Characterization of the texture evolution in AISI 430 and AISI 433 ferritic stainless steels during simulated hot rolling

MRS Advances ◽  
2018 ◽  
Vol 3 (34-35) ◽  
pp. 1985-2002
Author(s):  
K. A. Annan ◽  
C.W. Siyasiya ◽  
W.E. Stumpf
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Stainless Steels ◽  
Hot Rolling ◽  
Strain Rates ◽  
Mean Flow ◽  
Ferritic Stainless Steels ◽  
Fibre Texture ◽  
Rolling Temperatures ◽  
Aisi 430

AbstractMulti-pass compression tests were carried out on the Gleeble-1500D® and Gleeble-3800TM® thermo-mechanical simulators to investigate the effect of temperature, strain rate and inter-pass time on the development of the texture in ferritic stainless steels (FSS) AISI 430 and 433, the latter an Al-containing variant. Orientation Distribution Functions (ODFs) through the electron backscattered diffraction (EBSD) technique was employed to characterise and study the texture present in the steels after hot working. The mean flow stress analysis showed that, the dynamic recrystallization to dynamic recovery transition temperature decreases with an increase in strain rate in both grades of stainless steels possibly allowing texture optimisation at lower hot rolling temperatures. Higher finishing rolling temperatures, lower strain rates and longer inter-pass times led to improvement in the formation of the desired γ-fibre texture which contributes to ductility or drawability in these steels. Dynamic recrystallization which promotes the formation of the desired γ-fibre texture was found to occur in both AISI 430 and 433 at temperatures above 1000 °C and strain rates less than 5 s-1. Generally AISI 433 develops a stronger gamma texture than the AISI 430 when hot rolled under similar conditions.

Dynamic Transformation during Simulated Hot Rolling

2013 ◽  
Vol 762 ◽  
pp. 1-8 ◽  
Author(s):  
John J. Jonas ◽  
Chiradeep Ghosh ◽  
Vladimir V. Basabe
Keyword(s):  
High Temperature ◽  
Dynamic Recrystallization ◽  
Hot Rolling ◽  
Strain Rates ◽  
Inverse Temperature ◽  
Mean Flow ◽  
Flow Curves ◽  
Dynamic Transformation ◽  
Critical Strains ◽  
Stress Drops

High temperature flow curves were evaluated on two Nb steels in both compression and torsion and at a series of temperatures and strain rates. The critical strains for the initiation of dynamic transformation (DT) were determined by the double differentiation method. These are shown to be distinctly lower than those associated with dynamic recrystallization (DRX). It is also evident that the compression critical strains for both DT and DRX are lower than the equivalent torsion critical strains. Mean flow stresses (MFSs) were calculated by integration from the flow curves. When plotted against inverse temperature, stress drops were observed about 30 degrees above the Ae3. These drops are shown to be caused by the dynamic transformation of austenite to ferrite, a softer phase. The characteristics of the ferrite produced dynamically are described and the transformation is shown to be displacive in nature, leading to the appearance fine Widmanstatten plates.

Influence of Hot Rolling Finishing Temperature on Texture and Ridging Resistance in Stabilized Ferritic Stainless Steels

2021 ◽  
pp. 2000695
Author(s):  
Suresh Kodukula ◽  
Heikki Kokkomäki ◽  
Esa Puukko ◽  
David Porter ◽  
Jukka Kömi
Keyword(s):  
Stainless Steels ◽  
Hot Rolling ◽  
Ferritic Stainless Steels

Characteristics of Dynamic Recrystallization during Hot Deformation for High Nitrogen Stainless Steels

2012 ◽  
Vol 715-716 ◽  
pp. 115-121
Author(s):  
Hai Wen Luo ◽  
Xu Dong Fang ◽  
Rui Zhen Wang ◽  
Zhan Yin Diao
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Strain Rates ◽  
Peak Strain ◽  
High Nitrogen ◽  
Flow Curves ◽  
Grain Sizes ◽  
Nitrogen Contents ◽  
High Nitrogen Stainless Steel

Dynamic recrystallization was studied for the stainless steels with nitrogen contents of 0.56% to 1.08% during hot deformation at temperatures of 900~1200 with strain rates ranging from 0.003 to 42 s-1. It was found that flow stress could increase remarkably with increasing nitrogen content. Flow curves during the deformation by 0.1~42/s at temperatures of 900~1200°C show a single peak, indicating the occurrence of dynamic recrystallization during deformation. The peak strain seems to decrease with increasing N content, suggesting that higher content of N facilitates dynamic recrystallization. The quenched microstructures were analyzed by optical microscopy, EBSD and TEM. The recrystallized grain sizes on the quenched specimens were measured and its dependence on temperature and strain rate was analyzed. At high temperature, continuously dynamically recrystallized microstructures were observed; whilst at low temperature, necklace-like partially recrystallized microstructures were found. Key words: High nitrogen stainless steel; dynamic recrystallization; stress-strain curves

scholarly journals Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 605
Author(s):  
Franco Lizzi ◽  
Kashyap Pradeep ◽  
Aleksandar Stanojevic ◽  
Silvana Sommadossi ◽  
Maria Cecilia Poletti
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Strain Rates ◽  
Compression Tests ◽  
Deformation Bands ◽  
Stress Softening ◽  
Relative Stress ◽  
The Matrix ◽  
Thermomechanical Processes

Inconel®718 is a well-known nickel-based super-alloy used for high-temperature applications after thermomechanical processes followed by heat treatments. This work describes the evolution of the microstructure and the stresses during hot deformation of a prototype alloy named IN718WP produced by powder metallurgy with similar chemical composition to the matrix of Inconel®718. Compression tests were performed by the thermomechanical simulator Gleeble®3800 in a temperature range from 900 to 1025 °C, and strain rates scaled from 0.001 to 10 s−1. Flow curves of IN718WP showed similar features to those of Inconel®718. The relative stress softening of the IN718WP was comparable to standard alloy Inconel®718 for the highest strain rates. Large stress softening at low strain rates may be related to two phenomena: the fast recrystallization rate, and the coarsening of micropores driven by diffusion. Dynamic recrystallization grade and grain size were quantified using metallography. The recrystallization grade increased as the strain rate decreased, although showed less dependency on the temperature. Dynamic recrystallization occurred after the formation of deformation bands at strain rates above 0.1 s−1 and after the formation of subgrains when deforming at low strain rates. Recrystallized grains had a large number of sigma 3 boundaries, and their percentage increased with strain rate and temperature. The calculated apparent activation energy and strain rate exponent value were similar to those found for Inconel®718 when deforming above the solvus temperature.

scholarly journals Dynamic recrystallization behavior of the Ta-containing TiAl alloy in isothermal deformation

2020 ◽  
Vol 321 ◽  
pp. 12008
Author(s):  
Y.Y. Luo ◽  
X.N. Mao ◽  
H.Y. Yang ◽  
Y.F. Yin ◽  
Z.Z. Zhao ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Tial Alloy ◽  
Grain Boundary Sliding ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Process ◽  
Dynamic Recrystallization Behavior ◽  
Boundary Sliding ◽  
Mechanical Twins

The dynamic recrystallization behavior of as-cast Ti-46.5Al-3Ta-2Cr-0.2W alloy during isothermal compression process with nominal deformation of 50% and strain rates from 0.01s to 1s was investigated by electron microscopy. The results showed that the deformation mechanism of this alloy can be concluded as grain boundary sliding and mechanical twins, which induce the final dynamic recrystallization. The phase boundary bulging was found to be the major nucleation mechanism responsible for the lamellar globularization and the formation of recrystallized γ grains inside the lamellar colony under the high strain rate. The recrystallized γ grains induced by the twinning is the main mechanism for refining α2 lamellar microstructures under low strain rate.

scholarly journals Mechanisms of Sticking Phenomenon Occurring during Hot Rolling of Two Ferritic Stainless Steels

2007 ◽  
Vol 38 (11) ◽  
pp. 2776-2787 ◽  
Author(s):  
Chang-Young Son ◽  
Chang Kyu Kim ◽  
Dae Jin Ha ◽  
Sunghak Lee ◽  
Jong Seog Lee ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Hot Rolling ◽  
Ferritic Stainless Steels

Investigation on Hardening and Softening Behavior of Steel after Rapid Strain Rate Changes

2016 ◽  
Vol 716 ◽  
pp. 121-128 ◽  
Author(s):  
Jens Dierdorf ◽  
Johannes Lohmar ◽  
Gerhard Hirt
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Metal Forming ◽  
Elevated Temperatures ◽  
Relaxation Behavior ◽  
Rate Change ◽  
Strain Rates ◽  
Flow Curves ◽  
Strain Rate Change

The design of industrial hot metal forming processes nowadays is mostly carried out using commercial Finite Element (FE) software codes. For precise FE simulations, reliable material properties are a crucial factor. In bulk metal forming, the most important material property is the materials flow stress, which determines the form filling and the necessary forming forces. At elevated temperatures, the flow stress of steels is determined by strain hardening, dynamic recovery and partly by dynamic recrystallization, which is dependent on strain rate and temperature. To simulate hot forming processes, which are often characterized by rapidly changing strain rates and temperatures, the flow stress is typically derived from flow curves, determined at arbitrary constant temperatures and strain rates only via linear interpolation. Hence, the materials instant reaction and relaxation behavior caused by rapid strain rate changes is not captured during simulation. To investigate the relevance of the relaxation behavior for FE simulations, trails with abrupt strain rate change are laid out and the effect on the material flow stress is analyzed in this paper. Additionally, the microstructure evolution due to the strain rate change is investigated. For this purpose, cylinder compression tests of an industrial case hardening steel are conducted at elevated temperatures and different strain rates. To analyze the influence of rapid strain rate changes, changes by one power of ten are performed at a strain of 0.3. As a reference, flow curves of the same material are determined at the initial and final constant strain rate. To investigate the microstructure evolution, compression samples are quenched at different stages, before and after the strain rate change. The results show that the flow curves after the strain rate change tend to approximate the flow curves measured for the final strain rate. However, directly after the strain rate change significant differences between the assumed instant flow stress and the real material behavior can be observed. Furthermore, it can be shown that the state of dynamic recrystallization at the time of the strain rate change influences the material response and relaxation behavior resulting in different slopes of the investigated flow curves after the strain rate change.

Deformation of ice under high internal shear stresses

1969 ◽  
Vol 6 (4) ◽  
pp. 963-968 ◽  
Author(s):  
John J. Jonas ◽  
Fritz Müller
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Polarized Light ◽  
Shear Stresses ◽  
Strain Rates ◽  
Transparent Plastic ◽  
Cross Section Area ◽  
Section Area ◽  
Polycrystalline Ice ◽  
Glacier Surges

By means of transparent plastic dies, cylindrical samples of single crystal and polycrystalline ice were extruded into rods of one quarter the original cross-section area. The deformation was carried out at −5 °C and a mean strain rate of about 10−2 s−1. With the aid of polarized light, the formation of cracks and the occurrence of dynamic recrystallization were studied. The experiments of Steinemann, and more recent results in metals suggest that, during such plastic flow, two types of dynamic recrystallization are involved. At low strain rates, the recrystallization is periodic, leading to rapid increases in strain rate at constant applied stress; at higher strain rates, the recrystallization is continuous and the strain rate is constant. The possibility that dynamic recrystallization of the periodic type is associated with glacier surges is discussed.

Sticking Mechanisms Occurring during Hot Rolling of Ferritic Stainless Steels

2007 ◽  
Vol 26-28 ◽  
pp. 3-6 ◽  
Author(s):  
Jong Seog Lee ◽  
Chang Young Son ◽  
Chang Kyu Kim ◽  
Dae Jin Ha ◽  
Sung Hak Lee ◽  
...  
Keyword(s):  
High Temperature ◽  
Stainless Steels ◽  
Hot Rolling ◽  
Material Surface ◽  
Test Results ◽  
Simulation Test ◽  
Ferritic Stainless Steels ◽  
Oxide Layers ◽  
Rolled Material ◽  
Nucleation Sites

Sticking phenomenon occurring during hot rolling of ferritic stainless steels, STS 430J1L and STS 436L, was investigated in this study. The simulation test results at 900 oC and 1000 oC revealed that STS 430J1L had a smaller number of sticking nucleation sites than the STS 436L. When the test temperature was 1070 oC, the sticking hardly occurred in both stainless steels as Fe- Cr oxide layers were formed on the surface of the rolled materials. These findings suggested that the improvement of high-temperature properties of stainless steels and the appropriate rolling conditions for readily forming oxide layers on the rolled material surface were required in order to prevent or minimize the sticking.

Cellular Automaton Simulation and Experimental Observation of the Dynamic Recrystallization of Titanium Alloy TC11 with Varied Strain Rates

2012 ◽  
Vol 476-478 ◽  
pp. 71-74
Author(s):  
Zhi Fu Yang ◽  
Qing Yuan Meng ◽  
Yu Hang Jing
Keyword(s):  
Titanium Alloy ◽  
Dislocation Density ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Cellular Automaton ◽  
Experimental Observation ◽  
Hot Working ◽  
Strain Rates ◽  
Working Process ◽  
Loading Sequence

During the metal hot working process, the dislocation density will vary with strain and strain rate, and the variation of the dislocation density will affect the grain evolution subsequently. The cellular automaton (CA) method is an effective technique used to simulate the grain evolution of materials. In this work, a dynamic recrystallization (DRX) model of titanium alloy TC11 under varied strain rates was established by the use of cellular automaton method and verified by experimental observation. Two types of loading processes called “begin fast and then slowly” and “begin slowly and then fast” were simulated to investigate the titanium alloy TC11 grain evolution processes during hot working. The simulation results are in good coincidence with experimental data. Both cellular automaton simulation and experimental results show that the flow stresses and DRX transformation percentage during hot working process of the TC11 alloy are closely related not only to the strain rate but also to the loading sequence. Compared to the “begin slowly and then fast” loading sequence, the flow stress with the “begin fast and then slowly” loading sequence is relatively smaller under the same strain rates, and the DRX transformation percentage is relatively larger.

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