Influence of Different Levels of Cu Equivalent on the Hot Ductility of 20CrMnTi Steel

2015 ◽  
Vol 34 (5) ◽  
Author(s):  
Hong-bing Peng ◽  
Wei-qing Chen ◽  
Lie Chen ◽  
Dong Guo
Keyword(s):  
Copper Sulfide ◽  
Fracture Morphology ◽  
Hot Ductility ◽  
Ferrite Film ◽  
Austenite Grain ◽  
Ductility Trough ◽  
Proeutectoid Ferrite ◽  
Austenite Grain Boundary ◽  
Fine Copper ◽  
Different Levels

AbstractThe hot ductility of 20CrMnTi steel with different levels of Cu equivalent was investigated. The results show that Sn and Cu in 20CrMnTi steel are detrimental to its hot ductility. Sn was found to segregate to the boundaries tested by EPMA, moreover, Cu was not found to segregate to boundaries, however, the fracture morphology was examined with SEM and showed many small and shallow dimples on the fracture of steels with large Cu equivalent (>0.15) and fine copper sulfide was found from carbon extraction replicas using TEM. The adverse effect of large Cu equivalent (>0.15) on the hot ductility was due to Sn segregation and fine copper sulfide in the steel as well as their retarding the occurrence of dynamic recrystallization (DRX). The proeutectoid ferrite film precipitating along the austenite grain boundary causes the ductility trough of the five examined steels. Moreover, in this case, the level of Cu equivalent should be controlled below 0.15, which would not deteriorate the hot ductility significantly.

Hot Ductility Behavior of 800MPa Ultra High Strength Niobium Containing Steels

2013 ◽  
Vol 690-693 ◽  
pp. 227-232
Author(s):  
Qing Shan Li ◽  
Mei Zhang ◽  
Chao Bin Huang ◽  
Ru Yi Wu ◽  
Xue Zhao ◽  
...  
Keyword(s):  
Film Formation ◽  
True Strain ◽  
High Strength ◽  
Fracture Morphology ◽  
Hot Ductility ◽  
Ferrite Film ◽  
True Strain Rate ◽  
The Third ◽  
Brittle Zone ◽  
Austenite Grain Boundary

The hot ductility behavior of 800MPa ultra high strength niobium containing steels has been investigated with Gleeble3500 hot simulator. Tensile test was carried out at 650°C1300°C at a constant true strain rate of 0.001 s1. Experimental results showed that steel A has quite well ductility, and the brittle zone is narrow. Due to pro-eutectoid ferrite film formation along the prior austenite grain boundary at 650°C-750°C, samples showed a loss of hot ductility, and the fracture morphology of the specimens was brittle intercrystalline fracture, indicating the third brittle zone of the steel. However, the third brittle zone can be avoided during continuous casting, if the temperature of straightening could be kept over 800°C.

Improvement of hot ductility of C-Mn Steel containing arsenic by rare earth Ce

2018 ◽  
Vol 115 (4) ◽  
pp. 419 ◽  
Author(s):  
Wenbin Xin ◽  
Jing Zhang ◽  
Guoping Luo ◽  
Ruifen Wang ◽  
Qingyong Meng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Grain Boundary ◽  
Boundary Segregation ◽  
Fracture Morphology ◽  
Grain Boundary Segregation ◽  
Hot Ductility ◽  
Ductility Trough ◽  
Reduction Of Area ◽  
Mn Steel ◽  
Ce Content

The effect of different Ce content on the hot ductility of C-Mn steel containing arsenic was investigated at the temperature ranging from 700 to 1100 °C conducting Gleebel-1500 thermal-mechanical simulator. The reduction of area (RA%) was used to evaluate the hot ductility. The 0.16 mass% As widened the ductility trough range and especially, decreased the RA value at 850–950 °C. Conversely, adding Ce in the steel could remedy the arsenic-induced hot ductility deterioration. Moreover, with the increase of Ce content from 0 to 0.035 mass%, the RA value at 800–950 °C significantly increased, compared to that of the arsenic steel. When the content of Ce reached 0.027–0.035 mass%, the RA value at 800–850 °C was even higher than that of steel without As. Besides, the corresponding fracture morphology was changed from intergranular feature to ductile and/or interdendritic feature. Grain refinement by Ce addition, the formation of arsenious rare earth inclusions and grain boundary segregation of Ce were considered to improve the hot ductility of the steel containing As.

Influence of Aluminium on Castability of V-Microalloyed Steels

2018 ◽  
Vol 941 ◽  
pp. 83-88
Author(s):  
Kevin Mark Banks ◽  
Alison Tuling ◽  
Muthoiwa Netshilema ◽  
Marc Burty
Keyword(s):  
Grain Boundary ◽  
Sem Analysis ◽  
Microalloyed Steels ◽  
Aluminium Content ◽  
Hot Ductility ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Austenite Grain ◽  
Stress Behaviour ◽  
Austenite Grain Boundary

The influence of aluminium content on the hot ductility behaviour in V-N steels was investigated. Cylindrical specimens were subjected to thermal cycles and strain rates approximating those experienced by a conventional slab surface during continuous casting. The resulting microstructures were examined using light optical and electron microscopy and correlated with measured reduction-in-area (RA) values, calculated precipitate chemistries and volume fractions, as well as the flow stress behaviour. It was found that removal of aluminium significantly improved the hot ductility. However, increasing the total [V][N] product in Al-free steels reduces RA. Poor hot ductility is caused by low austenite grain boundary mobility characterized by high work hardening rates. The fracture mode in brittle specimens is intergranular along thin ferrite films. AlN appears to inhibit austenite grain boundary mobility in V-high N steels when the cooling rate and strain rate are both very slow as experienced during unbending. SEM analysis of fracture surfaces revealed the presence of MnS-AlN particles in microvoids. TEM-EDAX spectra showed that the larger particles observed in the Al-containing steels are mostly a constitution of duplex/triplex grain boundary precipitates, i.e., MnS-AlN and V(C,N). Conversely, good ductility in austenite is associated with high grain boundary mobility that produces fine, recrystallised grains and subsequent dimple fracture after plastic tensile stress.

Three-Dimensional Observation and Growth Kinetics of Proeutectoid Ferrite Formed at Austenite Grain Boundary in a Low Carbon Microalloyed Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4578-4583 ◽  
Author(s):  
Kai Ming Wu ◽  
A.M. Guo ◽  
Lin Cheng
Keyword(s):  
Grain Boundary ◽  
Growth Kinetics ◽  
Three Dimensional ◽  
Low Carbon ◽  
Austenite Grain ◽  
Ferrite Allotriomorphs ◽  
Proeutectoid Ferrite ◽  
Carbon Microalloyed ◽  
Austenite Grain Boundary ◽  
Kinetics Of

Three-dimensional observations of proeutectoid ferrite formed at grain boundary in an Fe-0.09%C-1.48%Mn vanadium microalloyed alloy was revealed by techniques of serial sectioning along with computer-aided reconstruction. The ferrite allotriomorphs nucleated at grain boundary edges were approximately prolate ellipsoids. Not all the ferrite allotriomorphs formed at grain boundary faces were oblate ellipsoids. The growth kinetics of ferrite allotriomorphs nucleated at grain boundary edges was greater than that of ferrite allotriomorphs nucleated at grain boundary faces.

Effect of Tin on Hot Ductility and High-temperature Oxidation Behavior of 20CrMnTi Steel

2014 ◽  
Vol 33 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Hong-bing Peng ◽  
Wei-qing Chen ◽  
Lie Chen ◽  
Dong Guo
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Bearing Steel ◽  
Hot Ductility ◽  
Temperature Oxidation ◽  
Austenite Grain ◽  
Ductility Trough ◽  
High Temperature Oxidation Behavior ◽  
Tin Content

AbstractThe hot ductility and high-temperature oxidation behavior of 20CrMnTi steel with 0.02% Cu and x% Sn (0.004 ⩽ x ⩽ 0.049) were investigated. The results show that tin has no significant effect on tensile strength of sample with less than 0.049% Sn. The critical temperature where the hot ductility reduces dramatically rises with the increase of tin content while the hot ductility decreases with its increase. The average tin content at austenite grain boundaries (GB) and substrate is 0.108% and 0.045% respectively in the specimen containing 0.049% tin quenched after heated to 1223 K and held for 600 s. Sn-segregation at the GB deteriorates the hot ductility. There is no direct relationship between the cause of the ductility trough and tin. However, Sn-segregation at the GB causes it to deepen a lot. The tin content should be controlled below 0.021%, which would not deteriorate the hot ductility significantly. There is no tin-enrichment at the scale/substrate interface when tin content is less than 0.049%. Moreover, although Sn is enriched under the steel surface, any liquid Sn-enrichment wasn't observed at the oxide/steel interface even in as high as 0.45% Sn-bearing steel with 0.02% Cu.

Cavitation control in steels of high residual element content

1980 ◽  
Vol 295 (1413) ◽  
pp. 305-305 ◽  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Prior Austenite ◽  
Low Alloy Steels ◽  
Boundary Zone ◽  
Austenite Grain ◽  
Alloy Steels ◽  
Austenite Grain Boundary ◽  
Prior Austenite Grain ◽  
Transverse Boundary

The cavitational mode of failure of prior austenite grain boundaries in bainitic creep-resisting low alloy steels is now well established as a principal factor in the high incidence of cracking problems which has developed on modern power plant in recent years. The microstructural features dominating the cavitation process at the reheat temperature in a ½CMV bainitic steel of high classical residual level have been determined. The prior austenite grain boundaries become zones of comparative weakness ca . 1 pm thick at 700 °C and are incapable of sustaining significant shear loads. Deformation is therefore initiated by a relaxation of load, through a process of prior austenite grain boundary zone shear, from inclined to transverse boundaries such that a concentration of normal stress develops across the latter. The overall deformation is thereafter determined by cavitation of the transverse boundary zones, the necessary inclined boundary displacements being accommodated by further grain boundary zone shear. Transverse boundary cavitation is shown to be an essentially time-independent process of localized ductile microvoid coalescence resulting from the plastic deformation of the boundary zone.

Effect of Pearlite Structure on the Mechanical Properties of Microalloyed Hypereutectoid Steels

2005 ◽  
Vol 500-501 ◽  
pp. 737-744 ◽  
Author(s):  
A.M. Elwazri ◽  
Steve Yue
Keyword(s):  
Mechanical Properties ◽  
Structural Evolution ◽  
Salt Bath ◽  
Austenite Grain Size ◽  
Boundary Area ◽  
Austenite Grain ◽  
Heat Treated ◽  
Hypereutectoid Steels ◽  
The Relationship ◽  
Different Levels

The relationship between mechanical properties and pearlite microstructure was investigated using various heat treatments on a hypereutectoid steels containing 1% carbon with different levels of vanadium and silicon. Specimens were heat treated at various temperatures ranging from 900 to 1200°C and transferred to salt bath conditions at 550, 580 and 620°C to examine the structural evolution of pearlite. The results show that the thickness of the cementite network increases with increasing reheat temperature. This is likely due to the larger austenite grain size reducing the grain boundary area available for proeutectoid cementite nucleation. It was found that the vanadium and silicon additions increased the strength of hypereutectoid steels through refinement of the microstructure and precipitation strengthening.

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