Jul 5 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Heat treatment
Annealing
Aging
Applications
Introduction
Grade 28 Ti-3Al-2.5V-0.1Ru alloy is a ruthenium-enhanced version of grade Ti-3Al-2.5V with similar physical and mechanical properties. Ruthenium provides this alloy with improved corrosion resistance. This alloy provides high resistance to dilute reducing acids and crevice corrosion in hot halide (brine) solution. It has been approved for use in sour service under the NACE MR-01-75 Standard.
The following sections will discuss in detail about grade 28 Ti-3Al-2.5V-0.1Ru alloy.
Chemical Composition
The chemical composition of grade 28 Ti-3Al-2.5V-0.1Ru alloy is outlined in the following table.
|
Element |
Content (%) |
|
Titanium, Ti |
92.435 - 95.42 |
|
Aluminum, Al |
2.5 - 3.5 |
|
Vanadium, V |
2-3 |
|
Ruthenium, Ru |
0.080 - 0.14 |
|
Iron, Fe |
≤ 0.25 |
|
Oxygen, O |
≤ 0.15 |
|
Carbon, C |
≤ 0.080 |
|
Nitrogen, N |
≤ 0.030 |
|
Hydrogen, H |
≤ 0.015 |
|
Other, each |
≤ 0.10 |
|
Other, total |
≤ 0.40 |
Physical Properties
The physical properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
4.48 g/cm3 |
0.161 lb/in3 |
|
Melting point |
1700°C |
3092°F |
Mechanical Properties
The following table shows mechanical properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
620 MPa |
90 ksi |
|
Yield strength |
483 MPa |
70 ksi |
|
Poisson's ratio |
0.34 |
0.34 |
|
Elastic modulus |
107 GPa |
15519 ksi |
|
Hardness (HV) |
260-320 |
260-320 |
Thermal Properties
The thermal properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal conductivity |
7.9 W/mK |
54.7 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to grade 28 Ti-3Al-2.5V-0.1Ru alloy are as follows:
-
ASTM B265
-
ASTM B337
-
ASTM B338
-
ASTM B381
-
ASTM B861
-
ASTM B862
Fabrication and Heat Treatment
Heat treatment
Grade 28 Ti-3Al-2.5V-0.1Ru alloy can be solution treated at 870-925°C (1598-1697°F) for 15-20 h and then water quenched.
Annealing
Annealing of this material can be performed by heating to 595-760°C (1103-1400°F) for 1-3 h and then air-cooled.
Aging
Aging of grade 28 Ti-3Al-2.5V-0.1Ru alloy can be performed at 480-510°C (896-950°F) for 2-8 h and then air-cooled.
Applications
Grade 28 Ti-3Al-2.5V-0.1Ru alloy finds use in:
-
Seawater applications
-
High crevice corrosion temperature environment.