Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

Experimental Investigation of Ti-6Al-4V with a Biaxial Tensile Test Setup at Elevated Temperature

2014 ◽  
Vol 622-623 ◽  
pp. 273-278 ◽  
Author(s):  
Marion Merklein ◽  
Sebastian Suttner ◽  
Adam Schaub
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Plastic Yielding ◽  
Characterization Methods ◽  
Specific Strength ◽  
Biaxial Tensile ◽  
Stress States

The requirement for products to reduce weight while maintaining strength is a major challenge to the development of new advanced materials. Especially in the field of human medicine or aviation and aeronautics new materials are needed to satisfy increasing demands. Therefore the titanium alloy Ti-6Al-4V with its high specific strength and an outstanding corrosion resistance is used for high and reliable performance in sheet metal forming processes as well as in medical applications. Due to a meaningful and accurate numerical process design and to improve the prediction accuracy of the numerical model, advanced material characterization methods are required. To expand the formability and to skillfully use the advantage of Ti-6Al-4V, forming processes are performed at elevated temperatures. Thus the investigation of plastic yielding at different stress states and at an elevated temperature of 400°C is presented in this paper. For this reason biaxial tensile tests with a cruciform shaped specimen are realized at 400°C in addition to uniaxial tensile tests. Moreover the beginning of plastic yielding is analyzed in the first quadrant of the stress space with regard to complex material modeling.

Failure Prediction in Drawing Processes of Mg Alloy Sheet by the FEM and Ductile Fracture Criterion

2011 ◽  
Vol 264-265 ◽  
pp. 813-818 ◽  
Author(s):  
Sang Woo Kim ◽  
Young Seon Lee ◽  
Beom Soo Kang
Keyword(s):  
Ductile Fracture ◽  
Fracture Criterion ◽  
Elevated Temperatures ◽  
Failure Prediction ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Fe Analysis ◽  
Uniaxial Tensile ◽  
Ductile Fracture Criterion

In this work, in order to predict the forming failure of AZ31 magnesium alloy sheet in drawing process at elevated temperatures, a series of square cup tests at various temperatures and FE analyses were carried out. The critical damage values and the mechanical properties dependent on strain rates and temperatures were evaluated from uniaxial tensile tests and those were utilized to the forming failure prediction using FE analysis. Based on the plastic deformation history obtained from FE analysis and Cockcroft and Latham’s ductile fracture criterion, the fracture initiation time and location were predicted and verified with the experimental results.

Mechanical Behavior Characterization of Magnesium Alloy Sheets at Warm Temperature

2015 ◽  
Vol 32 (4) ◽  
pp. 391-399
Author(s):  
J. Huang ◽  
Y. Yuan ◽  
H. Liu ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Magnesium Alloy ◽  
Mechanical Behavior ◽  
Yield Criterion ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Uniaxial Tensile ◽  
Compression Tests ◽  
Warm Temperature ◽  
Yield Anisotropy

AbstractMagnesium (Mg) alloy sheet has received increasing attention in automotive, transportation, and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. To better understand the warm forming properties of magnesium alloy sheet, an accurate description of the mechanical behavior at elevated temperature is required.In this paper, both uniaxial tensile tests and uniaxial compression tests were carried out at warm temperature for Mg AZ31B alloy sheets. The tensile tests were conducted under various strain rates and material orientations, while the compression tests only considered different material orientations. Based on the orthotropic yield criterion for hexagonal close packed (HCP) metals proposed by Cazacu et al., 2006, a viscoplasticity model has been developed to describe the initial yield anisotropy and asymmetry hardening behavior in tensile and compression of Mg sheet. This model was incorporated into ABAQUS through a user-defined material subroutine. The numerical results show a good agreement with experimental data in a large range of deformation.

Research on Superplasticity of Supplied 5A06 Aluminium Alloy Sheet

2016 ◽  
Vol 838-839 ◽  
pp. 127-131
Author(s):  
Bao Peng Bi ◽  
Yong Wang
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
Alloy Sheet ◽  
Uniaxial Tensile ◽  
5A06 Aluminum Alloy ◽  
Bulging Test

Superplasticity of supplied 5A06 aluminum alloy is reviewed in this paper. Supplied 5A06 aluminum alloy is researched on superplasticity by the methods of same strain rate high temperature uniaxial tensile tests at temperature range375°C-500°Cand strain rate range 2.5×10-4s-1~1.0×10-2s-1. Microstructure and fracture of tensile samples are analyzed and discussed, deduce that grain boundary sliding (GBS) is the predominant deformation mechanism. Superplastic formability of the alloy is evaluated by gas bulging test at elevated temperatures. Gas bulging test demonstrates the deformation process parameters for the best superplastic formability is 400°Cand 0.005s-1 ,suggesting good application prospect for this aluminum alloy.

Superplasticity and Superplastic Formability of Hot-Rolled AZ31 Magnesium Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 231-235
Author(s):  
D.L. Yin ◽  
C.W. Wang ◽  
Jing Tao Wang ◽  
Yan Dong Yu
Keyword(s):  
Threshold Stress ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Strain Rate Range ◽  
Dome Height ◽  
Uniaxial Tensile ◽  
Az31 Mg Alloy ◽  
Bulging Test ◽  
Hot Rolled

The superplasticity of a hot-rolled AZ31 Mg alloy was investigated by uniaxial tensile tests at temperature range 250-450oC and strain rate range 0.7×10-3-1.4×10-1s-1. Superplastic formability of the alloy was evaluated by gas bulging test at elevated temperatures. The threshold stress for grain boundary sliding (GBS) was calculated and the topography during superplastic deformation was observed by SEM. It is found that, at 400 oC and 0.7×10-3 s-1, the maximum elongation reaches 362.5%. GBS is the predominant deformation mechanism and characterized by a pronounced improvement in homogeneity with increasing temperatures, indicating a transformation of GBS mode from cooperative GBS (CGBS) to individual GBS (IGBS). The improved homogeneity of GBS can be interpreted in terms of decreased threshold stress with increasing temperatures. Gas bulging test demonstrates that the temperature for the best superplastic formability is 400 oC and a hemispherical part with a specific limiting dome height of 0.51 was obtained, suggesting good application prospect for this alloy.

Formability Characteristics of AA5083 Sheets under Hot Forming Conditions

2013 ◽  
Vol 549 ◽  
pp. 356-363
Author(s):  
Stefania Bruschi ◽  
Andrea Ghiotti ◽  
Francesco Michieletto
Keyword(s):  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Superplastic Forming ◽  
Tensile Tests ◽  
Processing Route ◽  
Strain Rates ◽  
Fine Grained ◽  
Axial Tensile

The production of aluminum alloy components through sheet forming processes conducted at elevated temperatures is gaining more and more interest as it gives raise to the possibility of a significant enhancement of the metal formability characteristics, compared to room temperature forming. Aluminum alloy AA5083 blanks, which present a limited formability at room temperature, are usually formed through superplastic forming at elevated temperature: however, this processing route is too slow to be applicable for large batch production, typical for instance of the automotive industry. The paper is aimed at exploring the formability characteristics of the AA5083 when deformed at elevated temperature, but in a range of strain rates higher than those usually applicable in superplastic forming. To this aim, uni-axial tensile tests were carried out, in order to record the material formability characteristics as a function of temperature and strain rate, and to correlate them with the developed microstructural features. It is shown that it is possible to work at higher strain rates, still preserving a significant formability, even without using a conventional fine-grained superplastic alloy.

Mechanical Behavior of 980MPa NANOHITENTM at Elevated Temperatures and its Effect on Springback in Warm Forming

2014 ◽  
Vol 611-612 ◽  
pp. 11-18 ◽  
Author(s):  
Toru Minote ◽  
Yoshimasa Funakawa ◽  
Naoko Saito ◽  
Mitsugi Fukahori ◽  
Hiroshi Hamasaki ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Stress Relaxation ◽  
Mechanical Behavior ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Warm Forming ◽  
Bending Test ◽  
Uniaxial Tensile ◽  
High Tensile Strength

High tensile strength steel sheets have large springback after being formend at room temperature. Warm forming can be a solution to reduce springback of high tensile strength steel parts. NANOHITENTM is a high strength ferritic steel precipitation-strengthened by nanometer-sized carbides developed by JFE Steel Corporation. Tensile strength of the steel at room temperature does not change before and after deformation at elevated temperatures up to 873K since the carbides in the steel are stable at high temperatures less than 973K. Therefore, the steel is suitable for warm forming. Springback of 980MPa NANOHITENTM parts warm formed at 873K is the same level of that of cold formed conventional 590MPa steel parts. In this study, two kinds of material testing at room temperature and at elevated temperatures between 573K and 937K were performed to understand the mechanical behavior of 980MPa NANOHITENTM: uniaxial tensile tests and bending tests. The steels flow stress depends on not only material temperature but also strain rate in uniaxial tensile tests. After a bending test, the specimen shows springback measured by the change of an angle between the two sides. Stress relaxation happens while a test specimen is held at the bottom dead point after bending. And the stress relaxation could be used to reduce springback of warm formed parts.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Magnesium Sheet Metal Forming Considering its Specific Yield Behavior

2005 ◽  
Vol 6-8 ◽  
pp. 771-778 ◽  
Author(s):  
M. Redecker ◽  
Karl Roll ◽  
S. Häussinger
Keyword(s):  
Sheet Metal ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Specific Yield ◽  
Forming Limit ◽  
Forming Process ◽  
Local Flow ◽  
Yield Behavior ◽  
Magnesium Sheet ◽  
Testing Procedures

In recent years very strong efforts have been undertaken to build light weight structures of car bodies in the automotive industry. Structural technologies like Space Frame, tailored blanks and relief-embossed panels are well-known and already in use. Beside that there is a large assortment of design materials with low density or high strength. Magnesium alloys are lighter by approximately 34 percent than aluminum alloys and are considered to be the lightest metallic design material. However forming processes of magnesium sheet metal are difficult due to its complex plasticity behavior. Strain rate sensitivity, asymmetric and softening yield behavior of magnesium are leading to a complex description of the forming process. Asymmetric yield behavior means different yield stress depending on tensile or compressive loading. It is well-known that elevated temperatures around 200°C improve the local flow behavior of magnesium. Experiments show that in this way the forming limit curves can be considerably increased. So far the simulation of the forming process including temperature, strain rates and plastic asymmetry is not state-of-the-art. Moreover, neither reliable material data nor standardized testing procedures are available. According to the great attractiveness of magnesium sheet metal parts there is a serious need for a reliable modeling of the virtual process chain including the specification of required mechanical properties. An existing series geometry which already can be made of magnesium at elevated temperatures is calculated using the finite element method. The results clarify the failings of standard calculation methods and show potentials of its improvement.

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