The hot ductility behaviour of C—Mn—Nb—Al steels and its relation to crack propagation during the straightening of concast strand

As most continuous casters used curved moulds, the as-cast strand must have sufficient hot ductility to survive the straightening operation without cracking. The influence of composition on the tendency for surface crack propagation to occur on straightening of concast strand of a commercial C—Mn-Nb-Al grade of steel, has been examined and compared with the hot ductility behaviour as measured by Gleeble tensile tests. Samples of steel with a nominal base composition of 0.15% C, 1.4% Mn, 0.03% Nb, 0.005 % N but having soluble A1 in the range < 0.01-0.07 % and P in the range 0.01-0.03 % have been solution treated to 1330 °C, cooled to test temperature and strained to fracture in the temperature range 1000-700 °C. The percentage reduction in area passed through a minimum in the temperature range 750-800 °C. Of the elements examined, soluble A1 was found to be the most deleterious to ductility for test temperatures above 850 °C. The niobium addition tended to reduce hot ductility most significantly for temperatures below 850 °C. Phosphorus, surprisingly, was found to have a small beneficial effect on hot ductility.

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The Effect of Boron Addition on Precipitation and Hot Ductility of 1.5Mn-0.1Nb-Ti Carbon Steels in As-Cast Condition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.990 ◽

2016 ◽

Vol 879 ◽

pp. 990-995 ◽

Cited By ~ 2

Author(s):

Jacek Komenda ◽

David Martin ◽

Johan Lönnqvist

Keyword(s):

Grain Boundaries ◽

Base Composition ◽

Prior Austenite ◽

Carbon Steels ◽

Hot Ductility ◽

Austenite Grain ◽

Reduction In Area ◽

Cast Condition ◽

Prior Austenite Grain ◽

Start Temperature

Twelve experimental steels with a base composition 1.5wt% Mn, 0.01 wt% V and 0.1 wt% Nb and varying C (0.05, 010 and 0.20 wt%), Ti (20 – 260 ppm) and B (0 – 100 ppm) contents have been systematically examined to quantify the effects of composition on precipitation behavio-ur and hot ductility during simulated continuous casting conditions. Nb-rich precipitates were present in the alloys with 0.10 wt-% C and 0.20 wt-% C. Alloys with 0.05, 010 and 0.20wt% C contained 50 – 100 nm size Ti-Nb carbonitrides. Boron was bound in 20 – 100 nm size boronitrides located in prior austenite grain boundaries. A Gleeble 3800 was used to study hot ductility and strain induced precipitation processes in the alloys. Alloys without B and Ti additions exhibited poor hot ductility at 850°C and 950°C, whereas the 0.05 wt-% C and 0.10 wt-% C alloys showed improved hot ductility (reduction in area 40-50%) by the addition of either >50 ppm B or 250 ppm Ti. The 0.2 wt-% C alloys showed no improvement from B or Ti additions. Examination of fracture surfaces of hot ductility specimens showed that boronitrides were located at prior austenite grain boundaries in alloys containing 80 – 100 ppm of B. Compression-relaxation tests showed that alloying with boron caused a noticeable decrease of the start temperature of strain-induced precipitation in the alloys.

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Characteristics of Embrittlement in Weather Resistant Steel in Austenite and γ-Ferrite Temperature Range

Materials Science Forum ◽

10.4028/www.scientific.net/msf.704-705.847 ◽

2011 ◽

Vol 704-705 ◽

pp. 847-852

Author(s):

Xing Jian Gao ◽

Deng Fu Chen ◽

Li Wei Song ◽

Hui Hu ◽

Xing Lei Yang ◽

...

Keyword(s):

Tensile Deformation ◽

Flow Behavior ◽

Strain Analysis ◽

Casting Process ◽

Tensile Tests ◽

Grain Boundary Sliding ◽

Hot Ductility ◽

Resistant Steel ◽

Stress Strain ◽

Temperature Range

The embrittlement of particular weather resistant steel has been investigated by thermal tensile tests using a Gleeble-1500D system at temperatures range from 600 to 1300°C and at a strain rate of 10-3/s. The specimen was reheated and cooled to the test temperature before the tensile deformation in order to get the mechanical properties subject to the continuous casting process. To make clear the plastic flow behavior in Austenite and γ-Ferrite temperature range of the weather resistant steel, the tensile tests were performed and the results indicate that the stress-strain curves as a function of temperature and with the temperature increased the stress became less, while the hot ductility changed significantly due to the work hardening and recrystallization. All of the strength indices (including yield strength, tensile strength and fracture strength) of the steel increased gradually with decreasing temperature, except for small fluctuations during the γ→α transformation occurred. Special emphases were placed on the hot ductility to clarify the sensitivity of surface cracking during unbending operation and the embrittlement zone occurred in the temperature range between 750 and 1050°C, in which the minimum %R of A was around 22% at 850°C. In the embrittlement zone, the specimens were fractured with little plastic deformation by either grain boundary sliding or by localization of strain in the film proeutectoid ferrite produced by the γ→α transformation. Keywords: Weather Resistant Steel, Embrittlement Zone, Stress-Strain Analysis, Hot Ductility, Fracture Surface.

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Effect of Vanadium and Strain Rate on Hot Ductility of Low-Carbon Microalloyed Steels

Metals ◽

10.3390/met12010014 ◽

2021 ◽

Vol 12 (1) ◽

pp. 14

Author(s):

Siying Song ◽

Junyu Tian ◽

Juan Xiao ◽

Lei Fan ◽

Yuebiao Yang ◽

...

Keyword(s):

Strain Rate ◽

Tensile Tests ◽

Vanadium Content ◽

Microalloyed Steels ◽

Hot Ductility ◽

Low Carbon ◽

Temperature Range ◽

Ferrite Transformation ◽

Ductility Trough ◽

Carbon Microalloyed

Hot tensile tests were conducted in this study to investigate the effect of strain rate (10−3 and 10 s−1) and vanadium content (0.029 and 0.047 wt.%) on the hot ductility of low-carbon microalloyed steels. The results indicate that a hot ductility trough appears at a low strain rate (10−3 s−1) because of the sufficient time for ferrite transformation and the growth of second particles, but it disappears at a high strain rate (10 s−1). The hot ductility is improved with the increase in strain rate at 700 °C or higher temperatures. In addition, with the increase in vanadium content, the large amounts of precipitate and increased ferrite transformation result in poor hot ductility of steels fractured at a low temperature range (600~900 °C). However, when the steel is fractured at a high temperature range (1000~1200 °C), more vanadium in the solid solution in the austenite inhibits the growth of parental austenite grains and results in grain refinement strengthening, slightly improving the hot ductility.

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Dynamic Crack Propagation in Single-Crystalline Silicon

MRS Proceedings ◽

10.1557/proc-539-181 ◽

1998 ◽

Vol 539 ◽

Author(s):

T. Cramer ◽

A. Wanner ◽

P. Gumbsch

Keyword(s):

Crack Propagation ◽

Crystalline Silicon ◽

Potential Drop ◽

Tensile Tests ◽

Terminal Velocity ◽

Dynamic Crack Propagation ◽

Dynamic Crack ◽

Single Crystalline Silicon ◽

Single Crystalline ◽

Crack Propagation Velocity

AbstractTensile tests on notched plates of single-crystalline silicon were carried out at high overloads. Cracks were forced to propagate on {110} planes in a <110> direction. The dynamics of the fracture process was measured using the potential drop technique and correlated with the fracture surface morphology. Crack propagation velocity did not exceed a terminal velocity of v = 3800 m/s, which corresponds to 83%7 of the Rayleigh wave velocity vR. Specimens fractured at low stresses exhibited crystallographic cleavage whereas a transition from mirror-like smooth regions to rougher hackle zones was observed in case of the specimens fractured at high stresses. Inspection of the mirror zone at high magnification revealed a deviation of the {110} plane onto {111} crystallographic facets.

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Formability and Process Conditions of Magnesium Alloy Sheets

Materials Science Forum ◽

10.4028/www.scientific.net/msf.488-489.453 ◽

2005 ◽

Vol 488-489 ◽

pp. 453-456 ◽

Cited By ~ 11

Author(s):

Shi Hong Zhang ◽

Yong Chao Xu ◽

G. Palumbo ◽

S. Pinto ◽

Luigi Tricarico ◽

...

Keyword(s):

Deep Drawing ◽

Tensile Tests ◽

Process Conditions ◽

Drawing Ratio ◽

Temperature Range ◽

Fine Grained ◽

Axial Tensile ◽

Die Surface ◽

Lower Temperature Range ◽

Lower Temperature

Comparing the formability with each other, extrusion and various rolling experiments were carried out to make fine-grained AZ31 Mg sheets, and uni-axial tensile tests were carried out at different strain rates and temperatures to investigate the effect of different variables. A warm deep drawing tool setup with heating elements, which were distributed under the die surface and inside the blank holder, was designed and manufactured, and deep drawing was performed. Extruded Mg alloy AZ31 sheets exhibit the best deep drawing ability when working in the temperature range 250-350°C. Extruded and rolled sheets of 0.8 mm thick were also deep drawn in the lower temperature range 105-170°C，showing good formability and reaching a Limit Drawing Ratio up to 2.6 at 170°C for rolled sheets. At last, a sheet cup 0.4 mm thick was deep drawn successfully at 170 °C.

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