Hydrogen Absorption in Cathodically Polarized Titanium Alloys

2002 ◽  
Author(s):  
Marion Seiersten ◽  
Tor Gunnar Eggen ◽  
Liv Lunde ◽  
Trond Rogne
Keyword(s):  
Titanium Alloys ◽  
Hydrogen Absorption ◽  
Cold Working ◽  
Alloy Composition ◽  
Potential Temperature ◽  
Hydrogen Uptake ◽  
Natural Seawater ◽  
Thermal Gradients ◽  
Test Program ◽  
Permanent Strain

Cathodic polarisation may cause hydrogen absorption and embrittlement of titanium alloys. There is no need to protect titanium in seawater, but polarisation is inevitable when titanium components are connected to steel that is cathodically protected. The risk of hydrogen embrittlement of risers and other heavily loaded components rouse a need to quantify the amount of hydrogen that titanium alloys may absorb as a function of alloy composition, polarisation potential, temperature, cold working and time. The test program included Ti-3Al-2.5V and Ti-6Al-4V alloys that are candidate materials for risers. The hydrogen uptake was measured over a 3 years period in natural seawater. The results show that titanium absorbs hydrogen when it is polarised to potentials less than −0.8V vs. Ag/AgCl in seawater, but the absorption rate decreased with time. The maximum hydrogen loading measured after three years exposure at −1.04 V vs. Ag/AgCl was 150 ppm. A calcareous deposit built up on all surfaces and limited the hydrogen evolution and thereby the hydrogen uptake. Ti-3Al-2.5V alloys picked up less hydrogen than Ti-6Al-4V alloys, and palladium or ruthenium enhanced hydrogen uptake to some extent. Welding or cold working did not influence hydrogen uptake of the alloys included in the tests. Temperature had little effect, and thermal gradients in the titanium materials had no measurable influence. The effect of hydrogen on the mechanical properties of the alloys was not studied in detail in these experiments, but most specimens were tensioned C-rings with permanent strain. Neither of these developed cracks or other signs of embrittlement during the tests.

Fracture Toughness of Powder Metallurgy and Ingot Titanium Alloys – A Review

2013 ◽  
Vol 551 ◽  
pp. 143-160 ◽  
Author(s):  
Ajit Pal Singh ◽  
Brian Gabbitas ◽  
De Liang Zhang
Keyword(s):  
Fracture Toughness ◽  
Powder Metallurgy ◽  
Titanium Alloys ◽  
Alloy Composition ◽  
Low Cost ◽  
Ingot Metallurgy ◽  
Metal Powders ◽  
Critical Factors ◽  
Microstructural Characteristics ◽  
High Degree

Powder metallurgy (PM) is potentially capable of producing homogeneous titanium alloys at relative low cost compared to ingot metallurgy (IM). There are many established PM methods for consolidating metal powders to near net shapes with a high degree of freedom in alloy composition and resulting microstructural characteristics. The mechanical properties of titanium and its alloys processed using a powder metallurgical route have been studied in great detail; one major concern is that ductility and toughness of materials produced by a PM route are often lower than those of corresponding IM materials. The aim of this paper is to review the fracture toughness of both PM and IM titanium alloys. The effects of critical factors such as interstitial impurities, microstructural features and heat treatment on fracture toughness are also discussed

Thermomechanical Fatigue Behavior of Bare and Coated CMSX-4

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
T. Coppola ◽  
S. Riscifuli ◽  
O. Tassa ◽  
G. Pasquero
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Thermomechanical Fatigue ◽  
Tensile Creep ◽  
Thermal Gradients ◽  
Test Program ◽  
Complete Set ◽  
Comparison Of The Results ◽  
Very High

Highly cooled turbine blades undergo very high thermal gradients during rapid engine idle-max-idle cycling. Traditional isothermal fatigue data are often insufficient for predicting service lives. A complete set of high temperature tests, in the range of 750–1050°C, was performed on single crystal alloy CMSX-4. The test program comprised tensile, creep, low cycle fatigue, and thermomechanical fatigue (TMF) tests. In particular the cycle time for TMF was 3 min, aiming to simulate the real high-power transient conditions in aircraft engines. Clockwise and counterclockwise diamond cycle types were applied on bare and coated specimens to investigate their influence on the fatigue limit. The comparison of the results obtained with the available ones from open literature is discussed.

Effect of alloy composition on the volume fraction of beta phase in duplex titanium alloys

1993 ◽  
Vol 29 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Hyuck Mo Lee ◽  
Jeong-Ryong Soh ◽  
Zin-Hyoung Lee ◽  
Yong-Suk Kim
Keyword(s):  
Titanium Alloys ◽  
Alloy Composition ◽  
Volume Fraction ◽  
Beta Phase

scholarly journals A Numerical Study of Cirrus Bands and Low Static-stability Layers associated with Tropical Cyclone Outflow

2021 ◽  
Author(s):  
Masayuki Kawashima
Keyword(s):  
Numerical Study ◽  
Potential Temperature ◽  
Outer Region ◽  
Static Stability ◽  
Core Region ◽  
Thin Layers ◽  
Vertical Shear ◽  
Thermal Gradients ◽  
Shallow Convection ◽  
The Core

AbstractProminent cirrus cloud banding occurred episodically within a northern cirrus canopy of Typhoon Talim (2017) during its recurvature. The generation mechanisms of the cirrus bands and low static-stability layers that support the bands are investigated using a numerical simulation with the Advanced Research Weather Research and Forecasting Model. Inspection of model output reveals that thin layers of near-neutral to weakly unstable static stability are persistently present in the upper and lower parts of the upper-level outflow, and shallow convection aligned along the vertical shear vector is prevalent in these layers. The cirrus banding occurs as the lowered outflow from the weakening storm ascends slantwise over a midlatitude baroclinic zone, and updrafts of the preexisting shallow convection in the upper part of the outflow layer become saturated. It is shown that the strong outflow resulting from violation of gradient-wind balance in the core region, by itself, creates the low static-stability layers. Analyses of potential temperature and static stability budgets show that the low static-stability layers are created mainly by the differential radial advection of radial thermal gradients on the vertical edges of the outflow. The radial thermal gradients occur in response to the outward air parcel acceleration in the core region and deceleration in the outer region, which, by inducing compensating vertical mass transport into and out of the outflow, act to tilt the isentropes within the shear layers. The effects of environmental flow and cloud radiative forcing on the cirrus banding are also addressed.

HYDROGEN ABSORPTION IN ALUMINIUM - MAGNESIUM - TITANIUM ALLOYS

1982 ◽  
pp. 437-443
Author(s):  
D. Lupu ◽  
A. Biris ◽  
R.V. Bucur ◽  
E. Indrea ◽  
M. Bogdan
Keyword(s):  
Titanium Alloys ◽  
Hydrogen Absorption

scholarly journals Effect of Sign-Alternating Cyclic Polarisation and Hydrogen Uptake on the Localised Corrosion of X70 Pipeline Steel in Near-Neutral Solutions

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 245
Author(s):  
Alevtina Rybkina ◽  
Natalia Gladkikh ◽  
Andrey Marshakov ◽  
Maxim Petrunin ◽  
Andrei Nazarov
Keyword(s):  
Corrosion Rate ◽  
Hydrogen Absorption ◽  
Aqueous Electrolyte ◽  
Pipeline Steel ◽  
Hydrogen Uptake ◽  
Half Cycle ◽  
X70 Pipeline Steel ◽  
Quantitative Indicator ◽  
Bicarbonate Ions ◽  
Corrosion Of Steel

The effect of sign-alternating cycling polarisation (SACP) on the localised corrosion of X70pipeline steel in solutions of various compositions was studied. Localised corrosion of steel at anodic potentials was accelerated with an increase in the duration of the cathodic half-cycle, in the presence of a promoter of hydrogen absorption in aqueous electrolyte, and with an increase in the concentrations of chloride and bicarbonate ions. It was pointed out that the corrosion rate is determined by the amount of hydrogen absorbed by the steel. A quantitative indicator to determine the intensity of localised corrosion under SACP was suggested.

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