Jul 5 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Annealing
Forging
Hot Working
Cold Working
Applications
Introduction
The mechanical properties of commercially pure titanium alloys are influenced by the presence of small amounts of oxygen and iron. Grade 1 unalloyed Ti ("Pure") 35A alloy contains the lowest oxygen and iron levels, thereby making this grade the most formable of material. This alloy has the highest purity.
Grade 1 is known to possess excellent resistance to mildly reducing to highly oxidizing media with or without chlorides, high weldability, good impact toughness, excellent room-temperature ductility. It is nonmagnetic.
The following sections will discuss in detail about grade 1 unalloyed Ti ("Pure") 35A alloy.
Chemical Composition
The chemical composition of grade 1 unalloyed Ti ("Pure") 35A alloy is outlined in the following table.
|
Element |
Content (%) |
|
Titanium, Ti |
≥ 99.1 |
|
Iron, Fe |
≤ 0.20 |
|
Oxygen, O |
≤ 0.18 |
|
Carbon, C |
≤ 0.080 |
|
Nitrogen, N |
≤ 0.030 |
|
Hydrogen, H |
≤ 0.015 |
Physical Properties
The physical properties of grade 1 unalloyed Ti ("Pure") 35A alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
4.51 g/cm3 |
0.163 lb/in3 |
|
Melting point |
1670°C |
3038°F |
Mechanical Properties
The following table shows mechanical properties of grade 1 unalloyed Ti ("Pure") 35A alloy.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
345 MPa |
50000 psi |
|
Yield strength |
220 MPa |
31900 psi |
|
Poisson's ratio |
0.34-0.40 |
0.34-0.40 |
|
Elastic modulus |
105 - 120 GPa |
15200 - 17400 ksi |
|
Elongation at break |
35% |
35% |
|
Hardness (HV) |
115 |
115 |
Thermal Properties
The thermal properties of grade 1 unalloyed Ti ("Pure") 35A are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@0.000-100°C/32-212°F) |
8.60 µm/m°C |
4.78 µin/in°F |
|
Thermal conductivity |
21.97 W/mK |
152.5 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to grade 1 unalloyed Ti ("Pure") 35A alloy are as follows:
|
ASTM B337 |
ASTM B338 |
ASTM B381 |
ASTM F67 |
ASTM F67 (1) |
|
ASTM B265 |
ASTM B348 |
ASTM F467 (1) |
ASTM F468 |
DIN 3.7025 |
|
DMS 1536 |
MIL T-81556 |
MIL T-81915 |
|
|
Fabrication and Heat Treatment
Machinability
Grade 1 unalloyed Ti ("Pure") 35A alloy is hard to machine but can be successfully done using slow speeds, high coolant flow, and high feed rates. Tooling should be performed using tungsten carbide designations C1-C4 or cobalt type high speed tools.
Forming
Grade 1 unalloyed Ti ("Pure") 35A alloy can be hot or cold formed using power brake, hydropress, stretch or drop hammer methods.
Welding
Welding of grade 1 unalloyed Ti ("Pure") 35A alloy is rated as good.
Annealing
Annealing of this material can be performed by heating to 704°C (1299°F), and then held for 2 h, which should be followed by air cooling. In case intermediate stress relieving is required, the material has to be heated to 482°C (900°F) for 45 min.
Forging
Rough forging can be performed at 871°C (1600°F) and completed at 788-843°C (1450-1550 °F).
Hot Working
Hot working enhances the overall ductility of the material.
Cold Working
Cold working features of this material is same as that of a moderately tempered austenitic stainless steel. Post-work annealing is recommended to re-attain favorable performance properties.
Applications
Grade 1 unalloyed Ti ("Pure") 35A alloy is used in the following application areas:
-
Navy ship components
-
Food processing/pharmaceutical
-
Chemical processing equipment
-
Anode/cathode/cell components
-
Hydrocarbon refining/processing
-
Pulp/paper bleaching/washing equipment
-
Desalination, brine concentration/evaporation
-
Hydrometallurgical extraction/electrowinning
-
Medical implants/devices, surgical instruments
-
Consumer products such as watches and eye glass frames