Grade 1 Unalloyed Ti ("Pure") 35A (UNS R50250)

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

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