Scattering Diffraction (EBSD) technique to estimate the recrystallized fraction was investigated.
Abstract: The softening processes that take place after hot deformation in two high Mn steels, one of them microalloyed with 0.1%Nb, have been investigated. Double hit torsion tests were carried out in order to determine the mechanical softening at temperatures ranging from 900 to 1100°C. In addition, the applicability of different parameters obtained by means of the Electron Back Scattering Diffraction (EBSD) technique to estimate the recrystallized fraction was investigated. It has been found that the Grain Orientation Spread (GOS) is the parameter that best allows quantifying the recrystallized fraction under the conditions investigated. The correlation between the mechanical softening and the recrystallized fraction measured by EBSD depends on the material and deformation conditions. A good correlation between both values is observed for the base steel at all the temperatures. However, for the Nb microalloyed steel, although at high temperatures a good correlation is also observed, at low temperatures the mechanical softening fraction tends to be larger than the recrystallized fraction denoting that recovery has an important contribution.

11 citations

Journal ArticleDOI
TL;DR: In this article, the refinement of coarse grained austenite in a Nb-V-Ti microalloyed steel during roughing rolling of a medium thin slab casting and direct rolling process was investigated by considering the Austenite grain size distribution.
Abstract: The refinement of coarse grained austenite in a Nb–V–Ti microalloyed steel during roughing rolling of a medium thin slab casting and direct rolling process was investigated by considering the austenite grain size distribution. The evolution of grain size distribution was analysed by taking into account dynamic recrystallisation (DRX), static recrystallisation (SRX) and metadynamic recrystallisation (MDRX), strain induced precipitation and retained strain. The results indicated that the initial coarse austenite was significantly refined during roughing rolling. Static recrystallisation is the main post-dynamic softening mechanism during all interpass intervals, but SRX+MDRX may also take place at certain times. The microstructural homogeneity of microalloyed steel produced in this work is better than that in steel produced by thin slab and direct rolling (TSDR) process. This is associated with a higher reheating temperature, a higher entry temperature and a larger reduction due to increased slab thickness ...

11 citations

Journal ArticleDOI
24 Nov 2015
TL;DR: In this paper, the initial grain size of boron microalloyed steel was investigated under different heating temperatures (1150, 1100, and 1050 °C), and hot compression tests of samples in a wide range of temperature (900 − 1100 °C) and strain rate (0.1 − 10 s−1) were conducted.
Abstract: The initial austenite grain size of boron microalloyed steel with three different amounts of boron (20, 40, and 60 ppm) was investigated under different heating temperatures (1150, 1100, and 1050 °C), and hot compression tests of samples in a wide range of temperature (900–1100 °C) and strain rate (0.1–10 s−1) were conducted. It was found that the initial austenite grain size increases with increasing temperature and boron content. The flow stress decreased with increasing boron content at lower strain rates. The flow stress constitutive equation of hot deformation was developed for the experimental steels; results showed that boron addition has the trend to reduce the hot deformation activation energy. The characteristic points of the flow curves were analyzed. Results revealed that the peak and critical stress decreased in response to an increase of boron content. The work-hardening behavior of both steels was investigated, and it was found that boron addition can decrease the work-hardening rate when strained at lower strain rates. On the contrary, peak and critical strains increased as boron content increased, indicating that boron has the ability to delay the onset of dynamic recrystallization.

11 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202328
202288
202164
202090
201986
201888