DD8

HuaNickel DD8 is a nickel-based precipitation-hardening single-crystal superalloy with a service temperature of less than 1000°C. The alloy has high creep strength and fatigue resistance, good single crystal casting properties, and has good microstructure stability. The alloy can work in the oxidizing atmosphere and hot corrosion environment for a long time, and its oxidation resistance and hot corrosion resistance are better than those of K438 alloy; The temperature bearing capacity is about 40°C higher than that of K438 alloy and about 20°C higher than that of DZ438G alloy. It is suitable for the manufacture of turbine blades of coastal aircraft engines and turbine blades of naval gas turbines and other high-temperature components for working below 1000°C.

DD8Chemical composition：

	Ni	Cr	Co	W	AI+Ti	AI	Ti	Ta	Fe	B	Zr	Mn	Si	P	S	Cu
Min	Bal	15.5	8	5.6	7.5	3.6	3.6	0.7	≤
Max		16.5	9	6.4	7.9	4.2	4.2	1.2	0.5	0.005	0.007	0.15	0.15	0.01	0.01	0.1

DD8Physical properties：

Density	8.26g/cm³
Melting point	1295℃~1360℃
Magnetic properties	not

Coefficient of linear expansion

θ/℃	20～100	20～200	20～300	20～400	20～500
α/(10~6℃-1)	10.90	11.20	11.60	12.10	12.50
θ/℃	20～600	20～700	20～800	20～900	20～950
α/(10-6℃-1)	12.90	13.20	13.50	13.80	14.00

Resilient performance

θ/℃	18	100	200	300	410	500
Ed/GPa	215	210	210	205	200	190
θ/℃	600	700	800	900	950
Ed/GPa	185	180	170	165	155

DD408Mechanical properties：

Standard number	Variety	sampling	Heat treatment	Long-lasting performance
				θ/℃	σ/MPa	t/h
GJB 5512.3、Q/KJ.J02.13	Master alloy	[001]Monocrystalline test sticks	Standard heat treatment	850	480	≥100

DD408Alloy properties

HuaNickel DD8 alloy has less precious metal element content, lower density, and lower price. The surface of the part is coated with solid powder permeated Al or vapor permeable Al to prepare a surface protective coating, which can further improve the hot corrosion resistance of the alloy. The alloy does not precipitate the TCP phase after long-term aging.

DD408Uses of alloys：

DD8alloy has been used to make high-pressure turbine working blades for an advanced aero engine, and has passed component tests.

DD408Process performance：

Parts Hittritment: Parts must not be struck, hammered and collided with each other before Hitterritement, during Hittriitmentment, and after Hittritmentment. Machining and sandblasting are not allowed in the pre-Hitterrite Gate and Hitterlit Gate processes.

Relevant standards：

GB/T  14992 、GJB 5512.3、Q/KJ.J02.13