Super Alloy INCOLOY Alloy 25-6MO (UNS N08926)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication
     Machinability
     Welding
     Hot working
     Cold Working
     Annealing
Applications

Introduction

INCOLOY alloys belong to the category of super-austenitic stainless steel alloys. Nickel, chromium and iron are the principal constituents of this alloy. By adding different additives this alloy can be made to resist different chemical reagents. Good strength and resistance to corrosion are characteristics of these alloys.

Additives such as molybdenum and nitrogen are added to the alloy in order to increase its resistance to pitting, crevice corrosion and thermal stability. The nickel and chromium content extend the corrosion resistance of this alloy over a wide range of environments like non-oxidizing acids, aqueous, caustic chlorides, halides and pulp-mill bleaches. This alloy is available in the form of bars, billets, sheets, round, plate, strips and wire.

This datasheet will look into the chemical composition, properties and applications of INCOLOY 25-6MO.

Chemical Composition

The chemical composition of INCOLOY alloy 25-6MO is given in the following table.

Element Content (%)
Iron, Fe 47.3
Nickel, Ni 24-26
Chromium, Cr 19-21
Molybdenum, Mo 6-7
Manganese, Mn ≤2
Others Remainder

Physical Properties

The following table discusses the physical properties of INCOLOY alloy 25-6MO.

Properties Metric Imperial
Density 8.03 gm/cm3 0.290 lb/in3

Mechanical Properties

The mechanical properties of INCOLOY alloy 25-6MO are tabulated below.

Properties Metric Imperial
Tensile strength(annealed) 689 MPa 100 ksi
Yield strength(annealed) 331 MPa 48 ksi
Elongation at Break( in 2 in 50 mm) ≥42% ≥42%
Hardness, Rockwell B 86 86
Modulus of Elasticity 188 GPa 27300 ksi
Poissons Ratio 0.33 0.33

Other Designations

Some of the designations used to denote INCOLOY alloy 25-6MO are listed below:-

  • UNS N08926

Fabrication

Machinability

Machining characteristics of this INCOLOY alloy 25-6MO is similar to that of other austenitic alloys.

Machining of INCOLOY alloy 25-6MO should be done at a slightly lower speed when compared stainless steel using rigid tooling and optimum lubrication and cooling.

Welding

INCOLOY alloy 25-6MO can be welded by gas metal arc welding, gas tungsten arc welding, shielded arc welding, plasma arc welding and submerged metal arc welding. The filler metal and electrodes are usually made of INCONEL alloy.

Hot working

INCOLOY alloy 25-6MO can be hot worked at temperature ranges of 980-1150°C (1800-2100°F).

Cold Working

Cold rolling may be done on the alloy after annealing.

Annealing

INCOLOY alloy 25-6MO should be annealed at temperatures greater than 1175°C (2150°F).

Applications

The INCOLOY alloy 25-6MO is used in the following applications:

  • Chemical and food processing
  • Paper bleaching plants
  • Marine and offshore platform equipment
  • Air pollution control systems
  • Salt plant evaporators
  • Condenser tubes, service water pipes and feed water heaters.

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