scholarly journals Measurement Uncertainty and Representation of Tensile Mechanical Properties in Metals

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1733
Author(s):  
Tingdong Xu ◽  
Kai Wang ◽  
Shenhua Song
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Measurement Uncertainty ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Elastic Deformation ◽  
Tensile Testing ◽  
New Technology ◽  
Property Variation ◽  
Technology System

The International Organization for Standardization Technical Committee for Metallic Materials—Tensile Testing stated in 2011 that temperature and strain rate variations would induce a change in the results of tensile tests, termed as the measurement uncertainty of tensile mechanical properties in metals. The uncertainty means that the tensile testing results of a specimen at a temperature and strain rate are not the original mechanical properties possessed prior to the testing. Hence, since the time of Galileo the results of tensile testing have been incorrectly interpreted as the original mechanical properties of specimens, thereby forming a paradox. At the turn of the 21st century, the micro-theory of metallic elastic deformation was proposed, identifying that a change in microstructure at atomic level could occur during elastic deformation, leading to a change in the concentration of solute (impurity) at grain boundaries/around dislocations. The micro-theory has been used to explain the mechanism of the measurement uncertainty. Different tensile temperatures and strain rates correspond to different durations of elastic deformation during tensile testing, different concentrations of solute at grain boundaries/dislocations, and thus different mechanical properties. On this basis, a new technology system of tensile testing is suggested, i.e., a “mechanical property–tensile strain rate” curve at a given test temperature can be used to evaluate the original mechanical property. The higher the strain rate is, the closer the property on the curve is to the original property. Therefore, to determine the original mechanical property of the tested metal, a sufficiently high strain rate is required. The curve can also characterize the property variation of the tested metal in service with the service time. In addition, the property characterized by a point on the curve can represent the property of the tested metal when processing-deformed with the corresponding strain rate. As an example of the application of the new technology system, the property of high-entropy alloys is represented with a curve. The results show that the new technology system could change the conceptual framework and testing technology system of metallic mechanics.

Influence of Solution Treatment on Atomic Diffusion and Mechanical Properties of AZ80 Magnesium Alloy

2012 ◽  
Vol 479-481 ◽  
pp. 27-30
Author(s):  
Ju Mei Zhang ◽  
Zhi Hu Wang ◽  
Wan Chang Sun ◽  
Li Bin Niu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Yield Strength ◽  
Grain Boundaries ◽  
Tensile Testing ◽  
Solution Treatment ◽  
Solution Time ◽  
Atomic Diffusion ◽  
Az80 Magnesium Alloy

The atomic diffusion and mechanical properties of as-cast AZ80 magnesium alloy after solution treatment at different time were studied by OM,SEM,EDS as well as tensile testing. The results show that the coarse β-Mg17Al12 phase distributed along the grain boundaries as net microstructure is almost dissolved after solution treatment, and the content of Al that in the α-Mg matrix is well distributed with the solution time prolonged. Because of the β-Mg17Al12 phase reducing and granulating, the function of precipitates phase strengthening was depressed and the hardness (HB) of alloy dropped obviously. However, the tensile strength(σb ) and elongation(δ) enhanced remarkably and the yield strength (σ0.2) decreased slightly.

Influence of plastic deformation temperature on the structure and mechanical properties of low-alloy copper alloys with Co, Ni and B

2017 ◽  
Vol 84 (2) ◽  
pp. 49-57 ◽  
Author(s):  
B. Grzegorczyk ◽  
W. Ozgowicz
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Minimum Temperature ◽  
Deformation Temperature ◽  
Tensile Testing ◽  
Copper Alloys ◽  
Testing Machine ◽  
Temperature Range ◽  
Ductility Minimum

Purpose: This work presents the influence of chemical composition and plastic deformation temperature of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys on the structure, mechanical properties and, especially on the inter-crystalline brittleness phenomenon and ductility minimum temperature effect in tensile testing with strain rate of 1.2·10-3 s-1 in the range from 20°C to 800°C. Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800°C with a strain rate of 1.2·10-3 s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Findings: Low-alloy copper alloys such as CuCo2 and CuCo2B as well as CuCoNi and CuCoNiB show a phenomenon of minimum plasticity at tensile testing in plastic deforming temperature respectively from 500°C to 700°C for CuCo2, from 450°C to 600°C for CuCo2B and from 450°C to 600°C for CuCo2B and from 500°C to 600°C for CuCoNiB. Practical implications: In result of tensile tests of copper alloys it has been found that the ductility minimum temperature of the alloys equals to about 500°C. At the temperature of stretching of about 450°C the investigated copper alloys show maximum strength values. Originality/value: Based on the test results the temperature range for decreased plasticity of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys was specified. This brittleness is a result of decreasing plasticity in a determined range of temperatures of deforming called the ductility minimum temperature.

Study on the Mechanical Property of 20Cr13 Stainless Steel Barrel Processed by Cold Radial Forging

2016 ◽  
Vol 723 ◽  
pp. 119-124
Author(s):  
Yu Hui Qi ◽  
Xiao Yun Zhang ◽  
Li Xia Fan ◽  
Cheng Xu
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Stainless Steel ◽  
New Technology ◽  
Radial Forging ◽  
Hardness Tester ◽  
The Difference ◽  
Bulging Test ◽  
Increased Strength ◽  
Anisotropic Mechanical Property

The barrel is a key part of automatic weapon. And the cold radial forging progress is a new technology for manufacturing the barrels. It will introduce some changes of the material, such as increased strength, decreased plasticity and introduction of anisotropic mechanical property. It can affect the service performance, so it is necessary to study the difference of tangential and axial mechanical properties of barrel blank and forged barrel. This paper focuses on the research of 20Cr13 stainless steel barrel. The mechanical properties of barrel blank and forged barrel are measured by the tensile, compression and bulging test. And the hardness is measured by Vickers hardness tester. The structural change of 20Cr13 stainless steel also has been observed by metalloscope in the metallographic experiment. It reveals the influence of the cold radial forging progress on the mechanical properties of 20Cr13 stainless steel barrel. And it also provides the reference data of the cold radial forging progress of 20Cr13 stainless steel.

An Improved Dynamic Constitutive Model of Dynamic Mechanical Property of Concrete

2013 ◽  
Vol 785-786 ◽  
pp. 1240-1243
Author(s):  
Pan Xiu Wang ◽  
Gui Yun Zhou
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Constitutive Model ◽  
Strain Rate ◽  
Dynamic Load ◽  
Concrete Structure ◽  
Concrete Beam ◽  
Bending Strength ◽  
Dynamic Mechanical Property ◽  
Bearing Strength

An improved dynamic constitutive model is presented, aiming to describe the key mechanical properties and predict the bearing strength of concrete structure under static and dynamic load. This model is based on the concept of equivalent uniaxial strains and strain rate. In this paper, an equivalent uniaxial stressstrain curves are obtained by the WillamWarnke curve and take the same form as in Saenz models. Then, the bending strength of a concrete beam under different static and dynamic load was discussed.

Optimization of spacer filament parameters by compressive property variation

2018 ◽  
Vol 89 (9) ◽  
pp. 1614-1622 ◽  
Author(s):  
Mei-yu Chen ◽  
Hong-Hong Wang ◽  
Ying-ying Zhou ◽  
Sun Run-jun ◽  
Xian-feng Liu
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Scientific Basis ◽  
New Method ◽  
Compressive Property ◽  
Property Variation ◽  
Consumer Concerns ◽  
Spacer Fabric

The mechanical property of a warp-knitted spacer fabric during compression results mainly from the contribution of the spacer filaments in the fabric. So, the mechanical property of a spacer filament during compression can predict that of the designed spacer fabric during compression, and then provides a scientific basis for the designers. In this work, a new method for measuring the mechanical properties of a spacer filament during compression was proposed to simulate the compression situation of a filament in a warp-knitted spacer fabric. The paper focuses on the mechanical property variation of a spacer filament with different parameters during compression. In particular, we investigated the effect of different parameters of the spacer filament on the supporting and restful properties of the corresponding spacer fabric, which is closely related to consumer concerns. Furthermore, based on the analysis of the mechanical property variation of a spacer filament with different parameters during compression, the scheme of the spacer filament parameters designed in this work was optimized.

Research on Precision Forming Technology of Car Steering Knuckle

2010 ◽  
Vol 97-101 ◽  
pp. 3060-3064 ◽  
Author(s):  
De Ying Zhao ◽  
Lian Dong Zhang ◽  
Hui Xue Sun ◽  
Li Na Sun
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Numerical Analysis ◽  
New Technology ◽  
Steering System ◽  
Forming Technology ◽  
Current Production ◽  
Production Technologies ◽  
Die Extrusion ◽  
Experimental Researches

Steering knuckle is the key part of vehicle steering system, and its mechanical properties and surface qualities are very strict. The current production technologies of branch-like steering knuckle are obsolete, which become the restriction of increasing productivity and improving the quality. Aiming at Jetta steering knuckle, the technology of two forging steps in one heat is presented. This technology is mainly composed of a closed die extrusion with the extrusion belt and open finish-forging. Experimental researches and numerical analysis show that the new technology is feasible and the mechanical property of the forging piece can be improved.

Visualization of Trapped Hydrogen Along Grain Boundaries and its Roles on Hydrogen-Induced Intergranular Fracture in Slow Strain Rate Tensile Testing of Pure Nickel

2020 ◽  
Author(s):  
Kentaro Wada ◽  
Junichiro Yamabe ◽  
Hisao Matsunaga
Keyword(s):  
Strain Rate ◽  
Grain Boundaries ◽  
Tensile Testing ◽  
Site Occupancy ◽  
Slow Strain Rate ◽  
Hydrogen Trapping ◽  
Ductility Loss ◽  
Quantitative Studies ◽  
Hydrogen Accumulation ◽  
Reduction In Area

Abstract It has been reported that hydrogen accumulation along grain boundaries (GBs) is an important process in the hydrogen embrittlement (HE) in pure Ni. However, there are no quantitative studies that elucidate the behavior of hydrogen accumulation and its effect on HE. Consequently, the segregating behavior of hydrogen along GBs and its role in intergranular (IG) fracture in pure Ni were examined in the present research, via a combination of thermal desorption analysis, secondary iron mass spectrometry, Auger electron spectroscopy and slow strain rate tensile testing. It was successfully demonstrated that the hydrogen trapped at GBs and the sulfur segregated along GBs contributed to the hydrogen-trapping. In addition, the contribution of trapped hydrogen on the hydrogen-induced ductility loss was quantitatively investigated. The results revealed a decreased reduction in area (RA) with a concomitant increase in trap-site occupancy, implying that the trapped hydrogen controlled the hydrogen-induced IG fracture and ductility loss in pure Ni.

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