Grade 28 Ti 3Al 2.5V 0.1Ru Alloy (UNS R56323)

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.

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