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.

Study on Dynamic Recrystallization Behavior in Deformed Austenite of 52100 Steel by Using JMAK-Model

2013 ◽  
Vol 275-277 ◽  
pp. 1833-1837
Author(s):  
Ke Lu Wang ◽  
Shi Qiang Lu ◽  
Xin Li ◽  
Xian Juan Dong
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Volume Fraction ◽  
True Strain ◽  
Strain And Strain Rate ◽  
Average Grain Size ◽  
Dynamic Recrystallization Behavior ◽  
Simulation And Experiment ◽  
Good Agreement

A Johnson-Mehl-Avrami-Kolmogorov (JMAK)-model was established for dynamic recrystallization in hot deformation process of 52100 steel. The effects of hot deformation temperature, true strain and strain rate on the microstructural evolution of the steel were physically studied by using Gleeble-1500 thermo-mechanical simulator and the experimental results were used for validation of the JMAK-model. Through simulation and experiment, it is found that the predicted results of DRX volume fraction, DRX grain size and average grain size are in good agreement with the experimental ones.

Dynamic Precipitation Behaviors and Mechanical Properties of Mg-12Gd-3Y-0.5Zr Alloy Processed by Secondary Extrusion

2013 ◽  
Vol 747-748 ◽  
pp. 192-197
Author(s):  
De Jiang Li ◽  
Yin Peng Zhou ◽  
Xiao Qin Zeng ◽  
Wen Jiang Ding ◽  
Bin Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Extrusion Process ◽  
Extrusion Ratio ◽  
Water Quenching ◽  
Age Hardening ◽  
Metallographic Analysis ◽  
Air Cooling ◽  
Dynamic Precipitation ◽  
Average Grain Size

Secondary extrusion at 350 °C with the extrusion ratio of 12.25, 25 and 44 was carried out on the Mg-12Gd-3Y-0.5Zr (GW123K) alloy, and the cooling method of the secondary extruded alloys was air cooling and water quenching. Quantitative metallographic analysis method was also employed to study the distribution and volume fraction of dynamic precipitates during the extrusion process. The results showed that secondary extrusion could result in significant grain refinement and the grain size increased with extrusion ratio, which the minimum average grain size was about 5.4μm in the alloy under λ=12.25. The volume fraction of dynamic precipitates decreased with increasing extrusion ratio and the maximum volume fraction was measured to be about 49.2% in the alloy under λ =12.25. Water quenching after extrusion can effectively inhibit dynamic precipitation and the volume fraction of the precipitates ratio decreased from 41.1% after air cooling to 19.6% after water quenching in the same extrusion condition. Tensile properties results showed that the age hardening response of the alloys was decreased by dynamic precipitation and water quenching was an efficient method which is able to avoid this behavior in some extent.

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.

Influence of the Martensite Volume Fraction on the Reciprocating Sliding Behavior of Ti-Nb Microalloyed Steel

2013 ◽  
Vol 57 (1) ◽  
pp. 146-155 ◽  
Author(s):  
W. Tuckart ◽  
D. Jenko ◽  
N. Fochesatto ◽  
F. Buezas ◽  
H. Lorusso ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Microalloyed Steel ◽  
Reciprocating Sliding ◽  
Martensite Volume Fraction ◽  
Nb Microalloyed Steel

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.

scholarly journals Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Ductile Iron ◽  
Volume Fraction ◽  
Energy Impact ◽  
Treatment Conditions ◽  
Mold Casting ◽  
Grade 3 ◽  
Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

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
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