인코넬 스프링(INCONEL 718) 데이타

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Type Analysis

Element	Min	Max
Carbon	--	0.08
Manganese	--	0.35
Silicon	--	0.35
Phosphorus	--	0.015
Sulfur	--	0.015
Nickel + Cobalt	50.0	55.0
Chromium	17.0	21.0
Cobalt	--	1.00
Iron	Balance
Aluminum	0.35	0.80
Molybdenum	2.80	3.30
Titanium	0.65	1.15
Boron	0.001	0.006
Copper	--	0.15
Cb + Ta	4.75	5.50

Description

Alloy 718 is a precipitation hardenable nickel-base alloy designed to display exceptionally high yield, tensile and creep-rupture properties at temperatures up to 1300°F. The sluggish age-hardening response of alloy 718 permits annealing and welding without spontaneous hardening during heating and cooling. This alloy has excellent weldability when compared to the nickel-base superalloys hardened by aluminum and titanium. This alloy has been used for jet engine and high-speed airframe parts such as wheels, buckets, spacers, and high temperature bolts and fasteners.

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Physical Constants

Density                                                                                  Electrical resistivity 
   lb/cu in .............................. 0.293                                       ohms-cir mil/ft ................................ 728
   kg/cu m .............................. 8220                                       microhm-mm ................................. 1210 
Melting Range
  °F ................................ 2200-2450
  °C .................................1210/1344

Modulus of Elasticity (E)

Temperature		psi x 10(6)	MPa x 10(3)
°F	°C
70 200 400 600 800 1000 1200 1400 1600 1750	21 93 204 316 427 538 649 760 871 954	29.6 29.2 28.8 27.6 26.5 25.5 24.5 23.1 18.1 11.1	2.08 2.05 2.02 1.94 1.86 1.79 1.72 1.62 1.27 0.78

Coefficient of Thermal Expansion

Temperature Range		10(-6)/°F	10(-6)/°C
77°F to	25°C to
200 400 600 800 1000 1200 1400	93 204 316 427 538 649 760	7.1 7.5 7.7 7.9 8.0 8.4 8.9	12.8 13.5 13.9 14.2 14.4 15.1 16.0

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Heat Treatment

The following heat treatment should be used to obtain the best combination of tensile properties and stress rupture properties:
1 hr 1750°F to 1800°F (954 to 982°C) air cool + 8hr 1325°F (718°C) cool 100°F /hr to 1150°F (56 °C/hr to 621°C), hold 8 hrs and air cool.
To obtain the best room temperature and cryogenic tensile properties, the following hetat treatment should be used: 
1 to 2 hr 1950°F (1066°C), air cool + 8 hr 1325°F (718°C) cool 100°F/hr to 1150°F (56°C/hr to 621°C), hold 8 hr and air cool.

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Workability

Hot Working
Hot-working is carried out using a 2050°F (1121°C) maximum furnace temperature. Hot-cold working in the range 1700/1850°F (927/1010°C) will improve the strength of the forging if the service temperature is below about 1100°F (593°C). Prolonged soaking at the forging temperature is not desirable. The material should be given uniform reductions to avoid the formation of duplex grain structures.

Machining
The alloy can be readily machined in either the annealed or the age-hardened condition. The age-hardened condition gives better chip action on chip breaker tools and produces a better finish. The annealed condition will give a slightly longer tool life.

Welding
Alloy 718 can be welded in either the annealed or the age condition. Welding in the aged condition will cause the formation of a softened heat-affected zone.

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Typical Mechanical Properties

Elevated Temperature Tensile Tests
1/2" bar stock

Test Temperature		0.2% Yield Strength		Tensile Strength		% Elongation 2"
°F	°C	ksi	MPa	ksi	MPa
200 400 600 800 1000 1200 1400	93 204 316 427 538 649 760	170 163 159 156 155 149 110	1172 1124 1096 1076 1069 1027 758	204 198 195 191 185 168 110	1407 1365 1344 1317 1276 1158 758	21.0 20.0 20.0 19.0 18.0 19.0 27.0

Heat Treatment: 1 hr - 1800°F, air cool + 8 hr-1325°F, cool 100°F/hr to 1150°F, hold 8 hr, air cool.

Stress Rupture Data

Test Temperature		Stress for Rupture
°F	°C	100 Hours				1000 Hours
		Smooth		Notch		Smooth		Notch
		ksi	MPa	ksi	MPa	ksi	MPa	ksi	MPa
1100 1200 1300 1400	593 649 704 760	170 110 75 44	1172 758 517 303	220 195 130 63	1517 1344 896 434	130 85 55 25	896 586 379 172	205 170 80 35	1416 1172 552 241

Heat Treatment: 1 hr - 1850°F, air cool + 8 hr - 1325°F, furnace cool to 100°F/hr to 1150°F, hold 8 hr, air cool.