Super Alloy Alumel™

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Heat Treatment
     Forging
     Hot Working
     Cold Working
     Annealing
Applications

Introduction

Super alloys or high performance alloys have the ability to function at high temperatures and under mechanical stress. They have good creep and oxidation resistance, and are available in different forms. Solid-solution hardening, work hardening, and precipitation hardening are performed in order to enhance their strength. They are categorized into three groups such as cobalt-based, nickel-based, and iron-based super alloys.

Alumel™ is a high nickel alloy. The datasheet given below will discuss about Alumel™.

Chemical Composition

The chemical composition of Alumel™ is outlined in the following table.

Elements Content (%)
Nickel, Ni 95
Aluminum, Al 2
Manganese, Mn 2

Physical Properties

The physical properties of thermocouple wire type K – Std Alumel™ are given in the following table.

Properties Metric Imperial
Density 8.61 g/cm³ 0.311 lb/in³
Melting point 1399°C 2550°F

Mechanical Properties

The following table shows the mechanical properties of Alumel™.

Properties Metric Imperial
Tensile strength at break (annealed) 586 MPa 85000 psi
Tensile strength at break (stress relieved) 1030 MPa 150000 psi
Tensile strength at break (hard) 1170 MPa 170000 psi

Thermal Properties

The thermal properties of Alumel™ are displayed in the following table.

Properties Metric Imperial
Thermal expansion co-efficient (@ 20°C/68°F) 12 µm/m°C 6.67 µin/in°F
Thermal conductivity 29.7 W/mK 206 BTU in/hr.ft².°F

Fabrication and Heat Treatment

Machinability

Alumel™ has good machinability.

Forming

Alumel™ has good formability.

Welding

Alumel™ can be welded using conventional methods.

Heat Treatment

Alumel™ is heat treated by annealing at 1066°C (1950°F) followed by cooling.

Forging

Alumel™ is forged at 1149°C (2100°F).

Hot Working

Alumel™ is hot worked at 705 to 1038°C (1300 to 1900°F).

Cold Working

Alumel™ has good cold working capacity.

Annealing

Alumel™ is annealed at 1066°C (1950°F) followed by cooling.

Applications

Alumel™ can be used with a chromel alloy to develop a thermocouple.

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