Austenite Grain Size of Thin Slab and Its Influence on Direct Hot Strip Rolling of Nb Microalloyed Steel

2005 ◽  
pp. 295-302
Author(s):  
Hong Tao Zhang ◽  
Ganyun Pang ◽  
Rui Zhen Wang ◽  
Chengbin Liu
Keyword(s):  
Grain Size ◽  
Microalloyed Steel ◽  
Thin Slab ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Hot Strip ◽  
Nb Microalloyed Steel

Austenite Grain Size of Thin Slab and Its Influence on Direct Hot Strip Rolling of Nb Microalloyed Steel

2005 ◽  
Vol 500-501 ◽  
pp. 295-302 ◽  
Author(s):  
Hong Tao Zhang ◽  
Ganyun Pang ◽  
Rui Zhen Wang ◽  
Chengbin Liu
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Microalloyed Steel ◽  
Thin Slab ◽  
Hot Strip Rolling ◽  
Austenite Grain Size ◽  
Thick Slab ◽  
Rolling Pass ◽  
Austenite Grain ◽  
Nb Microalloyed Steel

In the production with thin slab casting a serious problem of insufficient grain refinement and microstructural inhomogeneity has been found. In this paper attention has been paid to the austenite grain size changes in thin slab of a high strength Nb microalloyed steel under as-cast conditions and after first rolling pass. For comparison, the conventional thick slab was also investigated. It was found that although as-cast thin slab shows a smaller average austenite grain size than that of as cast thick slab; the latter after reheating shows a much finer average austenite grain size. The first rolling pass at high temperature and with heavy reduction causes rapid recrystallization that contributes to austenite grain refinement.

Effect of Initial Austenite Microstructure on the Softening – Precipitation Interaction in a Low Nb Microalloyed Steel

2007 ◽  
Vol 550 ◽  
pp. 429-434 ◽  
Author(s):  
C. Iparraguirre ◽  
Ana Isabel Fernández-Calvo ◽  
Beatriz López
Keyword(s):  
Grain Size ◽  
Microalloyed Steel ◽  
Recovery Process ◽  
Precipitation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Nb Microalloyed Steel ◽  
Niobium Microalloyed Steel ◽  
Softening Fraction

The influence of initial grain size on the softening-precipitation interaction in a low niobium microalloyed steel has been investigated. The study has revealed that for the largest initial grain size (1000 μm), the recrystallised fraction remains lower than the softening fraction until relatively long times are reached. In contrast, for the smallest initial grain size (166 μm) both magnitudes are similar. As a result, precipitation interacts with recrystallisation in the case of the finest austenite grain size, whereas for the coarsest one, since recrystallisation is significantly retarded, interaction with recovery process is observed. Apparently, the initial austenite grain size does not affect precipitation kinetics.

High-Dimensional Data-Driven Optimal Design for Hot Strip Rolling of Microalloyed Steel

2018 ◽  
Vol 89 (7) ◽  
pp. 1800015 ◽  
Author(s):  
Siwei Wu ◽  
Xiaoguang Zhou ◽  
Guangming Cao ◽  
Naian Shi ◽  
Zhenyu Liu
Keyword(s):  
Optimal Design ◽  
Microalloyed Steel ◽  
High Dimensional Data ◽  
Data Driven ◽  
High Dimensional ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip

scholarly journals Effect of Initial Microstructure on the Toughness of Coarse-Grained Heat-Affected Zone in a Microalloyed Steel

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4760
Author(s):  
Minghao Shi ◽  
Man Di ◽  
Jian Zhang ◽  
Rangasayee Kannan ◽  
Jing Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Base Metal ◽  
Thermal Cycle ◽  
Microalloyed Steel ◽  
Charpy Impact ◽  
Coarse Grained ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

Toughness of the coarse-grained-heat-affected-zone (CGHAZ) strongly depends on the prior austenite grain size. The prior austenite grain size is affected not only by chemical composition, thermal cycle, and dissolution of second-phase particles, but also by the initial microstructure. The effect of base metal microstructure (ferrite/pearlite obtained by air cooling and martensite obtained by water-quenching) on Charpy impact toughness of the CGHAZ has been investigated for different heat inputs for high-heat input welding of a microalloyed steel. A welding thermal cycle with a heat input of 100 kJ/cm and 400 kJ/cm were simulated on the MMS-300 system. Despite a similar microstructure in the CGHAZ of both the base metals, the average Charpy impact energy for the air-cooled base metal was found to be higher than the water-quenched base metal. Through thermo-kinetic simulations, it was found that a higher enrichment of Mn/C at the ferrite/austenite transformation interface of the CGHAZ of water-quenched base metal resulted in stabilizing austenite at a lower A1 temperature, which resulted in a coarser austenite grain size and eventually lowering the toughness of the CGHAZ.

Microstructural Control and DWTT Toughness in Thick-Walled Nb-Ti-V Microalloyed Linepipe Steels

2005 ◽  
Vol 500-501 ◽  
pp. 303-310
Author(s):  
K.M. Banks
Keyword(s):  
Grain Size ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Roughing Mill ◽  
Fixed Composition ◽  
Exit Temperature ◽  
Linepipe Steels ◽  
Linepipe Steel ◽  
Ferrite Grain Size

Production of thick-walled low C Nb-Ti-V microalloyed linepipe steel has recently commenced in South Africa. Generally, the DWTT failures occurred when the average ferrite grain size was larger than 5µm and the pearlite colonies were coarse. This work examined the hot strip rolling behaviour of Nb-Ti-V microalloyed steel and quantified the most important parameters influencing final grain size and, hence, toughness. A Gleeble 1500 was used to both simulate hot rolling of relatively thick strip and also determine the no-recrystallisation temperature. For a fixed composition, final grain size was mainly controlled by the amount of strain applied below the norecrystallisation temperature, which was determined by the roughing mill exit temperature.

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