Grade 4 Unalloyed Ti ("Pure") 75A (UNS 50700)

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

Commercially pure titanium alloys are available in many forms. The content of oxygen and iron influences their mechanical properties. Each commercial grade is designed to meet the needs for different applications.

Grade 4 Unalloyed Ti ("Pure") 75A alloy is the highest strength of all the unalloyed grades. It is known to possess good ductility and medium formability. Good strength to weight ratio is well maintained at moderate temperatures. At low temperatures, this alloy also has good impact properties.

The following sections will discuss in detail about grade 4 Unalloyed Ti ("Pure") 75A alloy.

Chemical Composition

The chemical composition of grade 4 Unalloyed Ti ("Pure") 75A alloy is outlined in the following table.

Element Content (%)
Titanium, Ti ≥ 98.6
Iron, Fe ≤ 0.50
Oxygen, O ≤ 0.40
Carbon, C ≤ 0.080
Nitrogen, N ≤ 0.050
Hydrogen, H ≤ 0.015

Physical Properties

The physical properties of grade 4 Unalloyed Ti ("Pure") 75A alloy are tabulated below.

Properties Metric Imperial
Density 4.51 g/cm3 0.163 lb/in3
Melting point 1660°C 3020°F

Mechanical Properties

The following table shows mechanical properties of grade 4 Unalloyed Ti ("Pure") 75A alloy.

Properties Metric Imperial
Tensile strength 680 MPa 98600 psi
Yield strength 560 MPa 81200 psi
Poisson's ratio 0.34-0.40 0.34-0.40
Elastic modulus 105 - 120 GPa 15200 - 17400 ksi
Elongation at break 23% 23%
Hardness (HV) 250 250

Thermal Properties

The thermal properties of grade 4 Unalloyed Ti ("Pure") 75A 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 16.95 W/mK 117.6 BTU in/hr.ft².°F

Other Designations

Equivalent materials to grade 4 Unalloyed Ti ("Pure") 75A alloy are as follows:

ASTM B348 ASTM F67 MIL T-9046 MIL T-9047
ASTM B265 ASTM F468 (4) MIL T-81556 ASTM B381
AMS 4921 ASTM F467 (Ti-4) MIL F-83142 ASTM F67 (4)
AMS 4901







Fabrication and Heat Treatment

Machinability

Grade 4 Unalloyed Ti ("Pure") 75A 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 4 Unalloyed Ti ("Pure") 75A alloy can be hot or cold formed using power brake, hydropress, stretch or drop hammer methods.

Welding

Weldability of grade 4 Unalloyed Ti ("Pure") 75A 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 482-538°C (900-100-°F) for 45 min.

Forging

Rough forging can be performed at 935°C (1715°F) and completed at 843°C (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 4 Unalloyed Ti ("Pure") 75A alloy is used in the following:

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit