scholarly journals Peculiarities of DRX in a Highly-Alloyed Austenitic Stainless Steel

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4004
Author(s):  
Pavel Dolzhenko ◽  
Marina Tikhonova ◽  
Rustam Kaibyshev ◽  
Andrey Belyakov
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Austenitic Stainless Steel ◽  
Dislocation Density ◽  
Strain Rate ◽  
Power Law ◽  
Peak Flow ◽  
Power Law Function ◽  
Grain Orientation Spread

The features of discontinuous dynamic recrystallization (DRX) in a highly-alloyed austenitic stainless steel were studied at temperatures of 800 °C to 1100 °C. Hot deformation accompanied by DRX was characterized by an activation energy of 415 kJ/mol. The frequency of the sequential DRX cycles depended on the deformation conditions; and the largest fraction of DRX grains with small grain orientation spread below 1° was observed at a temperature of around 1000 °C and a strain rate of about 10−3 s−1. The following power law relationships were obtained for DRX grain size (DDRX) and dislocation density (ρ) vs. temperature-compensated strain rate (Z) or peak flow stress (σP): DDRX ~ Z−0.25, ρ ~ Z0.1, σP ~ DDRX−0.9, σP ~ ρ1.4. The latter, i.e., σP ~ ρ1.4, was valid in the flow stress range below 300 MPa and changed to σP ~ ρ0.5 on increasing the stress. The obtained dependencies suggest a unique power law function between the dislocation density and the DRX grain size with an exponent of −0.5.

Regularities of Grain Refinement in an Austenitic Stainless Steel during Multiple Warm Working

2013 ◽  
Vol 753 ◽  
pp. 411-416 ◽  
Author(s):  
Andrey Belyakov ◽  
Marina Tikhonova ◽  
Zhanna Yanushkevich ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Structural Changes ◽  
Continuous Dynamic Recrystallization ◽  
Warm Working ◽  
Fine Grain ◽  
Power Law Function ◽  
Continuous Dynamic

The structural changes that are related to the new fine grain development in a chromium-nickel austenitic stainless steel subjected to warm working by means of multiple forging and multiple rolling were studied. The multiple warm working to a total strain of 2 at temperatures of 500-900C resulted in the development of submicrocrystalline structures with mean grain sizes of 300-850 nm, depending on processing conditions. The new fine grains resulted mainly from a kind of continuous reactions, which can be referred to as continuous dynamic recrystallization. Namely, the new grains resulted from a progressive evolution of strain-induced grain boundaries, the number and misorientation of which gradually increased during deformation. In contrast to hot working accompanied by discontinuous dynamic recrystallization, when the dynamic grain size can be expressed by a power law function of temperature compensated strain rate as D ~ Z-0.4, much weaker temperature/strain rate dependence of D ~ Z-0.1was obtained for the warm working.

Prediction of the Flow Stress of a High Alloyed Austenitic Stainless Steel Using Artificial Neural Network

2012 ◽  
Vol 724 ◽  
pp. 351-354 ◽  
Author(s):  
Zhao Hui Zhang ◽  
Dong Na Yan ◽  
Jian Tao Ju ◽  
Ying Han
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Stainless Steel ◽  
Flow Stress ◽  
Austenitic Stainless Steel ◽  
Strain Rate ◽  
Flow Behavior ◽  
Constitutive Relationship ◽  
Ann Model ◽  
Artificial Neural

The high temperature flow behavior of as-cast 904L austenitic stainless steel was studied using artificial neural network (ANN). Isothermal compression tests were carried out at the temperature range of 1000°C to 1200°C and strain rate range of 0.01 to 10s1. Based on the experimental flow stress data, an ANN model for the constitutive relationship between flow stress and strain, strain rate and deformation temperature was constructed by back-propagation (BP) method. Three layer structured network with one hidden layer and nine hidden neurons was trained and the normalization method was employed in training process to avoid over fitting. Modeling results show that the developed ANN model exhibits good performance for predicting the flow stresses of the 904L steel. Therefore, it can be used to reflect the hot deformation behavior in a wide working window.

Flow Curve Modelling of an Austenitic Stainless Steel at High Temperatures Starting from the One-Parameter Model of Strain Hardening

2012 ◽  
Vol 706-709 ◽  
pp. 1361-1366 ◽  
Author(s):  
Giuliano Angella
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Austenitic Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Flow Curve ◽  
Flow Curves ◽  
Rate Dependent ◽  
The One ◽  
Voce Equation

The flow curves of an austenitic stainless steel deformed at temperatures 700-1000°C with strain rates 10-5-10-2s-1were modelled with the Voce equation. The parameters needed to draw the Voce equation, are the saturation stressσVthat defines the height of the flow curve, the critical strainεCthat defines the velocity to achieveσV, and the stressσo, namely the back-extrapolated flow stress to zero strain. A modified strain hardening analysis based on the one-parameter model was used to analyze the strain hardening rate dσ/dεvs. the flow stressσin order to obtainσVandεC. The modified approach was based on the assumption that the dislocation multiplication component of strain hardening was temperature and strain rate dependent through the thermal activation termsof flow stress. A parameters’ proportional toswas obtained from the strain hardening analysis and a relationship betweens’ and temperature and strain rate was found. Relationships betweenσV,σo,εCands’ were finally established and at this stage the Voce equation could reproduce the experimental flow curves at any imposed deformation conditions of temperature and strain rate.

scholarly journals Dynamically Recrystallized Microstructures, Textures, and Tensile Properties of a Hot Worked High-Mn Steel

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Pavel Dolzhenko ◽  
Marina Tikhonova ◽  
Rustam Kaibyshev ◽  
Andrey Belyakov
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flow Stress ◽  
Power Law ◽  
Uniform Elongation ◽  
Hot Working ◽  
Gradual Change ◽  
Power Law Function ◽  
Mn Steel ◽  
True Flow

The deformation microstructures and mechanical properties were studied in a high-Mn steel subjected to hot compression. The deformation microstructures resulted from the development of dynamic recrystallization (DRX). Two DRX mechanisms, namely discontinuous and continuous, operated during warm-to-hot working. Under the conditions of hot working when the flow stresses were below 100 MPa, a power law function was obtained between the DRX grain size and the true flow stress with a grain size exponent of −0.8 owing to the discontinuous DRX. On the other hand, the gradual change in the operating DRX mechanism from a discontinuous to continuous one upon a transition from hot to warm working, when the true flow stress increases above 100 MPa, resulted in the grain size exponent of about −0.5 in the power law between the flow stress and the DRX grain size. The DRX microstructures developed by warm-to-hot working provide a beneficial combination of mechanical properties including high ultimate tensile strength in the range of 700–900 MPa and sufficient ductility with a uniform elongation well above 50%. The strengthening of the samples with DRX microstructures was attributed to the combined effect of the grain size and dislocation strengthening resulting in a rather high grain boundary strengthening factor of 570 MPa μm0.5 in the Hall-Petch-type relationship.

The Role of Grain Size on Deformation of 316H Austenitic Stainless Steel

2012 ◽  
Vol 525-526 ◽  
pp. 201-204
Author(s):  
S. Mahalingam ◽  
Peter E.J. Flewitt ◽  
A. Shterenlikht
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Rate ◽  
High Purity ◽  
Constant Strain Rate ◽  
The Other ◽  
Point Bend ◽  
Different Grain Size

The polycrystalline high purity 316H austenitic stainless steel has been thermo-mechanically treated to produce material with two layers of grain size, one of coarser and the other of finer grains. Small three point bend specimens containing a notch positioned in either the coarser or finer layer have been tested at a constant strain rate and a temperature of -196°C. The results are discussed with respect to the effect of grain size on the underlying deformation between the two layers of different grain size.

On Primary Recrystallization of High-Mn Austenitic Steels

2018 ◽  
Vol 385 ◽  
pp. 337-342
Author(s):  
Pavel Kusakin ◽  
Marina Tikhonova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Cold Rolling ◽  
Power Law ◽  
Primary Recrystallization ◽  
Austenitic Steels ◽  
Trip Steels ◽  
Fine Grained ◽  
Power Law Function ◽  
Recrystallized Grain Size

The grain refinement is an effective approach to strengthen high-Mn TWIP/TRIP steels. The development of recrystallized microstructure with a grain size of about one micron increases the yield strength of high-Mn steels above 500 MPa. The fine grained microstructures can be easily developed by cold rolling followed by primary recrystallization. The recrystallized grain size can be expressed by a power law function of the strain hardening during the previous cold rolling with an exponent of -2. Taking the dislocation density as the main strengthener, the grain size is an inverse proportion to the dislocation density. Then, the number density of recrystallized grains can be expressed by a power law function of dislocation density evolved during cold rolling with an exponent of about 2.

Sign in / Sign up

Export Citation Format

Share Document