DD4

HuaNickel DD4 is a nickel-based precipitation-hardening single-crystal superalloy, which belongs to the first generation of single-crystal superalloy with a service temperature of less than 1050°C. The alloy has good medium and high temperature properties, and has good oxidation and corrosion resistance. The alloy has a light specific gravity, low cost, and good process performance. The main products are turbine rotors and guide vanes.

DD4Chemical composition：

	Ti	Cr	Co	W	Mo	AI	Ti	Nb	Ta	Fe	B	Zr	Mn	Si	S	P	As
Min	Bal	8.5	7	5.5	1.4	3.4	3.9	0.35	3.5	≤
Max		9.5	8	6.5	2	4	4.7	0.7	4.8	0.5	0.01	0.05	0.2	0.2	0.01	0.01	0.001

DD4Physical properties：

Density	8.49g/cm³
Melting point	1284℃~1339℃
Magnetic properties	not

Specific heat capacity

θ/℃	200	300	400	500	600
c/[J/(kg·℃)]	389	414	443	468	489
θ/℃	700	800	900	1000	—
c/[J/(kg·℃)]	514	535	552	563

Coefficient of linear expansion

θ/℃	20～100	20～200	20～300	20～400	20～500
α/(10-6℃-1)	12.02	12.87	13.37	13.37	14.04
θ/℃	20～600	20～700	20～800	20～900	20～1000
α(10-5℃-¹)	14.34	14.80	15.21	15.67	16.58

DD4Mechanical properties：

Standard number	Variety	Heat treatment	Long-lasting performance			760℃Tensile properties
			θ/℃	σ/MPa	τ/h	σb/MPa	δ₅/%	ψ/%
Q/6SZ 1311	[001]Monocrystalline test sticks	standard Heat treatment	760	800	≥50	≥850	≥8	≥8
			1040	145	≥70

DD4Alloy properties：

HuaNickel DD4 alloy can be surface treated using solid or vapor phase permeability Al as well as vapor phase physical deposition. After 1000h exposure at 850°C and 950°C, the microstructure remained unchanged except for the slight growth of the γ’ phase, and no TCP phase precipitation was found.

DD4Uses of alloys：

HuaNickel DD4 alloy has been used to make high-temperature components for advanced aero engines. The alloy is suitable for making turbine rotors with an actual service temperature of about 1000°C, guide vanes and other high-temperature parts at about 1050°C.

DD4Process performance：

Heat treatment: Parts should be carried out under vacuum or argon protective atmosphere, Heat treatment specification is: 1260 °C± 10 °C× 2h/WQ+1080 °C± 10 °C× 4h/AC+900 °C± 10 °C×16h/AC.

Relevant standards：

GB/T14992 、Q/6SZ 1311