Haynes 188 Alloy

C Carbon
Mn Manganese
1.25 max
Si Silicon
Cr Chromium
Co Cobalt
39.0 max
Ni Nickel
Fe Iron
3.0 max
W Tungsten
La Lanthanum

General characteristics of Haynes 188 Alloy

Alloy 188 is a cobalt-nickel-chromium tungsten alloy that combines excellent high-temperature strength with very good oxidation resistance to approximately 2000ºF (1095ºC).


The alloy is used in military and civil gas turbine engines and in many industrial applications.


Stock should be soaked for ½ hour per inch of section thickness at 2150ºF (1175ºC). The material may be forged down to 1800ºF (980ºC), preferably using heavier reductions to minimize grain growth.

Heat treatment

This alloy is normally supplied from the mill in the solution-annealed condition, with a microstructure of randomly dispersed carbide with no harmful grain-boundary precipitation.
Solution annealing during subsequent processing is carried out at 2125/2175ºF (1165/1190ºC).


This alloy is moderate to difficult to machine, but may be machined by most conventional methods providing the equipment is overpowered and the work piece and tool are held rigidly.
Sharp, carbide-tipped tools are recommended, as are heavy, positive feeds and adequate lubrication.


The weldability of this alloy is similar in many ways to that of austenitic stainless steels. The alloy is commonly welded by the gas-tungsten-arc, gas-metal-arc and submerged- metal-arc processes. Oxyacetylene welding is not recommended due to the danger of carbon pickup in the weld.
The alloy tends to demonstrate sluggish welding and shallow penetration characteristics compared to those of austenitic stainless steels, hence the need for careful joint design and weld bead placement.

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