The necessity of dynamic precipitation for the occurrence of no-recrystallization temperature in Nb-microalloyed steel

2011 ◽  
Vol 528 (3) ◽  
pp. 803-807 ◽  
Author(s):  
S.H. Mousavi Anijdan ◽  
S. Yue
Keyword(s):  
Microalloyed Steel ◽  
Recrystallization Temperature ◽  
Dynamic Precipitation ◽  
Nb Microalloyed Steel

Effect of Finishing Temperature on Mechanical Properties of a Nb-Microalloyed Steel Sheet

2010 ◽  
Vol 129-131 ◽  
pp. 1022-1028
Author(s):  
Daavood Mirahmadi Khaki ◽  
A. Akbarzadeh ◽  
Amir Abedi
Keyword(s):  
Mechanical Properties ◽  
Microalloyed Steel ◽  
Total Elongation ◽  
Controlled Rolling ◽  
Recrystallization Temperature ◽  
Effective Parameters ◽  
Steel Sheets ◽  
Intercritical Range ◽  
Nb Microalloyed Steel ◽  
Hot Rolled

Thermo mechanical processing and controlled rolling of microalloyed steel sheets are affected by several factors. In this investigation, finishing temperature of rolling which is considered as the most effective parameters on the final mechanical properties of hot rolled products has been studied. For this purpose, three different finishing temperatures of 950, 900 and 850 °C below the non-recrystallization temperature and one temperature of 800 °C in the intercritical range were chosen. It is observed that decreasing the finishing temperature causes increase of strength and decrease of total elongation. This is accompanied by more grain refinement of microstructure and the morphology was changed from polygonal ferrite to acicular one. Findings of this research provide suitable connection among finishing temperature, microstructural features, and mechanical properties of hot rolled Nb-microalloyed steel sheets.

scholarly journals Determination of Non-Recrystallization Temperature for Niobium Microalloyed Steel

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2639
Author(s):  
Mohammad Nishat Akhtar ◽  
Muneer Khan ◽  
Sher Afghan Khan ◽  
Asif Afzal ◽  
Ram Subbiah ◽  
...  
Keyword(s):  
Microalloyed Steel ◽  
Casting Process ◽  
Rolling Process ◽  
Recrystallization Temperature ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Nb Microalloyed Steel ◽  
Niobium Microalloyed Steel ◽  
Multiple Hit ◽  
Deformation Tests

In the present investigation, the non-recrystallization temperature (TNR) of niobium-microalloyed steel is determined to plan rolling schedules for obtaining the desired properties of steel. The value of TNR is based on both alloying elements and deformation parameters. In the literature, TNR equations have been developed and utilized. However, each equation has certain limitations which constrain its applicability. This study was completed using laboratory-grade low-carbon Nb-microalloyed steels designed to meet the API X-70 specification. Nb- microalloyed steel is processed by the melting and casting process, and the composition is found by optical emission spectroscopy (OES). Multiple-hit deformation tests were carried out on a Gleeble® 3500 system in the standard pocket-jaw configuration to determine TNR. Cuboidal specimens (10 (L) × 20 (W) × 20 (T) mm3) were taken for compression test (multiple-hit deformation tests) in gleeble. Microstructure evolutions were carried out by using OM (optical microscopy) and SEM (scanning electron microscopy). The value of TNR determined for 0.1 wt.% niobium bearing microalloyed steel is ~ 951 °C. Nb- microalloyed steel rolled at TNR produce partially recrystallized grain with ferrite nucleation. Hence, to verify the TNR value, a rolling process is applied with the finishing rolling temperature near TNR (~951 °C). The microstructure is also revealed in the pancake shape, which confirms TNR.

Effect of Redundant Strain on No Recrystallization Temperature in Nb Microalloyed Steel

2007 ◽  
Vol 46 (4) ◽  
pp. 467-472
Author(s):  
J. Vikram ◽  
A.M. Becerra ◽  
F. Zarandi ◽  
A.M. Elwazri ◽  
S. Yue
Keyword(s):  
Microalloyed Steel ◽  
Recrystallization Temperature ◽  
Nb Microalloyed Steel

Strain-Induced Precipitation of Nb(CN) during Deformation of Undercooled Austenite in Nb-Microalloyed HSLA Steels

2005 ◽  
Vol 475-479 ◽  
pp. 105-108 ◽  
Author(s):  
Guoan Chen ◽  
Wang Yue Yang ◽  
Shou Zhen Guo ◽  
Zu Qing Sun
Keyword(s):  
Grain Size ◽  
Incubation Period ◽  
Volume Fraction ◽  
Microalloyed Steel ◽  
Isothermal Transformation ◽  
Dynamic Precipitation ◽  
Hsla Steels ◽  
Nb Microalloyed Steel ◽  
Undercooled Austenite ◽  
Good Agreement

By using TEM strain-induced precipitation of Nb(CN) during deformation of undercooled austenite was investigated in Nb-microalloyed steel. The results showed that at 1200°C all of Nb were dissolved and there were no Nb(CN) precipitates formed during cooling until down to 760°C; During deformation enhanced ferrite transformation Nb(CN) of dynamic precipitation required an incubation period, but compared with isothermal transformation it reduced significantly. Only when the strain increased to 0.69, Nb(CN) began to precipitate on dislocation nodes and grain boundaries. Furthermore the volume fraction of Nb(CN) precipitation increased with increasing strain but their coarsening wasn’t significant. Results showed that the measured grain size is in good agreement with the calculated value.

Effect of Controlled Hot Rolling Parameters on Microstructure of a Nb-Microalloyed Steel Sheet

2011 ◽  
Author(s):  
Daavood Mirahmadi Khaki ◽  
Amir Abedi ◽  
Francisco Chinesta ◽  
Yvan Chastel ◽  
Mohamed El Mansori
Keyword(s):  
Hot Rolling ◽  
Steel Sheet ◽  
Microalloyed Steel ◽  
Nb Microalloyed Steel

Microstructure Characteristics in Continuous Cooling Transformation of an Nb Microalloyed Steel

2011 ◽  
Vol 228-229 ◽  
pp. 72-76
Author(s):  
J. H. Yang ◽  
Q. Y. Liu
Keyword(s):  
Microalloyed Steel ◽  
Controlled Rolling ◽  
Controlled Cooling ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Microstructure Characteristics ◽  
Continuous Cooling ◽  
Nb Content ◽  
Nb Microalloyed Steel ◽  
Two Stages

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a Nb microalloyed pipeline steels, the microstructure and transformation characteristics in the steel and the effect of deformation on transformation are studied. According to the results of both dilatometry measurements and microstructure observations, the continuous cooling transformation curves (CCT) of the tested steels are constructed. The results show that Nb content and deformation enhance the formation of acicular ferrite; the microstructure of the steel range from PF, QF to AF with increasing of cooling rates from 0.5 to 50°C /s in a two stages controlled rolling and the microstructure revolution is sensitive to cooling rates when it is lower than 5°C /s, however, when the cooling rate increasing further, the microstructure didn’t change very much but M/A constituents in matrix is refined and dispersed.

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