Electric heating radiation tube is a type of heating element that is enclosed in a protective sleeve and heated by electricity. The sleeve indirectly radiates the heat to the furnace lining and the processed workpiece, and is widely used in various heating furnaces in the heat treatment industry. The electric radiation tube is mainly composed of a heat-resistant steel alloy sleeve and a heater, which is wound around a heat-resistant insulating ceramic tube core with a spiral groove by an electric heating wire.
The advantages of this radiation tube are:
① Can be replaced at work without affecting production;
② More reasonable power distribution;
③ Beneficial for the flow of atmosphere inside the furnace;
④ With process changes, it is convenient to increase or decrease furnace power, adjust heating capacity, and other advantages.
Our radiant tubes are designed for use not only in domestic heat treatment equipment but also as replacement components for imported heat treatment systems. In 1998, this product line was awarded the Gold Medal at the National Technology Exhibition.
The heating element (tube core) inside the radiant tube is available in several configurations: cage type, vertical strip-wound type, and spiral-wound resistance wire type. The resistance wire materials used are nickel-chromium (Ni-Cr) and iron-chromium (Fe-Cr) alloys. The surface load is typically designed at ≤1 W/cm², with single-tube power ratings ranging from 3kW to 60kW. The operating temperature of the heating element ranges from 500°C to 1300°C.
The outer protective tube is manufactured in three types: centrifugally cast tubes, rolled and welded tubes, and seamless tubes.
In terms of service life:
Quenching furnaces: ≥1 year
Tempering furnaces: ≥3 years
Gas-fired radiant tubes: ≥2 years
For sleeve tube materials, please refer to the table below.
| Grade/Performance | 1Cr13Al4 | 0Cr25Als | OCr21Al₆ | 0Cr2₁Al₆Nb | 0Cr27Al₇NO₂ | Cr15Ni₆o | Cr2₀Ni₆o | Cr20Ni30 | |
| Main chemical components% | Cr | 12-15 | 23-26 | 19-22 | 21.0-23.0 | 26.5-27.8 | 15-18 | 20-23 | 20 |
| AL | 4-6 | 4.5-6.5 | 5-7 | 5-7 | 6-7 | ||||
| Fe | Balance | Balance | Balance | Balance | Balance | Balance | Balance | ||
| Re | Appropriate Amount | Appropriate Amount | Appropriate Amount | Appropriate Amount | Appropriate Amount | Appropriate Amount | Appropriate Amount | Appropriate Amount | |
| Mo | 1.8-2.2 | ||||||||
| Nb | 0.5 | 0.5 | |||||||
| Ni | 58-62 | Balance | 28-32 | ||||||
| Maximum operating temperature of components℃ | 950 | 1250 | 1250 | 1350 | 1400 | 1100 | 1150 | 1100 | |
| Density/cm³ | 7.4 | 7.1 | 7.1 | 7.1 | 7.1 | 8.2 | 8.4 | 7.9 | |
| ResistivityΩmm²/m | 1.25±0.05 | 1.42±0.05 | 1.42±0.05 | 1.42±0.05 | 1.53±0.05 | 1.13±0.05 | 1.14±0.05 | 1.04±0.05 | |
| Temperature coefficient of resistance×10-51℃ | 15 | 5 | 5 | 5 | -1 | 14 | 8.5 | ||
| Melting Point℃ | 1450 | 1500 | 1500 | 1500 | 1520 | 1390 | 1400 | 1390 | |
| Tensile StrengthMPa | 588-735 | 637-784 | 637-784 | 637-784 | 686-784 | 637-784 | 637-784 | 637-784 | |
| Elongation% | >14 | >12 | >12 | >12 | >12 | >20 | >20 | >20 | |
| Reduction of area% | 65-75 | 65-75 | 65-75 | 65-75 | 65-75 | 60-75 | 60-70 | 65-75 | |
| Number of bends | >5 | >5 | >5 | >5 | >5 | ||||
| Hardness | 200-260 | 200-260 | 200-260 | 200-260 | 200-260 | 130-150 | 130-150 | 130-150 | |
| Organization | Ferrites(F) | Ferrites(F) | Ferrites(F) | Ferrites(F) | Ferrites(F) | Austenitic (A) | Austenitic (A) | Austenitic (A) | |
| Magnetism | Magnetism | Magnetism | Magnetism | Magnetism | Magnetism | Non-magnetic | Non-magnetic | Non-magnetic | |

Radiation tube production site

Radiation tube, flaw detection

Finished Product

W-shaped radiation tube

U-shaped radiation tube

Elbow

On site casting of pipes

Radiation tube pressure test
| AS5 HK40 | KHR 12C | KHR 35H | KHR S2 | KHR S3 | KHR 48N | KHR SA | ||||||||||||||||
| Chemical Composition (weight%) |
C | 0.35/0.45 | 0.3/0.4 | 0.37/0.47 | 0.35/0.45 | 0.45/0.55 | 0.44/0.6 | 0.4/0.5 | ||||||||||||||
| Si | 1.75max. | 1.0max | 1.5max | 2.0max | 2.0max | 1.5max | 0.5max | |||||||||||||||
| Mn | 1.5 max. | 1.1max | 1.5max | 2.0max | 2.0max | 1.5max | 0.3/0.6 | |||||||||||||||
| Ni | 19/22 | 13/15 | 34/37 | 22/25 | 33/37 | 45/50 | 47/51 | |||||||||||||||
| Cr | 23/27 | 23/26 | 24/28 | 24/27 | 24/28 | 25/30 | 28/31 | |||||||||||||||
| Co | 一 | 一 | 一 | 14/18 | 14/16 | 一 | 一 | |||||||||||||||
| Nb | 一 | 0.8/1.5 | 一 | - | 一 | 二 | 一 | |||||||||||||||
| W | - | 一 | - | 1.8/2.3 | 4.0/6.0 | 4.0/6.0 | 12/14 | |||||||||||||||
| Mo | 0.5max. | 一 | 1.0/1.5 | 一 | 二 | 一 | 一 | |||||||||||||||
| Other elements | 一 | 一 | 二 | - | 一 | 一 | 一 | |||||||||||||||
| Tensile performance at room temperature | Tensile Strength(kgf/mm²) | 425min. (43.3min.) |
440min. (45min.) |
440min. (45min.) |
490min. (50min.) |
490min. (50min.) |
390min. (40min.) |
490min. (50min.) |
||||||||||||||
| Stubborn clothing strength(kgf/mm²) | 240min. (24.5min.) |
245min. (25min.) |
245min. (25min.) |
245min. (25min.) |
245min. (25min.) |
295min. (30min.) |
295min. (30min.) |
|||||||||||||||
| Elongation (%) |
Centrifugal Casting | 10min | 10min | 8min | 8min | 8min | 5min | 一 | ||||||||||||||
| Static Casting | 10min | 10min | 6min | 6min | 6min | 5min | 一 | |||||||||||||||
| KHR 24C | KHR 20T | KHR 32C | KHR 35C | KHR 35CT | ||||||||||||||||||
| Chemical Composition ( weight % ) |
C | 0.25/0.35 | 0.35/0.5 | 0.11/0.16 | 0.4/0.5 | 0.45/0.55 | ||||||||||||||||
| Si | 1.0 max. | 1.5 max. | 1.2max. | 1.5max. | 1.5 max. | |||||||||||||||||
| Mn | 1.5max. | 2.0 max. | 1.5max. | 1.5max. | 2.0 max. | |||||||||||||||||
| Ni | 23/26 | 19/25 | 33.5/35.5 | 34/37 | 33/37 | |||||||||||||||||
| Cr | 23/26 | 23/27 | 19/20.5 | 24/28 | 24/27 | |||||||||||||||||
| Nb | 1.0/2.0 | 0.5max | 0.6/1.6 | 0.6/1.5 | 1.0 max. | |||||||||||||||||
| Mo | 0.5max. | 一 | 一 | 一 | - | |||||||||||||||||
| Other elements | Addition | 一 | 一 | Addition | ||||||||||||||||||
| Tensile performance at room temperature | Tensile Strength(kgf/mm²) | 440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
||||||||||||||||
| Stubborn clothing strength(kgf/mm²) | 245min. (25min.) |
245min. | 175min. (18min.) |
235min. | 25min.) | |||||||||||||||||
Elongation (%) |
Centrifugal Casting | 15min | 10min | 30min | 8min | 8min | ||||||||||||||||
| Static casting | 12min | 8min | 25min | 6min | 6min | |||||||||||||||||
| KHR35H-HiSi | KHR 35CL | KHR 30A | KHR35C-HiSi | KHR 35CW | KHR35CT-HiSi | KHR 35W | KHR 45A | ||||||||||||||
| Chemical Composition ( Weight % ) |
C | 0.37/0.47 | 0.18/0.23 | 0.55/0.65 | 0.4/0.5 | 0.4/0.5 | 0.45/0.55 | 0.4/0.5 | 0.4/0.6 | ||||||||||||
| Si | 1.5/2.0 | 0.5/1.2 | 2.5 max. | 1.5/2.0 | 1.5/2.0 | 1.5/2.0 | 2.0 max. | 2.0 max. | |||||||||||||
| Mn | 1.5max. | 1.5max. | 1.5 max. | 1.5max. | 1.5 max. | 2.0 max. | 2.0 max. | 2.0 max. | |||||||||||||
| Ni | 34/37 | 36.5/38.5 | 29.5/32.5 | 34/37 | 34/37 | 33/37 | 34/37 | 40/46 | |||||||||||||
| Cr | 24/28 | 24/26 | 22/25 | 24/28 | 24/28 | 24/27 | 24/28 | 30/35 | |||||||||||||
| Nb | 一 | 1.5max. | - | 0.6/1.5 | 1.1/1.7 | 1.0 max. | - | 0.5/1.8 | |||||||||||||
| W | - | - | - | - | 0.5/1.5 | - | 3/4.5 | - | |||||||||||||
| Mo | 1.0/1.5 | 一 | 一 | - | 0.3/0.8 | 一 | - | - | |||||||||||||
| Other elements | 一 | - | Addition | - | Nd+W+Mo 3.0max. |
Additon | 一 | Addition | |||||||||||||
| Tensile performance at room temperature | Tensile Strength(kgf/mm²) | 440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
440min. (45min.) |
||||||||||||
| Stubborn clothing strength(kgf/mm²) | 235min. (24min.) |
185min. (19min.) |
225min; (23min.) |
225min. (23min.) |
235min (24min.) |
225min (23min.) |
235min. (24min.) |
235min. (24min.) |
|||||||||||||
| Elongation (%) |
Centrifugal casting | 8min | 25min | 5min | 8min | 8min | 8min | 5min | 5min | ||||||||||||
| Static casting | 6min | 20min | 6min | 6min | 6min | 3min | 3min | ||||||||||||||
| Mechanical properties at room temperature | |||||||
| Serial Number | Steel Grade | Yield Strengthαs ≥Mpa |
Tensile Strengthαb ≥Mpa |
Elongationδ ≥% |
|||
| 1 | ZG30Cr28Ni4 | 345 | |||||
| 2 | ZG50Cr28Ni6 | 560 | |||||
| 3 | ZG35Cr24Ni7SiN | 340 | 540 | 12 | |||
| 4 | ZG35Cr28Ni10 | 275 | 490 | 8 | |||
| 5 | ZG30Cr26Ni12 | 235 | 490 | 8 | |||
| 6 | ZG33Cr25Ni14 | 235 | 490 | 8 | |||
| 7 | ZG35Cr28Ni16 | 235 | 490 | 8 | |||
| 8 | ZG30Cr25Ni20 | 245 | 440 | 10 | |||
| 9 | ZG40Cr25Ni20 | 235 | 440 | 10 | |||
| 10 | ZG40Cr25Ni20Si2 | 245 | 431 | 10 | |||
| 11 | ZG45Cr24Ni24NbTi | 245 | 441 | 8 | |||
| 12 | ZG30Cr30Ni20 | 245 | 450 | 8 | |||
| 13 | ZG40Cr30Ni20 | 245 | 450 | 8 | |||
| 14 | ZG40Ni25Cr21 | 390 | 5 | ||||
| 15 | ZG14Ni32Cr20Nb | 186 | 448 | 25 | |||
| 16 | ZG40Ni35Cr25 | 235 | 440 | 5 | |||
| 17 | ZG40Ni35Cr25Nb | 245 | 441 | 8 | |||
| MECHANICAL PROPERTIES AT ROOM TEMPERATURE | |||||||||
| Serial Number | Steel Grade | Yield Strengthαs | Tensile Strengthαb | Elongationδ ≥% |
|||||
| 18 | ZG40Ni35Cr25NbW | 221 | 448 | 8 | |||||
| 19 | ZG50Ni35Cr17 | 440 | 4 | ||||||
| 20 | ZG50Ni39Cr19 | 440 | 4 | ||||||
| 21 | ZG45Ni48Cr28W5Si2 | 242 | 392 | 3 | |||||
| 22 | ZG40Ni48Cr30W15Si2 | 295 | 490 | 2 | |||||
| 23 | ZG50Ni36Cr26Co15W5 | 315 | 480 | 3 | |||||
| 24 | ZG42Ni33Cr25Nb | 250 | 450 | 8 | |||||
| 25 | ZG45Ni35Cr27NbW | 265 | 448 | 12 | |||||
| 26 | ZG50Ni48Cr18W5 | 245 | 448 | 3.5 | |||||
| 27 | ZG10Ni32Cr20Nb | 186 | 448 | 25 | |||||
| 28 | ZG45Ni48Cr28W5Co5 | 242 | 448 | 5 | |||||
| 29 | ZG35Ni24Cr18Si2 | 195 | 390 | 5 | |||||
| 30 | ZG30Ni35Cr15 | 195 | 440 | 13 | |||||
| 31 | ZG45Ni35Cr25NbM | 250 | 450 | 8 | |||||
| 32 | ZG40Ni35Cr25W4 | 250 | 450 | 7 | |||||
| 33 | ZG35Cr24Ni7SiN(Re) | 340 | 540 | 12 | |||||
| 34 | ZG10Ni35Cr25Nb | 186 | 448 | 25 | |||||
| S T R E S S - R U P T U R E P R O P E R T I E S | ||||||||||||||||||
| Grade | 700℃ | 800℃ | 900℃ | 1000℃ | 1100℃ | |||||||||||||
| Tensile Strength, αb≥Mpa |
Extension, δ5≥% |
Tensile Strength, αb≥Mpa |
Extension, δ5≥% |
Tensile Strength, αb≥Mpa |
Extension, δ5≥% |
Tensile Strength, αb≥Mpa |
Extension, δ5≥% |
Tensile Strength, αb≥Mpa |
Extension, δ5≥% |
|||||||||
| ZG45Ni35Cr27NbW | 147 | 53 | 97 | 62 | 63 | 65 | ||||||||||||
| ZG14Ni32Cr20Nb | 86.2 | 24.8 | ||||||||||||||||
| ZG10Ni32Cr20Nb | 296 | 39 | 196 | 49 | 102 | 67 | 68 | 75 | ||||||||||
| ZG10Ni35Cr25Nb | 275(750℃) | 36(750℃) | 150(850℃) | 44(850℃) | 83(950℃) | 54(950℃) | 55(1050℃) | 62(1050℃) | ||||||||||
| ZG40Ni35Cr25Nb | 265 | 20 | 147 | 30 | 93 | 38 | 61 | 39 | ||||||||||
| ZG45Ni35Cr25NbM | 256 | 31 | 172 | 38 | 117 | 43 | 82 | 45 | ||||||||||
| ZG40Ni35Cr25W4 | 243 | 26 | 175 | 33 | 118 | 40 | 70 | 47 | ||||||||||
If you would like to learn more about our products, please feel free to contact us. We are dedicated to providing you with the assistance you need.