Tensile Properties and Creep Behavior of Compositional Modified Orthorhombic Ti2AlNb Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1549-1552 ◽  
Author(s):  
Yong Mao ◽  
Masuo Hagiwara
Keyword(s):  
Tensile Properties ◽  
Creep Strain ◽  
Room Temperature ◽  
Transient Creep ◽  
Steady State Creep ◽  
Plasma Arc ◽  
Steady State Creep Rate ◽  
Arc Melting ◽  
Cr Addition ◽  
Transient Creep Strain

Several beta stabilizing elements such as Mo, Cr, W, V and Fe have been added to Ti- 22Al-27Nb alloy for substituting a portion of Nb in order to further improve the tensile properties and creep resistances of orthorhombic Ti2AlNb-based alloys. Six compositional modified alloys Ti- 22Al-19.2Nb-2Cr, Ti-22Al-12.5Nb-2W-2Cr, Ti-22Al-10.8Nb-2Mo-2Cr, Ti-22Al-16Nb-2Cr-2V, Ti-22Al-11Nb-2Mo-1Fe, Ti-22Al-16.3Nb-2V-1Fe were prepared by plasma arc melting. The phase constitutions of these alloys were found to be B2+O or B2+O+α2 phases. The tensile properties were investigated at room temperature, and the creep behaviors were investigated under 650oC/310MPa and 650 to 750oC/200MPa. The results showed that Mo+Fe and W+Cr addition improved effectively the 0.2% yield strength and creep resistance. Ti-22Al-11Nb-2Mo-1Fe alloy exhibited the lower transient creep strain and steady-state creep rate, and longer 1% creep-strain lifetime than Ti-22Al-27Nb alloy at 650 to 700oC creep. The dislocation-controlled creep deformation mechanism was suggested to the creep behaviors of the Mo+Fe-modified alloy.

scholarly journals Effects of transient creep strain on post-tensioned concrete slabs in fire

2017 ◽  
Vol 69 (7) ◽  
pp. 337-346 ◽  
Author(s):  
Ya Wei ◽  
Francis T. K. Au ◽  
Jing Li ◽  
Neil C. M. Tsang
Keyword(s):  
Creep Strain ◽  
Transient Creep ◽  
Concrete Slabs ◽  
In Fire ◽  
Transient Creep Strain ◽  
Post Tensioned

scholarly journals Investigation of Slow Eutectoid Element on Tensile Properties and Superplasticity of a Forged SP700 Titanium Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1852
Author(s):  
Dong Han ◽  
Yongqing Zhao ◽  
Weidong Zeng ◽  
Junfeng Xiang
Keyword(s):  
Tensile Properties ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Microstructure Characteristics ◽  
Density Of Dislocations ◽  
Globular Microstructure ◽  
Β Phase ◽  
Elevated Temperature Tensile ◽  
Cr Addition

The tensile properties and superplasticity of a forged SP700 alloy with slow eutectoid element (1.5%Cr) addition were investigated in the present paper. The results of the microstructures showed that slow eutectoid element Cr has a significant influence on stabilizing the β phase and the SP700Cr alloy showed a uniform duplex and completely globular microstructure after annealing at 820 °C for 1 h and aging at 500 °C for 6 h. The results of the tensile tests showed that the yield strength, ultimate tensile strength and elongation of the alloy with optimized microstructure were 1312 MPa, 1211 MPa and 10% at room temperature, and the elongation was achieved to 1127% at 770 °C. Compared with that of the SP700 alloy, the strain rate sensitivity of the SP700Cr alloy showed a higher value. The microstructures after elevated temperature tensile tests showed that the higher density of dislocations and twins exists in SP700 alloy and the lower density of dislocations favor distribution in SP700Cr alloy. Based on the above results, the tensile properties and superplasticity of the forged SP700 alloy with 1.5% Cr addition was analyzed. In addition, microstructure characteristics were investigated by the TEM and EBSD technologies.

Room Temperature Creep Behavior and its Effect on Tensile Properties of CP-Ti

2017 ◽  
Author(s):  
Le Chang ◽  
Changyu Zhou ◽  
Xiaohua He
Keyword(s):  
Tensile Properties ◽  
Creep Strain ◽  
Creep Behavior ◽  
Room Temperature ◽  
Loading Rate ◽  
Temperature Creep ◽  
Creep Stress ◽  
Room Temperature Creep ◽  
Stress Dependent ◽  
Cp Ti

Commercial pure titanium (CP-Ti) is an attractive material, due to its good properties such as high strength, high specific work hardening ability, excellent plasticity, toughness, corrosion resistance and weld ability. It is commonly used in pressure vessels, such as heat exchangers, pumps, valves and so on. It has been reported that the room temperature creep has a great influence on the failure of titanium pressure vessel. In this paper, in order to investigate room temperature creep behavior and its effect on tensile properties of CP-Ti, both creep and tensile experiments were carried out. According to creep experiment results, CP-Ti shows strong stress dependent creep behavior at the creep stress higher than 305MPa. On the contrary, the strong loading rate dependent creep behavior occurs at the creep stress lower than 305MPa. Besides, creep strain of CP-Ti can be reduced by pretension. As pretension reaches 6%, creep behavior of CP-Ti is completely suppressed at the creep stress of 320MPa. Subsequent tensile test results show that the occurrence of room temperature creep obviously enhances the strength of CP-Ti. With the increase of creep strain and loading rate in previous creep tests, the yield strength and tensile strength of CP-Ti increase.

An Analytical Theory of the Creep Deformation of Materials

1953 ◽  
Vol 20 (2) ◽  
pp. 245-252
Author(s):  
Yoh-Han Pao ◽  
Joseph Marin
Keyword(s):  
Creep Strain ◽  
Creep Deformation ◽  
Elastic Strain ◽  
Transient Creep ◽  
Analytical Theory ◽  
Simultaneous Action ◽  
Creep Recovery ◽  
The Past ◽  
Short Time ◽  
Transient Creep Strain

Abstract This paper reports on the formulation of an analytical theory of creep. This theory is proposed for an idealized material and may be applied to those materials whose behavior conforms to that of this ideal material. The theory takes into account the initial elastic strain, the transient creep strain, and the minimum rate creep strain. Unlike previous theories, this theory is capable of representing the simultaneous action of creep and creep recovery and may be used for conditions of varying as well as constant stresses. In this respect the theory is more general than those presented in the past. The new theory is of particular importance in the design of many new military and domestic applications where high temperatures over short periods of time make the initial short-time creep strains of importance.

Effect of α2 Precipitation on Creep and Tensile Properties of Ga-Added Near-α Titanium Alloys

2018 ◽  
Vol 941 ◽  
pp. 747-752 ◽  
Author(s):  
Tomonori Kitashima ◽  
Masuo Hagiwara ◽  
Tsutomu Ito ◽  
Masao Hayakawa ◽  
Satoshi Iwasaki
Keyword(s):  
Tensile Properties ◽  
Creep Strain ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Elongation ◽  
Lamellar Microstructure ◽  
Tensile Tests ◽  
Strain Rates ◽  
Bimodal Microstructure ◽  
Creep Tests

The effect of α2precipitation on the creep and tensile properties was investigated for bimodal and lamellar microstructures in two Ga-added near-α Ti alloys with Al equivalences of 10.6 and 11.5. Fine α2phase formed in the α phase of both alloys. The volume fraction of the α2phase for the Al equivalences of 10.6 and 11.5 is equivalent to 57.6 % and 73.3 %, respectively, in the binary Ti-Al system at 600 °C. Creep tests were carried out under a constant stress of 310 MPa at 600 °C and tensile tests were performed at room temperature. Lamellar microstructure showed lower minimum creep strain rates than bimodal microstructure for both alloys. The increase in Al equivalence increased creep life by a factor of 1.6 and decreased the minimum creep strain rate from 6.51 × 10-8s-1to 3.99 × 10-8s-1in bimodal microstructure. In addition, the increase in Al equivalence decreased room temperature tensile elongation although both alloys contained a similar volume fraction of equiaxed α in a bimodal microstructure.

Interaction diagrams and failure criteria for RC columns subjected to high temperature

2020 ◽  
Vol 11 (3) ◽  
pp. 347-378
Author(s):  
Khaled Ahmed Mahmoud
Keyword(s):  
Creep Strain ◽  
Elevated Temperatures ◽  
Failure Criteria ◽  
Transient Creep ◽  
Limit Strain ◽  
Experimental Results ◽  
Content Type ◽  
Proposed Model ◽  
Ultimate Limit ◽  
Transient Creep Strain

Purpose Previous works in constructing interaction diagrams have only focused on incorporating transient creep strain implicitly in the ultimate limit strain. The present paper aims to use different approaches to define concrete ultimate limit strain (failure strain) envelops at high temperatures for preloaded and unloaded, confined and unconfined, columns during heating are proposed. These approaches are chosen to understand the effect of using different techniques to determine transient creep strain on the resulted Nu–Mu diagrams. Design/methodology/approach Transient creep strain is included within the concrete ultimate limit strain relationships, implicitly and explicitly, by four different ways, and accordingly, four different failure criteria are suggested. To define the concrete ultimate limit strain, studies are conducted to evaluate the compression strain corresponding to the maximal flexural capacity at elevated temperatures. In the analysis, the thermal and structural analyses are decoupled and, based on the resulted ultimate limit strain, the Nu – Mu diagrams are constructed at different fire exposures. Findings The validity of the proposed model is established by comparing its predictions with experimental results found in the literature. Finally, comparative calculations regarding interaction diagrams obtained by the proposed model and by other methods found in the literature are performed. It was found that the proposed model predictions agree well with experimental results. It was also found that the suggested approaches, which include simplifications, reasonably predicted the exact column capacity. Originality/value The model.

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