Inconel X-750

INCONEL X-750 TECHNICAL DATA

Type Analysis

Element Min Max
Carbon 0.08
Manganese 0.30
Silicon 0.50
Sulfur 0.01
Nickel + Cobalt 70.0 min
Chromium 14.0 17.0
Iron 5.00 9.00
Aluminum 0.40 1.00
Titanium 2.25 2.70
Copper 0.50
Cb + Ta 0.70 1.20

Description

Alloy X-750 is a precipitation-hardenable alloy which has been used in applications such as high temperature structural members for gas turbines, jet engine parts, nuclear power plant applications, heat-treating fixtures, forming tools, and extrusion dies. The alloy is highly resistant to chemical corrosion and oxidation and has high stress-rupture strength and low creep rates under high stresses at temperatures up to 1500°F (816°C) after suitable heat treatment.

Corrosion Resistance

Alloy X-750 has excellent resistance to chloride ion stress-corrosion cracking. It exhibits satisfactory resistance to numerous oxidizing environments. The alloy has similar corrosion resistance to alloy 600 in many media.

Physical Properties

Density

lb/cu in……………………………….. 0.300

kg/cu m……………………………….. 8303

Melting Range

°F…………………………………. 2540/2600

°C…………………………………..1393/1427

Thermal Conductivity

Temperature Btu-in/ft²-hr-°F W/m-K
°F °C
300
600
1000
1200
1400
1600
149
316
538
649
760
871
117
142
184
199
218
245
16.9
20.5
26.5
28.7
31.4
35.3

Electrical Resistivity

Condition ohm-cir mil/ft microhm-mm
At Room Temperature
Hot Rolled
Solution Treated
Solution Treated
and Aged
764
716746
1270
11901240

Modulus of Elasticity

Temperature psi x 10(6) MPa x 10(6)
°F °C
80
500
1000
1350
1500
26.7
260.0
538.0
732.0
816.0
31.0
28.7
25.0
21.0
18.5
213.7
197.9
172.4
144.8
127.6

Coefficient of Thermal Expansion

Temperature Range 10(-6)/°F 10(-6)/°C
80°F to 26.7°C to
200
600
1000
1200
1600
93
316
538
649
871
6.7
7.5
7.9
8.1
9.0
12.1
13.5
14.2
14.6
16.2

 

Specific Heat Btu/lb-°F kJ/kg-K
77/212°F (25/100°C)
77/1650°F (25/899°C)
0.10-0.11
0.13
0.42-0.46
0.54

Heat Treatment

Alloy X-750 is austenitic under all conditions. The alloy is heat treated by several different methods depending upon the application or requirement. Two common treatments are:
1. For maximum creep, relaxtion and rupture strength at temperatures above 1100°F (593°C):
Solution Treatment – 2100°F (1149°C), 2 to 4 hrs, air cool.
Intermediate Age – 1550°F (843°C), 24 hrs, air cool.
Final Age –1300°F (704°C), 20 hrs, air cool.
2. For highest room temperature yield strength and tensile ductility:
Stress Equaliztation – 1625°F (885°C), 24 hrs, air cool.
Precipitation Age – 1300°F (704°C), 20 hrs, air cool.

Workability

The furnace temperature should be 2100°F (1149°C)-for optimal starting temperatures of 1950/2000°F. For service below 1100°F (593°C), higher strength can be obtained by combining some cold work with heat treatment because the effects are additive.

Machinabiliy
Alloy X-750 work hardens quickly and is more difficult to machine than most standard ferritic and martensitic alloys. The alloy is most easily machined in the stress-equalized condition. Because specific cutting forces are high, the machine tools used must have ample power and the cutting speed should be slow. The tools must have smooth finishes, be sharp, and be very rigid. To avoid work hardening , a continuous, smooth cutting action should be maintained; thus, the machines must have a minimum of backlash and the tool and workpiece must be rigidly supported. If at all possible, avoid very small cuts and feeds.

Welding
Alloy X-750 should be welded in the stress-equalized condition, 1625°F (885°C) heat treatment, and solution treated and age hardened after welding has been completed. If this is not practical, the alloy should be welded in the solution-treated condition and age hardened after welding with or without the inclusion of a short-period stress-relieving treatment at 1625°F. Weld joints, because of softening of the alloy within the heat-affected zone, should be located where lower creep properties are required.

Typical Mechanical Properties

Room Temperature Mechanical Properties

Temper Tensile Strength,
psi
Yield Strength
0.2% offset, psi
Elongation
in 2″, %
Hardness,
Brinell
Hot-finished + 1300°F/20 hr,A.C

Hot-finished + Annealed
1800°F/1 hr, A.C + 1350°F/
8 hr, F.C. 100°F/hr to
1150°F (total 18 hr), A.C.

Hot-finished + 1625°F/24 hr,
A.C + 1300°F/20 hr, A.C.

Cold-rolled, annealed +
1300°F/20 hr, A.C.

170,000-206,000

162,000-193,000

160,000-188,000

160,000-197,000

120,000-163,000

115,000-142,000

100,000-135,000

105,000-150,000

25-15

30-15

30-15

30-20

313-400

300-390

302-363

300-400

Bar Stock:
Treatment #1

Solution treatment 2100°F (1149°C), 2 to 4 hrs., air cool intermediate age 1550°F (843°C), 24 hrs., air cool
Final age 1300°F (704°C), 20 hrs., air cool

Test
Temperature
Short-Time Tensile Properties Tests
°F °C Yield Strength
0.2% offset
Ultimate
Tensile Strength
% Elongation
in 2″ (50.8 mm)
% Reduction
of Area
ksi MPa ksi MPa
70
1000
1200
1400
1500
21.1
538.0
649.0
760.0
816.0
92
83
82
68
45
634
572
565
469
310
161
140
120
80
47
1110
965
827
552
324
22
20
10
10
20
30
30
21
22
32