The Inconel X-750 bar or forging refers to the precipitation-hardening nickel alloy bar or forging manufactured to ASTM B637 UNS N07750. It should be either hot worked or cold worked and is primarily used for high-temperature service.

Chemical Composition of Inconel X-750 Bar & Forging

C	Mn	Si	S	Cr	Co	Nb+Ta	Ti	Al	Fe	Cu	Ni
≤0.08	≤1.00	≤0.50	≤0.01	14.00~17.00	≤1.00	0.70~1.20	2.25~2.75	0.40~1.00	5.00~9.00	≤0.50	≥70.00

*All values are in % unit.

Heat Treatment for Inconel X-750 Bar & Forging

Bars or forgings of ASTM B637 Gr.N07750 can be categorized into 3 types according to heat treatment furnished.

• N07750 Type 1: for service above 1100°F [593°C]; first, solution treated at 2100±25°F [1149±14°C], hold 2~4 hours, air cool; then, stabilizing treated at 1550±25°F [843 ± 14°C], hold 24 hours, air cool; finally, precipitation hardening treated at 1300±25°F [704 ± 14°C], hold 20 hours, air or furnace cool.
• N07750 Type 2: for service up to 1100°F [593°C]; first, solution treated at 1800±25°F [982±14°C], hold minimum 0.5 hours, air cool or faster; then, precipitation hardening treated at 1350±25°F [732±14°C], hold 8 hours, furnace cool to 1150±25°F [621±14°C], hold until total precipitation heat treatment has reached 18 hours, air cool.
• N07750 Type 3: first, solution treated at 1975–2050°F [1079–1121°C], hold 1~2 hours, air cool; then precipitation hardening treated at 1300±25°F [704±14°C], hold 20~24 hours, air cool.

Mechanical Properties of Inconel X-750 Bar & Forging

Alloy UNS	Tensile Strength, min.		Yield Strength, min.		Elongation	Reduction of Area	Brinell Hardness
N07750	ksi	MPa	ksi	MPa	min. %	min. %	HB
*Type 1	140	965	90	620	8	-	≥262
*Type 2a	170	1170	115	790	18	18	302~363
*Type 2b	170	1170	115	790	15	15	302~363
*Type 3	160~185	1103~1276	100~130	689~896	20	20	267~363

*Type 1:  solution at 2100°F [1149°C] + stabilize + precipitation hardening.
*Type 2^a: solution at 1800°F [982°C] + precipitation hardening, for diameter < 2.5″ [63.5 mm].
*Type 2^b: solution at 1800°F [982°C] + precipitation hardening, for 2.5″ ≤ diameter < 4″ [63.5 mm ≤ d < 101.6 mm].
*Type 3:  solution anneal at 2000°F [1093°C] + precipitation hardening.

Stress-Rupture Requirements of Inconel X-750 Bar & Forging

When the ASTM B637 Gr. N07750 bar or forging is supplied in the solution treated plus aged condition(precipitation hardening), it shall take the stress-rupture test: for N07750 Type 1 with heat treatment of solution + stabilizing + precipitation hardening, at test temperature of 1350°F [732°C] & under a stress of 45 ksi [310 MPa], the practical time period for rupture shall be no less than 100 hours with minimum 5% elongation.