UDIMET Alloy 188 (UNS R10388)

Topics Covered

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

Introduction

UDIMET alloys are categorised as super alloys. Super alloys are high performance alloys that have cobalt, iron or nickel as the base metals. UDIMET alloys are capable of functioning under elevated temperatures and high mechanical stress. These alloys can be hardened by solid solution hardening, work hardening or precipitation hardening. Some of the commercial types of UDIMET alloys are UDIMET alloy 188, 250, 520, 720, D-979, R41 and L-605.

UDIMET alloy 188 is a cobalt-based alloy that is characterised by high-temperature strength and good resistance to oxidation at elevated temperatures. The alloy is doped with chromium and small amounts of lanthanum. The alloy is also resistant to sulfidation. Some of the other characteristics of the alloy are metallurgical stability, good ductility, good weldability and fabricability.

This datasheet will look into the chemical composition, properties and applications of UDIMET alloy 188.

Chemical Composition

The chemical composition of UDIMET alloy 188 is given in the following table.

Element Content (%)
Cobalt, Co 30.9765-46.73
Nickel, Ni 20-24
Chromium, Cr 20-24
Tungsten, W 13-16
Lanthanum, La 0.020-0.12
Others Remainder

Physical Properties

The following table discusses the physical properties of UDIMET alloy 188.

Properties Metric Imperial
Density 9.14 gm/cm3 0.330 lb/in3

Mechanical Properties

The mechanical properties of UDIMET alloy 188 are tabulated below.

Properties Metric Imperial
Tensile strength 963 MPa 140 ksi
Yield strength 446 MPa 64.7 ksi
Elongation at Break 55% 55%

Other Designations

Some of the other designations that are used to denote UDIMET alloy 188 are as below:

  • UNS R10388
  • AMS 5608
  • AMS 5772

Fabrication

Machinability

The conventional machining techniques can be used on this alloy.

Welding

UDIMET alloy 188 can be welded using common techniques, using a matching filler metal. Welding methods such as shielded metal arc, gas tungsten arc and gas metal arc welding are best suited for UDIMET alloy 188.

Cold working

Cold working may be done on the alloy. Cold working techniques such as bending, deep drawing and spinning may be performed easily on the alloy.

Annealing

UDIMET alloy 188 can be normally annealed at 1177°C (2150°F) and rapidly cooled in air or by water-quenching.

Applications

The UDIMET alloy 188 is used in the following applications:

  • Gas turbine parts such as combustors, flame holders
  • Turbine transition ducts and liners.

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