Niobium CB-752

FORMS WE CAN PROVIDE

Cb752 Sheet/Plate

Niobium CB-752

Nb752 is a medium-strength niobium alloy. It uses niobium as the base metal, adding no more than 10% tungsten, zirconium and other metal elements and a small amount of carbon to form a solid solution strengthening and a small amount of ZrO2 and (Nb, Zr) C precipitation strengthening a combination of niobium alloy.
At room temperature, the strength of Nb752 is 450-600MPa, the elongation δ=20%-30%, and it still has a fairly high strength between 1000-1400°C. Because Nb752 is more sensitive to interstitial elements such as hydrogen, oxygen, nitrogen, etc., its DBTT is relatively high, and the DBTT in the welding state is generally above room temperature. Therefore, during production and use, the pollution of hydrogen, oxygen, and nitrogen must be strictly controlled, and the oxygen and nitrogen content must be controlled below 80×10^(-6).

Thermal conductivity of CB752
Temperature, ℃ Thermal conductivity, K/cm.s.℃
260 0.091
538 0.107
816 0.116
1093 0.119
1204 0.12
1316 0.121

Main chemical composition of Cb752 (mass fraction)

Grade Chemical Composition / % Chemical Composition / 10-6
Nb W Mo Ta V Hf Zr Ti C O N
Cb752
Nb-10W-2.5Zr		 Balance 9~11 　 　 　 　 2~3 　 10 ＜200 ＜200

Physical properties of Cb752

Grade Component Density /g.cm-3 Melting point /℃ Linear expansion coefficient /℃ Recrystallization temperature /℃ Annealing temperature /℃ Elongation brittle transition temperature /℃
Cb752 Nb-10W-2.5Zr-0.05Mo-0.15Ta-0.1Hf 8.83 4.5（1203℃） 1023~1371 982~1093 -196

Mechanical properties（21℃）of CB752 (Nb-10W-2.5Zr)

Grade Component Elastic Modulus /MPa tensile strength /Mpa Yield Strength /Mpa Elongation (gauge length 50.8mm)%
Cb752 Nb-10W-2.5Zr-0.05Mo-0.15Ta-0.1Hf 112 490 562.5 471.1 27

Forms of Cb752 We Can Provide

Material properties of CB752 (Nb-10W-2.5Zr)

Linear expansion coefficient of CB752
Temperature range, ℃ Average coefficient of thermal expansion,  10-6/℃
20～93 6.85
20～538 7.2
20～871 7.56
20～1093 7.93
20～1204 8.11
Linear expansion coefficient of CB752 at different temperatures

High temperature radiation coefficient of CB752
Test temperature, ℃ eλ
1039 0.32
1214 0.35
1357 0.36
1612 0.35
1740 0.36
1795 0.37
1963 0.33
P.S.: 5mm diameter bar (as machined), single color λ=0.65μM
High temperature performance of CB752
Grade Component Forms Temperature/℃  Tensile Strength/MPa  Temperature/℃ Breaking Strength/MPa
Cb-752 10W、12.5Zr Sheet 1316 182.8 1093 112.5
Notched tensile properties of CB752
Plate thickness, mm Tensile strength, kg/mm2 0.2% Yield Strength, kg/mm2
0.34 52 47.8
52.6 49.4
53.4 48.7
55 52
54.3 48.5
0.46 62 54
60.4 53.3
60.7 52.1
61 53.8
62.7 55.8
Room temperature tensile properties after CB752 coating
Coating system Zr-V-Si(melting)  Ti-Cr-Si(inclusion)①
Basic material Add coating  Add coating  Add coating+1300℃ Add coating+1200℃
Tensile strength, kg/mm2
0.2% yield strength, kg/mm2
Elongation, %		 55.5 44.5 45 48 48
43.5 34 – – –
28.5 13.5 – ＞30.0 ＞16.0
Note 0.8mm sheet, annealed at 1300℃ for 1 hour  1mm sheet, annealed at 1300℃ for 1 hour
① Short sample, K=5.65
High temperature tensile properties after CB752 coating
Test temperature, ℃ 800 1200 1400 1600
Basic Material After coating Basic Material After coating Basic Material After coating Basic Material After coating
Tensile strength, kg/mm2
0.2% yield strength, kg/mm2
Elongation, %		 45.5 30 24 22.5 14.5 12 8 7.5
29 – 19.5 19.5 12.5 10.5 7.5 6.5
15 – 63.5 33 91 42.5 78.5 91
Note：Plate thickness 0.8 mm, cold rolled + 1200 ℃ annealing for 1 hour, Zr-V-Si sintered coating, stretching direction is transverse　　　　　　　　
Durable tensile properties at 1200℃ after CB752 coating
Coating system Basic material① Zr-V-Si Ti-Cr-Si
1 2 3 1 2 3 1 2 3 4 5
Specimen stress, kg/mm2
duration, hours		 10 10 7 8 7.5 6.8 10 8 7.5 7 7
28 ＞28 52.3 14.3 23 23 16 6.8 79 110 ＞111.4
Notes 0.8mm sheet, annealed at 1200℃ for 1 hour 1.0mm sheet, annealed at 1200℃ for 1 hour
①The vacuum degree is 1.0×10-4mm Hg, the test atmosphere is the atmosphere, and the stretching direction is transverse.
Welding performance of CB752
Welding method Basic material Electron beam welding Pulse argon arc welding
Test temperature, ℃ Room temperature Room temperature 1200 1400 1600 Room temperature
Tensile strength, kg/mm2
0.2% yield strength, kg/mm2
Elongation, %		 57 57 20.5 9.5 8 50
– 45 – 　 – –
30 19 8 ＜6.5 24.5 9～16
Creep properties of CB752 (total creep, %)
Alloys Test temperature，℃
1093 1204 1316
CB752 (Nb-10W-2.5Zr) 0.53 3.57 12

Antioxidant properties of CB752 (Nb-10W-2.5Zr)

Niobium, like other refractory metals, has poor oxidation resistance. At present, there are three methods to improve the oxidation resistance of niobium alloys:

1. Add elements with higher atomic valence than niobium, such as molybdenum, tungsten, iridium and vanadium, etc., to overcome the lack of cations in the oxide scale, so as to reduce the diffusion of oxygen through the oxide scale to the oxide and metal interface.

2. Add elements with small ionic radius, such as vanadium, molybdenum, tungsten and aluminum, etc., to reduce the volume ratio of oxide to metal and prevent oxide peeling.

3. Add a large amount of solute elements, such as molybdenum, tungsten, tantalum, titanium and hafnium, etc., to improve the mechanical properties and chemical stability of the oxide scale.

Application of Cb752

Nb752 is suitable for manufacturing riveted and fastened components, such as skins, bolts, nuts, etc.
High temperature and high strength, used in the aerospace industry.