Super Alloy Nimonic 901™ (UNS N09901)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Cold Working
Applications

Introduction

Super alloys are also known as high performance alloys. They contain many elements in a variety of combinations so as to achieve the desired result. These alloys can function in environments with very high temperatures and severe mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance.

Strengthening of super alloys is performed by solid-solution hardening, work hardening, and precipitation hardening methods.

Nimonic 901™ is a nickel-chromium-molybdenum alloy that is precipitation hardened using heat treatment. This alloy is preferred for use in oxidizing environments with temperatures of about 593°C (1100°F).

The following datasheet will provide more details about Nimonic 901™.

Chemical Composition

The following table shows the chemical composition of Nimonic 901™.

Element Content (%)
Nickel, Ni 40-45
Iron, Fe 33
Chromium, Cr 11-14
Molybdenum, Mo 5.0 - 6.50
Titanium, Ti 2.80-3.10
Cobalt, Co 1
Manganese, Mn 0.50
Copper, Cu 0.50
Silicon, Si 0.40
Aluminum, Al 0.35
Carbon, C 0.10
Sulfur, S 0.030

Physical Properties

The physical properties of Nimonic 901™ are outlined in the following table.

Properties Metric Imperial
Density 8.14 g/cm³ 0.294 lb/in³
Melting point 1280-1345°C 2340-2453°F

Mechanical Properties

The mechanical properties of Nimonic 901™ are provided below.

Properties Metric Imperial
Tensile strength (precipitation hardened, value at room temperature) 1200 MPa 174000 psi
Yield strength (@strain 0.200%, precipitation hardened, value at room temperature) 875 MPa 127000 psi
Elongation at break (precipitation hardened) 15% 15%

Thermal Properties

The thermal properties of Nimonic 901™ are given below.

Properties Metric Imperial
Thermal expansion co-efficient (@21-100°C/69.8-212°F) 13.5 µm/m°C 7.50 µin/in°F

Other Designations

Equivalent material to Nimonic 901™ is DIN 2.4662.

Fabrication and Heat Treatment

Machinability

Traditional machining methods that are used for iron-based alloys can be used for Nimonic 901™. During high speed operations such as grinding, turning, or milling, water-based coolants are preferred. The use of heavy lubricants while drilling, tapping, broaching or boring is recommended. In cases where turning with a continuous cut is performed, carbide tools are suitable.

Forming

Nimonic 901™ has good ductility and can be easily formed using all the conventional methods.

Welding

Nimonic 901™ can be welded using the traditional welding methods. Some of the commonly used methods are gas-tungsten arc welding, shielded metal-arc welding, gas metal-arc welding and submerged-arc welding. It is recommended that matching alloy filler metal should be used. Before the welding process begins, the surface to be welded should be cleaned and should be free from oil, paint or crayon stains.

Cold Working

Cold working can be performed using standard tooling. To minimize galling and provide a neat finish, soft die materials containing bronze and zinc alloys are recommended. However, the life of the die is short.

Applications

Nimonic 901™ is mainly used in gas turbines for turbine shafts or discs.

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