Low-temperature plastic strain of ultrafine-grain aluminum

2008 ◽  
Vol 34 (8) ◽  
pp. 665-671 ◽  
Author(s):  
Yu. Z. Éstrin ◽  
N. V. Isaev ◽  
T. V. Grigorova ◽  
V. V. Pustovalov ◽  
V. S. Fomenko ◽  
...  
Keyword(s):  
Low Temperature ◽  
Plastic Strain ◽  
Ultrafine Grain

Study of the structural nonuniformity and low-temperature micromechanical properties of ultrafine-grain aluminum

2008 ◽  
Vol 34 (9) ◽  
pp. 771-776 ◽  
Author(s):  
Yu. Z. Éstrin ◽  
L. S. Fomenko ◽  
S. V. Lubenets ◽  
S. É. Shumilin ◽  
V. V. Pustovalov
Keyword(s):  
Low Temperature ◽  
Ultrafine Grain ◽  
Micromechanical Properties ◽  
Structural Nonuniformity

Low-Temperature Spark Plasma Sintering of Yttria Ceramics with Ultrafine Grain Size

2011 ◽  
Vol 94 (10) ◽  
pp. 3301-3307 ◽  
Author(s):  
Hidehiro Yoshida ◽  
Koji Morita ◽  
Byung-Nam Kim ◽  
Keijiro Hiraga ◽  
Kohei Yamanaka ◽  
...  
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Spark Plasma Sintering ◽  
Ultrafine Grain ◽  
Plasma Sintering ◽  
Ultrafine Grain Size ◽  
Spark Plasma

Post Autofrettage Thermal Treatment and Its Effect on Re-Yielding of High Strength Pressure Vessel Steels

2009 ◽  
Author(s):  
E. Troiano ◽  
J. H. Underwood ◽  
A. P. Parker ◽  
C. Mossey
Keyword(s):  
Thermal Treatment ◽  
Low Temperature ◽  
Plastic Strain ◽  
Residual Stresses ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Lower Amount ◽  
Isotropic Hardening ◽  
Maximum Pressure ◽  
Compressive Residual Stresses

The autofrettage process of a thick walled pressure vessel involves applying tensile plastic strain at the bore of the vessel which reverses during unloading and results in favorable compressive residual stresses at the bore and prolongs the fatigue life of the component. In thick walled pressure vessels this process can be accomplished with either a hydraulic or mechanical overloading process. The Bauschinger effect, which is observed in many of the materials used in thick walled pressure vessels, is a phenomenon which results in lower compressive residual stresses than those predicted with classic ideal isotropic hardening. The phenomenon is a strong function of the amount of prior tensile plastic strain. A novel idea which involves a multiple autofrettage process has been proposed by the present authors. This process requires a low temperature post autofrettage thermal treatment which effectively returns the material to its original yield conditions without affecting its residual stress state. Details of this low temperature thermal treatment are proprietary. A subsequent second autofrettage process generates a significantly lower amount of plastic strain during the tensile re-loading and results in higher compressive residual stresses. This paper reports the details of exploratory tests involving tensile and compressive loading of a test coupon, followed by a low temperature post plastic straining thermal treatment, and subsequent re-loading in tension and compression. Finally results of a full scale Safe Maximum Pressure (SMP) test of pressure vessels are presented; these tests indicate a significant increase (11%) in SMP.

Promises of Low-Temperature Superplasticity for the Enhanced Production of Hollow Titanium Components

2016 ◽  
Vol 838-839 ◽  
pp. 610-614 ◽  
Author(s):  
Alexey Kruglov ◽  
Ramil Lutfullin ◽  
Radik Mulyukov ◽  
Minnaul Mukhametrakhimov ◽  
Oleg Rudenko ◽  
...  
Keyword(s):  
Low Temperature ◽  
Biaxial Tension ◽  
Superplastic Forming ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Processing Temperature ◽  
Hollow Structures ◽  
Enhanced Production ◽  
Ultrafine Grain Structure

Application of the conventional superplasticity (SP) allows producing the unique hollow structures. One remarkable example is the hollow titanium blade of the air engine fan produced by Rolls-Royce. However, high temperature titanium alloys processing (~ 927 °С) limits wide industrial application of the conventional SP. The solution of the mentioned issue can be found through the application of low-temperature SP. Ti-6Al-4V alloy with ultrafine grain structure at the temperature range of 600 ­ 800 °С has enough ductility resources for the superplastic forming (SPF) of the parts with the complicated shape. The formation of pores in Ti-6Al-4V alloy at uniaxial and biaxial tension at the temperature 600 °С is not observed. The effect of low-temperature SP also allows lowering pressure welding (PW) temperature essentially. Herewith, there is a possibility to produce the hollow parts by the combination of SPF and PW. The main goal is the optimization of the technological scheme and processing temperature. The use of the low-temperature SP provides high quality of hollow components such as blades.

Post-Autofrettage Thermal Treatment and Its Effect on Reyielding of High Strength Pressure Vessel Steels

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
E. Troiano ◽  
J. H. Underwood ◽  
A. P. Parker ◽  
C. Mossey
Keyword(s):  
Thermal Treatment ◽  
Low Temperature ◽  
Plastic Strain ◽  
Residual Stresses ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Lower Amount ◽  
Isotropic Hardening ◽  
Maximum Pressure ◽  
Compressive Residual Stresses

The autofrettage process of a thick walled pressure vessel involves applying tensile plastic strain at the bore of the vessel, which reverses during unloading and results in favorable compressive residual stresses at the bore and prolongs the fatigue life of the component. In thick walled pressure vessels this process can be accomplished with either a hydraulic or mechanical overloading process. The Bauschinger effect, which is observed in many of the materials used in thick walled pressure vessels, is a phenomenon, which results in lower compressive residual stresses than those predicted with classic ideal isotropic hardening. The phenomenon is a strong function of the amount of prior tensile plastic strain. A novel idea, which involves a multiple autofrettage processes, has been proposed by the present authors. This process requires a low temperature post-autofrettage thermal treatment, which effectively returns the material to its original yield conditions with minimal effect on its residual stress state. Details of this low temperature thermal treatment are proprietary. A subsequent second autofrettage process generates a significantly lower amount of plastic strain during the tensile reloading and results in higher compressive residual stresses. This paper reports the details of the exploratory tests involving tensile and compressive loading of a test coupon, followed by a low temperature post-plastic straining thermal treatment, and subsequent reloading in tension and compression. Finally results of a full scale safe maximum pressure (SMP) test of pressure vessels are presented; these tests indicate a significant increase (11%) in SMP.

Measurements of Strain Induced Resistivity by the Eddy-Current Decay Method

1988 ◽  
Vol 142 ◽  
Author(s):  
K. Theodore Hartwig
Keyword(s):  
Electrical Resistivity ◽  
Low Temperature ◽  
Plastic Strain ◽  
Eddy Current ◽  
Pure Aluminum ◽  
Bulk Metal ◽  
Resistivity Measurements ◽  
Current Decay ◽  
Characterization Studies

AbstractThe eddy-current decay method developed by Bean for electrical resistivity measurements is well-suited for bulk metal characterization studies. The technique can be applied to investigations of low temperature plastic strain in pure aluminum.

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