Alloy 188 is a cobalt base superalloy with a unique combination of high temperature strength and oxidation resistance, along with adequate ductility after prolonged exposure to the 1400-1600°F temperature range.
Cobalt alloys have an inherent advantage over the nickel base grades in high temperature creep. Alloy 188 is solid solution strengthened by a 14% tungsten addition, and further by M6C and M23C6 carbides. Alloy 188 is readily fabricated, being welded by both manual and automatic methods including electron beam, gas tungsten arc and resistance welding.
Chemistry

	Cr	Ni	Co	W	La	B	C	Fe	Mn	Si	P	S
MIN	20.0	20.0	-	13.0	0.02	-	0.05	-	-	0.2	-	-
MAX	24.0	24.0	Balance	16.0	0.12	0.015	0.015	3.0	1.25	0.5	0.02	0.015

Specifications
AMS 5608, AMS 5801
EN 2.4683
PWA 1042
UNS R30188, Werkstoff 2.4683
Inventory
188 Coil, 188 Sheet, 188 Weld Wire
Common Trade Names
Alloy 188
Features
• Strength and oxidation resistant to 2000°F
• Good post-aging ductility
• Resistant to sulfate deposit hot corrosion
Applications
• Gas turbine engine combustor cans, spray bars, flame-holders and afterburner liners
Physical Properties
Density: 0.324 lb/in3
Melting Range: 2375 -2570°F

Temperature, °F	70	800	1000	1200	1400	1600	1800
Coefficient* of Thermal Expansion, in/in°F x 10-6	-	7.8	8.2	8.6	9.0	9.4	9.9
Thermal Conductivity Btu • ft/ft2 • hr • °F	-	10.4	11.5	12.7	13.9	14.5	15.8
Modulus of Elasticity Dynamic, psi x 106	34	29	28	26	25	24	22

* 70°F to indicated temperature.
Mechanical Properties
Representative Tensile Properties, Sheet

Temperature, °F	70	1200	1400	1600	1800	2000
Ultimate Tensile Strength, ksi	137	103	90	60	35	19
0.2% Yield Strength, ksi	67	40	39	36	19	9
Elongation, %	53	59	63	64	59	32

Typical Stress-Rupture Strength

Temperature, °F	1400	1500	1600	1700	1800
100 Hours, ksi	32	22	14	9	5
1,000 Hours, ksi	23	15	9	6	2

188 is a Trademark of Haynes International