Flow Stress Experimental Determination for Warm-Forming Process

2011 ◽  
Author(s):  
Ting Fai Kong ◽  
Luen Chow Chan ◽  
Tai Chiu Lee
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Room Temperature ◽  
Warm Forming ◽  
Recrystallization Temperature ◽  
Process Conditions ◽  
Compression Tests ◽  
Forming Process ◽  
Forming Temperature ◽  
Flow Stress Data

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

Warm forming process for an AA5754 train window panel

2021 ◽  
pp. 1-32
Author(s):  
Antonio Piccininni ◽  
Andrea Lo Franco ◽  
Gianfranco Palumbo
Keyword(s):  
Material Characterization ◽  
Room Temperature ◽  
Warm Forming ◽  
Railway Vehicle ◽  
Fe Model ◽  
Forming Process ◽  
Vehicle Component ◽  
Mechanical Approach ◽  
Thermal Simulations ◽  
Critical Regions

Abstract A warm forming process is designed for AA5754 to overcome low room temperature formability. The solution includes increased working temperature and is demonstrated with a railway vehicle component. A Finite Element (FE) based methodology was adopted to design the process taking into account also the starting condition of the alloy. In fact, the component's dent resistance can be enhanced if the yield point is increased accordingly: the stamping process was thus designed considering the blank in both the H111 (annealed and slightly hardened) and H32 (strain-hardened and stabilized) conditions that were preliminarily characterized. Tensile and formability tests were carried out at different temperature and strain rate levels, thus providing the data to be implemented within the FE model (Abaqus/CAE): the stamping was at first simulated at room temperature to evaluate the blank critical regions. Subsequently, the warm forming process was designed by means of an uncoupled thermo-mechanical approach. Thermal simulations were run to properly design the heating strategy and achieve an optimal temperature distribution over the blank deformation zone (according to the results of the material characterization). Such a distribution was then imported as a boundary condition into the mechanical step (Abaqus/Explicit) to determine the optimal process parameters and obtain a sound component (strain severity was monitored implementing an FLD-based damage criterion). The simulation model was validated experimentally with stamping trials to fabricate a sound component using the optimized heating strategy and punch stroke profile.

Simulation of Deform Behavior of WE43 Magnesium Alloy Based on DEFORM-3D

2009 ◽  
Vol 618-619 ◽  
pp. 191-194 ◽  
Author(s):  
Qiang Wang ◽  
Jia Cheng Gao ◽  
Wen Juan Niu
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Computational Simulation ◽  
Forming Process ◽  
Actual Operation ◽  
Actual Flow ◽  
Flow Stress Data ◽  
The Cost ◽  
Deform 3D ◽  
We43 Magnesium Alloy

Compared with the actual operation, computational simulation will save the cost and provide more valuable references or guiding significance for the real production. Using professional forming software DEFORM-3D, the upsetting process of WE43 magnesium alloy was simulated. Based on the actual flow stress data, the simulation model of WE43 magnesium alloy was created in DEFORM-3D. Results show that the uniform distribution of the temperature of WE43 magnesium alloy during the forming process is beneficial to the structural homogeneity and contributes to excellent flowing property. There is the stress concentration in the edge and slide face of the billet. So during the process of compression, the fracture will appear earlier in the edge and slide face of the sample.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

Prediction of the Flow Stress of 00Cr17Ni14Mo2 Steel during Hot Deformation

2011 ◽  
Vol 460-461 ◽  
pp. 802-805
Author(s):  
Nan Hai Hao ◽  
Shao Wei Pan
Keyword(s):  
Stainless Steel ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Strain Rates ◽  
Forming Process ◽  
Proposed Model ◽  
316L Austenitic Stainless Steel ◽  
Deformation Tests

The knowledge of the flow behavior of metals during hot deformation is of great importance in determining the optimum forming conditions. In this paper, the flow stress of 00Cr17Ni14Mo2 (ANSI 316L) austenitic stainless steel in elevated temperature is measured with compression deformation tests. The temperatures at which the steel is compressed are 800-1100°C with strain rates of 0.01-1s-1. A mathematical regression model is proposed to describe the flow stress and the validation of the model is conducted also. The proposed model can be used to predict the corresponding flow stress-strain response of 00Cr17Ni14Mo2 stainless steel in elevated temperature for the numerical simulation and design of forming process.

Low Temperature Warm Forming of Magnesium ZEK 100 Sheets for Automotive Applications

2014 ◽  
Vol 783-786 ◽  
pp. 431-436 ◽  
Author(s):  
Xiao Ping Niu ◽  
Tim Skszek ◽  
Mark Fabischek ◽  
Alex Zak
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Process Parameters ◽  
Room Temperature ◽  
Warm Forming ◽  
Automotive Applications ◽  
Forming Process ◽  
Stamping Die ◽  
Automotive Parts ◽  
Volume Production

Cosma R&D investigated a low temperature warm forming process by which a magnesium ZEK 100 door inner part with a single-stage draw depth of 144 mm was successfully formed. The warm forming process is comprised of three steps: 1) heating pre-lubricated blanks in an oven at temperatures ranging from 215°C to 260 °C, 2) robotic transfer of the heated blank to a mechanical stamping press, 3) forming of the panel in room temperature stamping die at speed of about 160 mm/s. The effect of process parameters on the formability of the part, as well as, the post-forming properties including the mechanical properties, microstructure evolution and deformation thinning are also presented. The result indicates that Magnesium ZEK 100 exhibits superior low temperature warm formability over Magnesium AZ31B, and the developed warm forming process is promising and potential for volume production of magnesium automotive parts.

Superplastic Behavior and Constitutive Equation of AZ31B Magnesium Alloy

2011 ◽  
Vol 117-119 ◽  
pp. 1689-1692
Author(s):  
Fu Xiao Chen ◽  
Xiang Zhen Chen ◽  
Fu Tao Sun
Keyword(s):  
Flow Stress ◽  
Magnesium Alloy ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Superplastic Behavior ◽  
Az31b Magnesium Alloy ◽  
Forming Temperature ◽  
Deformation Strain Rate

To study the superplasticity of AZ31B magnesium alloy, hot compression tests were performed in forming temperature range from 280°C to 440°C and strain rate range from 0.001s-1 to 0.1s-1. The influence of deformation strain rate and forming temperature on flow stress was also analyzed detailed. It was shown that the flow stress of AZ31B was very sensitive to formpng temperature and stain rate, and was decreased with deformation temperature increasing, and was increased with stain rate increasing. However, no significant change of flow stress was observed at the temperature of 440°C and the strain rate below 0.01s-1. The activation energy of AZ31B in superplastic deformation was 141.6KJ•mol-1 and its constitutive equation was established also.

Precipitation Strengthening Of Rapidly Solidified Austenitic Stainless Steels

1983 ◽  
Vol 28 ◽  
Author(s):  
J. Megusar ◽  
A. Chaudhry ◽  
D. Imeson ◽  
N. J. Grant
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Room Temperature ◽  
Mechanical Stability ◽  
Austenitic Stainless Steels ◽  
Titanium Content ◽  
Recrystallization Temperature ◽  
316 Stainless Steel ◽  
Room Temperature Yield Strength ◽  
Rapidly Solidified

ABSTRACTPrecipitation kinetics was studied in a rapidly solidified 316 stainless steel containing 0.22% C and 1% Ti. A high density of fine TiC particles was obtained by annealing at 923 to 973 K. An increase in recrystallization temperature and room temperature yield strength was observed as compared with the rapidly solidified 316 stainless steel with a nominal carbon and titanium content. An extension of solid solubility by rapid solidification thus offers a potential for developing precipitation strengthened austenitic stainless steels to improve structural and mechanical stability and likely the irradiation resistance.

Study on a Novel Electrical-Assisted Pressure Welding Process of Thin Metallic Foils

2012 ◽  
Vol 271-272 ◽  
pp. 147-151 ◽  
Author(s):  
Zhu Tian Xu ◽  
Lin Fa Peng ◽  
Pei Yun Yi ◽  
Xin Min Lai
Keyword(s):  
Stainless Steel ◽  
Electric Current ◽  
Room Temperature ◽  
Welding Process ◽  
Process Conditions ◽  
Pressure Welding ◽  
Metal Sheets ◽  
Effects Of Temperature ◽  
Metallic Foils ◽  
Joining Process

Joining of very thin metallic foils is required in vast applications such as fuel cell plates, micro reactor carriers, heat exchanger etc. Pressure welding is found to be an efficient method. However, some metals (e.g., stainless steel) are difficult to achieve successful solid state bond at room temperature. In present study, a novel electric assisted pressure welding (EAPW) process was proposed. In the EAPW process, electric current was introduced to the metal sheets under pressure welding in the purpose of reducing welding difficulty. An EAPW experimental setup was developed to study the joining process of Stainless Steel (SS) 316 sheets. The effects of electric current as well as process conditions on the final bond strength were experimentally studied. It was found that SS316 sheets could not be bonded without current at room temperature. However, they were successfully joined with electric current introduced. The co-effects of temperature and electric current were also investigated experimentally. It was found that elevated temperature caused by Joule heat is not the only reason for the improvement of the welding performance. The so-called electro-plastic effect also makes a contribution in EAPW process. Finite element method (FEM) was also employed to analyze the process and the welding behavior was discussed.

Constitutive Equation Development for Large Strain Rate Deformation Processing of 2205 Duplex Stainless Steels

2011 ◽  
Vol 695 ◽  
pp. 381-384
Author(s):  
Zhi Yu Chen ◽  
De Ning Zou ◽  
Huan Liu ◽  
Hong Bo Wang
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Strain Rate ◽  
Duplex Stainless Steel ◽  
Constitutive Equations ◽  
Large Strain ◽  
True Strain ◽  
Temperature Deformation ◽  
Compression Tests ◽  
2205 Duplex Stainless Steel

Elevated compression tests were conducted on 2205 duplex stainless steel using a Gleeble 3800 thermal simulator under constant strain rates ranging from 0.1 s−1 to 50 s−1 and at deformation temperatures ranging from 900°C to 1200°C for the sample. All tests were performed at a total true strain of 0.9. The elevated temperature deformation behavior of the 2205 duplex stainless steel was characterized based on an analysis of the stress–strain curves. A set of constitutive equations for 2205 duplex stainless steel was proposed by employing hyperbolic sine function. The equations revealed the dependence of flow stress on strain, strain rate and temperature. In order to evaluate the accuracy of the constitutive equations, the mean errors of flow stress between the experimental data and predicted results were calculated. The results showed that there was a good agreement between the prediction and experimental values.

Study on the Dent Resistance of Warm Forming HSS Parts with Free-Form Surface

2013 ◽  
Vol 365-366 ◽  
pp. 1030-1034
Author(s):  
Yu Qin Guo ◽  
Meng Zhao ◽  
Fu Zhu Li ◽  
Wei Chen ◽  
Long Chen
Keyword(s):  
High Strength Steel ◽  
Evaluation System ◽  
High Strength ◽  
Tensile Tests ◽  
Warm Forming ◽  
Free Form ◽  
Process Conditions ◽  
Forming Process ◽  
Resistance Evaluation ◽  
Free Form Surface

Recently, due to the harsh demands for automobile lightweight and safety, more and more attention is focused on the warm forming process of various high strength steel sheet. In the present work, aiming to the formed parts safety problems caused by elevating temperature, take B340/590DP steel as the research object, the dent resistance of the warm-forming parts with free-form surface is studied. Firstly, combing the warm tensile tests under various conditions with the secondary room temperature tensile tests, a secondary yield constitutive model is established for the researched material by the regression analysis method, which reveals the influences of temperature, strain rate and pre-deformation on the secondary yield behaviors. Secondly, based on the plastic deformation theory and the free-form curves and surfaces theory, a dent resistance evaluation system is proposed for the warm-forming high-strength steel parts with free-form surface. Finally, design a dent resistance model experiment, validate the dent resistance of the warm-forming B340/590DP steel specimens, and determine the relevant coefficient value in the proposed dent resistance evaluation system by means of the obtained experiment data. The research results can be used directly to select the reasonable warm-forming process conditions, control and improve the warm-forming parts quality and performances.

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