What is Carbon
Carbon is a very common non-metallic element, which exists widely in the atmosphere, crust and living things in various forms. The Latin word for carbon is Carbonium, which means "coal, charcoal". Elemental carbon has been recognized and utilized for a long time, and a series of carbon compounds - organic matter is the foundation of life. Carbon is one of the constituents of pig iron, wrought iron and steel. Carbon can chemically combine with itself to form a large number of compounds. It is a biologically and commercially important molecule. The vast majority of molecules in living organisms contain carbon.
| I | O | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 H |
II | III | IV | V | VI | VII | 2 He |
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| 2 | 3 Li |
4 Be |
5 B |
6 C |
7 N |
8 O |
9 F |
10 Ne |
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| 3 | 11 Na |
12 Mg |
III | IV | V | VI | VII | VIII | I | II | 13 Al |
14 Si |
15 P |
16 S |
17 Cl |
18 Ar |
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| 4 | 19 K |
20 Ca |
21 Sc |
22 Ti |
23 V |
24 Cr |
25 Mn |
26 Fe |
27 Co |
28 Ni |
29 Cu |
30 Zn |
31 Ga |
32 Gc |
33 As |
34 Se |
35 Br |
36 Kr |
| 5 | 37 Rb |
38 Sr |
39 Y |
40 Zr |
41 Nb |
42 Mo |
43 Tc |
44 Ru |
45 Rh |
46 Pd |
47 Ag |
48 Cd |
49 In |
50 Sn |
51 Sb |
52 Te |
53 I |
54 Xe |
| 6 | 55 Cs |
56 Ba |
57-71 La-Lu |
72 Hf |
73 Ta |
74 W |
75 Re |
76 Os |
77 Ir |
78 Pt |
79 Au |
80 Hg |
81 Tl |
82 Pb |
83 Bi |
84 Po |
85 At |
86 Rn |
| 7 | 87 Fr |
88 Ra |
89-103 Ac-Lr |
104 Rf |
105 Db |
106 Sg |
107 Bh |
108 Hs |
109 Mt |
110 Ds |
111 Rg |
112 Uub |
||||||
| La-Lu | 57 La |
58 Ce |
59 Pr |
60 Nd |
61 Pm |
62 Sm |
63 Eu |
64 Gd |
65 Tb |
66 Dy |
67 Ho |
68 Er |
69 Tm |
70 Yb |
71 Lu |
|||
| Ac-Lr | 89 Ac |
90 Th |
91 Pa |
92 U |
93 Np |
94 Pu |
95 Am |
96 Cm |
97 Bk |
98 Cf |
99 Es |
100 Fm |
101 Md |
102 No |
103 Lr |
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- Item Name: Carbon
- Element Symbol: C
- Atomic Number: 6
- Atomic Weight: 12.011
- Atomic Radius: 77pm
- Density: 1.8g/cm3
- Melting Point: 3500°C
- Boiling Point: 4827°C
- Electronic Layout: [He]2s22p2
The Atomic Structure of Carbon
Refining Effect of Carbon
During smelting, it is often necessary to ensure the vacuum degree of the environment. If oxygen enters the alloy, pores will be formed inside the alloy. During subsequent further processing, these pores have the potential to propagate microcracks. Therefore, a certain amount of carbon is often added during smelting. Carbon can combine with oxygen at high temperatures to form carbon dioxide or carbon monoxide gas. After the carbon has absorbed the oxygen, the purity of the alloy is assured.
Intergranular Strengthening Effect of Carbon
The carbon in the superalloy mainly forms carbides, and the carbides precipitated during the solidification of the liquid metal are primary carbides, which are mainly distributed in the grain boundaries or between the dendrites. Bulk primary carbides often become fatigue crack sources and propagation channels. Carbon in superalloys can improve mechanical properties by forming carbides. Granular discontinuous carbides precipitated at grain boundaries can prevent crystal sliding and crack propagation. It also increases the durability of the alloy and improves ductility and toughness.
The graph below shows the effect of carbon content on the alloy's durable properties. It can be seen that when the carbon content increases from 0.01% to 0.03%, the durable performance increases by 2-3 times. The durable performance reaches the highest value when the carbon content is between 0.03% and 0.05%. If the carbon content is further increased, the durable performance drops drastically. Therefore, in order to obtain higher durable strength, plasticity and good tensile properties, the carbon content should be controlled at about 0.03% to 0.05%.
The Effect of Carbon Content on the Alloy's Durable Properties
Corrosion Resistance Effect of Carbon
Carbon also plays an important role in the hot corrosion resistance of the alloy. For some alloys, the corrosion resistance of the alloy is significantly improved with increasing carbon content. When the carbon content is below 0.1%, the corrosion of the alloy is very serious at around 800 °C. The relationship between the corrosion degree of the alloy and the corrosion time is basically proportional. When the carbon content is more than 0.1%, the corrosion of the alloy is greatly improved, and the relationship between the corrosion degree and time becomes a parabolic curve. When the carbon content exceeds 0.2%, the improvement effect of carbon addition on corrosion is no longer obvious.
Adverse Effect of Carbon
In some niobium-containing alloys (eg Inconel 718), carbon forms predominantly NbC-type inclusions. The volume percentage and density of such inclusions increase with increasing carbon content. The increase of such inclusions can impair the purity of the alloy. The long-term ductility of the alloy decreases significantly with the increase of carbon content, and the notch permanent life decreases significantly.
718
Si
C
Al
Ti
Co
Nb
Ta
Mo
Fe
Cr
Ni
Conclusion
In the smelting of superalloys, carbon can play a refining role. Carbon can also improve the tensile properties and lasting strength of the alloy. In some alloys, carbon acts to improve corrosion resistance. In some niobium-containing alloys, carbides can reduce the notch durability of the alloy.
We produce superalloys in strict accordance with the requirements. Whether it's a low carbon alloy or you need to control the carbon content, we can do it. If you have any needs, please contact us.
