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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 paper, the effect of boron addition and hot deformation on microstructure of ferrite was studied using Ti-added interstitial free (IF) steels containing different amount of B. B addition largely affected the austenite-ferrite transformation and the amount of bainitic ferrite increased with increasing B content.
Abstract: Effect of boron (B) addition and hot-deformation on microstructure of ferrite was studied using Ti-added interstitial free (IF) steels containing different amount of B. It was clarified that bainitic ferrite having typically lath or plate morphology with high dislocation density can be obtained also in plain IF steels by rapid cooling from austenite region. B addition largely affected the austenite-ferrite transformation and the amount of bainitic ferrite increased with increasing B content. Hot-deformation of austenite enhanced the transformation to polygonal or quasi-polygonal ferrite, resulting in decrease of bainitic ferrite. Interrupting compression tests indicated that enhanced transformation by hot-deformation is mainly due to grain refinement of austenite by recrystallization after hot-deformation. The cooling rate after hot-deformation produced the reversed effect of B on grain size of polygonal or quasi-polygonal ferrite. Ferrite grain size slightly decreased with increasing B content in the case of relatively large cooling rate. When the materials were cooled slowly after hot-deformation, on the other hand, the ferrite grain size increased with increasing B content. The coarse ferrite in B-bearing steels had fairly irregular shape of grain boundaries and inhomogeneous grain size, which suggested the contribution of somewhat discontinuous grain growth. This coarsening of ferrite would be responsible for the previously reported fact that B addition lowers Lankford value of cold-rolled and annealed IF steel sheets.

33 citations

Journal ArticleDOI
TL;DR: In this article, a combination of properties has been obtained for this Cu-bearing ultra-high strength steel on ageing at different temperatures, including a substantial increase in strength at 450°C, accompanied by a drop in percentage elongation, percentage reduction in area and toughness.
Abstract: On ageing at different temperatures a various combination of properties has been obtained for this Cu-bearing ultrahigh strength steel. A substantial increase in strength has been obtained at 450 °C, accompanied by a drop in percentage elongation, percentage reduction in area and toughness. At 550 °C temperature extensive ɛ-Cu precipitates have been observed. The increased strength value retained in the temperature range of 450–600 °C and a secondary hardening peak obtained at 600 °C is probably due to the formation of fine Mo carbide precipitates. The decrease in strength at 650 °C along with an increase in percentage elongation, percentage reduction in area and toughness is due to the coarsening of Cu particles and a partial recovery of matrix. At 700 °C most of the Cu precipitates become rod shaped and formation of fresh martensite with a dark contrast is observed at the lath boundaries.

33 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of strain and strain rate on deformation-induced ferrite production through strain-induced transformation (SIT) at a temperature just above Ar 3 were investigated.

33 citations

Journal ArticleDOI
TL;DR: In this article, the influence of the alloying and microalloying elements on phase transformation at different cooling rates was studied and the continuous cooling transformation diagrams were plotted in order to optimize the heat treatment and improve the mechanical properties, the range of cooling rates leading to a fully bainitic microstructure without ferrite, pearlite and especially without martensite was determined.

33 citations

Journal ArticleDOI
TL;DR: In this paper, a new kind of V-Ti-N high strength microalloyed medium carbon steel has been developed, which is used for fracture splitting connecting rod, and its characteristics of this carbon steel and its production process were investigated by optical microscope, SEM, and TEM.
Abstract: A new kind of V–Ti–N high strength microalloyed medium carbon steel has been developed, which is used for fracture splitting connecting rod. In this article, the characteristics of this carbon steel and its production process were studied. The microstructure, precipitated phases and their effects on mechanical properties were investigated by optical microscope, SEM, and TEM. The results showed that the steel was constituted of ferrite and pearlite. By reducing the finish rolling temperature and accelerating the cooling rate after rolling, microstructure with fine grain ferrite and narrow lamellar space pearlite could be obtained in V–Ti–N microalloyed medium carbon, and a large number of precipitated phases distributed over ferrite. These led the tensile strength to be more than 1000 MPa, yield strength (YS) more than 750 MPa. The impact fractograph showed typically brittle fracture characteristic.

33 citations


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