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E: enquiry@qilumetal.com
E: enquiry@qilumetal.com
No. 18 Xiangfu Middle Road,Yuhua District, Changsha City
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C40 / 1.0511 is a widely used carbon quality steel compliant with the European standard EN 10083-2 and EN 10250-2. With a carbon content of 0.37–0.44%, this medium-carbon steel provides a good balance of strength, toughness, and wear resistance after normalizing or quenching and tempering heat treatment.
Its consistent microstructure and reliable mechanical properties make it a suitable choice for components subjected to moderate stresses. Commonly employed in machinery manufacturing, automotive industries, and general engineering, C40 offers good machinability and heat treatability, ensuring reliability and durability in various industrial applications.
1: Steel equivalent
Country | China | Japan | Europe | USA | British |
Standard | GB/T 699 | JIS G4051 | EN10250-2 | ASTM A29 | BS 970 |
Grade | 40 | S40C | C40/1.0511 | 1040 | 080M40 |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr |
| 40 | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | 0.035Max | 0.035Max | 0.25 |
| S40C | 0.37-0.43 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.035Max | 0.20 |
| C40/1.0511 | 0.37-0.44 | 0.40Max | 0.50-0.80 | 0.045Max | 0.045Max | 0.40 |
| 1040 | 0.37-0.44 | 0.10Max | 0.60-0.90 | 0.040Max | 0.050Max | / |
| 080M40 | 0.36-0.44 | 0.10-0.40 | 0.60-1.00 | 0.050Max | 0.050Max | / |
3: Mechanical properties .
Mechanical properties for C40 quenching and tempering carbon steel according to EN10083-2.
Size range | Tensile strength | Yield strength | Alongation | Area of reduction | Impact value At RT/J |
d≤16 t≤8 | 650-800Mpa | 460Mpa Min | 16% Min | 35% Min | / |
16＜d≤40 8＜t≤20 | 630-780Mpa | 400Mpa Min | 18% Min | 40%Min | / |
| 40＜d≤100 20＜t≤60 | 600-750Mpa | 350Mpa Min | 19% Min | 45%Min | / |
Mechanical properties for C40 normalizing carbon steel according to EN10083-2 and ISO683-1.
Size range | Tensile strength | Yield strength | Alongation | Area of reduction | Impact value At RT/J |
d≤16 t≤16 | 580Mpa | 320Mpa Min | 16% Min | / | / |
16＜d≤100 16＜t≤100 | 550Mpa | 290Mpa Min | 17% Min | / | / |
100＜d≤250 100＜t≤250 | 530Mpa | 260Mpa Min | 17% Min | / | / |
Sampling and preparation of test pieces for C40 quenching and tempering steel.
1): According to EN10083-1, all samples shall be taken at a distance of 12.5mm below the heat treated surface
2): As stipulated in the contract between buyer and seller.
Mechanical properties for C40 open die forgings steel in the normalized and normalized and tempered conditions according to EN10250-2.
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
| d≤100 | 550Mpa Min | 290Mpa Min | 17% Min | / | / | / |
| 100＜d≤250 | 530Mpa Min | 260Mpa Min | 17% Min | / | / | / |
Remark: L= Longitudinal Tr = Transverse
Sampling and preparation of test pieces for steel forging.
1: According to EN10250-1, all samples shall be taken at a distance of 4/T below the heat treated surface (with a minimum of 20mm and a maximum of 80mm), and t/2 from the end (where t is the equivalent thickness of the thickness of the ruling section of the forging at the time of heat treatment.
2: As stipulated in the contract between buyer and seller.
4: Surface hardness and hardenability.
Heat Treatment | Hardness |
Treated to improve shearability (+S) | HB160Max |
Soft annealed (+A) | HB145Max |
Quenched and tempred (+QT) | HRC28-32(Common Range) |
Where the steel is ordered by using the symbols for normal (+H) or restricted (+HL, +HH) hardenability requirements, the hardenability values should apply below:
Distance in mm from quenched end | |||||||||||||||||
Distance | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 13 | 15 | 20 | 25 | 30 | |
Hardness In HRC + H | max | 60 | 60 | 59 | 57 | 53 | 47 | 39 | 34 | 31 | 30 | 29 | 28 | 27 | / | / | / |
min | 51 | 46 | 35 | 27 | 25 | 24 | 23 | 22 | 21 | 20 | / | / | / | / | / | / | |
Hardness In HRC + HH | +HH4 | / | / | / | 38-57 | / | / | / | / | / | / | / | / | / | / | / | / |
+HH14 | 54-60 | / | / | 38-57 | / | / | / | / | / | / | / | / | / | / | / | / | |
Hardness In HRC + HL | +HL4 | / | / | / | 27-46 | / | / | / | / | / | / | / | / | / | / | / | / |
+HL14 | 51-57 | / | / | 27-46 | / | / | / | / | / | / | / | / | / | / | / | / | |
Scatter bands for the Rockwell - C hardness in the end quench hardenability test.
5: Supply size & Tolerance & Stock size
Product type | Size range | Length |
Cold drawn bar | Φ3-Φ80mm | 6000-9000mm |
Hot rolled bar | Φ16-Φ310mm | 6000-9000mm |
Hot forged bar | Φ100-Φ1200mm | 3000-5800mm |
Hot rolled plate/sheet | T:3-200mm; W:1500-2500mm | 2000-5800mm |
Hot Forged block | T: 80-800mm; W: 100-2500mm | 2000-5800mm |
Surface Finish | Turned | Milled | Grinding(Best) | Polished(Best) | Peeled(Best) | Black Forged | Black Rolled |
Tolerance | +0/+3mm | +0/+3mm | +0/+0.05mm | +0/+0.05mm | +0/+0.1mm | +0/+5mm | +0/+1mm |
Straighness | 1mm/1000mm max. | 3mm/1000mm max. | |||||
Qilu steel stock hot rolled bar and forged bars more than ten thousands tons every month, below our our stock size.
1): Stock diameter for hot rolled bar
16 | 18 | 20 | 22 | 24 | 25 | 26 | 27 | 28 | 30 | 31 | 32 | 33 | 35 | 36 |
38 | 39 | 40 | 42 | 45 | 46 | 48 | 50 | 52 | 55 | 56 | 58 | 60 | 62 | 63 |
65 | 68 | 70 | 72 | 75 | 78 | 80 | 82 | 83 | 85 | 87 | 90 | 95 | 100 | 105 |
110 | 115 | 120 | 125 | 130 | 135 | 140 | 145 | 150 | 155 | 160 | 170 | 180 | 190 | 200 |
210 | 220 | 230 | 240 | 250 | 260 | 270 | 280 | 290 | 300 | 310 |
2) : Stock diameter for hot forged bar
310 | 320 | 330 | 340 | 350 | 360 | 370 | 380 | 390 | 400 |
410 | 420 | 430 | 440 | 450 | 460 | 470 | 480 | 490 | 500 |
510 | 520 | 530 | 540 | 550 |
Since the stocks change everyday, if you want to know our stock available information, please contact our salesman.
6：Forging processing
Put the C40 ingot into the furnace and heat to 1150-1200℃
Forge the ingot, forging temperature should be not less than 800-850℃
Cooling in the air or in the furnace after forged
7: Heat treatment
Soft annealed:
Heat C40 steel to 840-860℃ in the furnace
Soak at this temperature in the furnace
Cooling in the furnace
Normalized:
Heat C40 steel to 850-910℃ in the furnace
Soak at this temperature in the furnace
Cooling in the air
Quenching and tempering:
Heat C40 steel to 830-870℃ in the furnace
Soak at this temperature in the furnace
Quench in water or oil
Temper steel at 550-660℃ in the furnace
Take out of C40 steel from furnace and cool in the air.
Remark: The conditions given above are for guidance, at the temperatures at the lower end of the range are generally applicable to hardening in water and those at the upper end for hardening in oil.
8: Weldability
C40 steel has very limited weldability due to its medium carbon content of approximately 0.40%. Since weldability significantly decreases with increasing carbon content, steels with carbon levels approaching 0.40% are particularly prone to cracking during welding without extensive preheating and post-weld heat treatment. The high carbon content promotes the formation of hard, brittle martensitic structures in the heat-affected zone (HAZ), increasing susceptibility to cold cracking, especially when hydrogen is present in the welding process.
9：Application
C40 steel, as a classic medium-carbon steel, finds extensive applications. Its performance characteristics include good strength, hardness, and moderate toughness, with its overall mechanical properties further enhanced through heat treatment. Below are the primary application areas and specific uses of C40 steel:
1. Mechanical Manufacturing and Structural Components
Shaft Components: Drive shafts, spindles, mandrels, screws, etc.
Gears and Gear Rings: Used in low-speed, low-load gears for machine tools, automotive transmissions, and similar equipment.
Connectors and Fasteners: High-strength bolts, double-headed studs, pins, etc.
Connecting Rods and Cranks: Employed in mechanical equipment to transmit motion and power.
2. Tools and Molds
Mold Components: Non-core parts of injection molds, mold bases, spacer plates, etc.
Tool bodies: Hand tools like hammers, wrenches, etc.
Blades and cutting tools: Used for manufacturing cutting tools with moderate requirements, woodworking tools, agricultural machinery blades, etc.
3. Automotive Industry
Key components for vehicle manufacturing: Crankshafts, camshafts, steering knuckles, half-shafts, etc.
4. Other Industrial Sectors
Hydraulic and Pneumatic Components: Such as hydraulic cylinder piston rods, pneumatic cylinder rods, etc.
Locomotive Manufacturing: Used to produce locomotive axles, connecting rods, etc.
Agricultural Machinery Equipment: Manufacture parts subjected to wear and impact in agricultural machinery, such as plowshares, gears, etc.
C40 / 1.0511 is a widely used carbon quality steel compliant with the European standard EN 10083-2 and EN 10250-2. With a carbon content of 0.37–0.44%, this medium-carbon steel provides a good balance of strength, toughness, and wear resistance after normalizing or quenching and tempering heat treatment.
Its consistent microstructure and reliable mechanical properties make it a suitable choice for components subjected to moderate stresses. Commonly employed in machinery manufacturing, automotive industries, and general engineering, C40 offers good machinability and heat treatability, ensuring reliability and durability in various industrial applications.
1: Steel equivalent
Country | China | Japan | Europe | USA | British |
Standard | GB/T 699 | JIS G4051 | EN10250-2 | ASTM A29 | BS 970 |
Grade | 40 | S40C | C40/1.0511 | 1040 | 080M40 |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr |
| 40 | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | 0.035Max | 0.035Max | 0.25 |
| S40C | 0.37-0.43 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.035Max | 0.20 |
| C40/1.0511 | 0.37-0.44 | 0.40Max | 0.50-0.80 | 0.045Max | 0.045Max | 0.40 |
| 1040 | 0.37-0.44 | 0.10Max | 0.60-0.90 | 0.040Max | 0.050Max | / |
| 080M40 | 0.36-0.44 | 0.10-0.40 | 0.60-1.00 | 0.050Max | 0.050Max | / |
3: Mechanical properties .
Mechanical properties for C40 quenching and tempering carbon steel according to EN10083-2.
Size range | Tensile strength | Yield strength | Alongation | Area of reduction | Impact value At RT/J |
d≤16 t≤8 | 650-800Mpa | 460Mpa Min | 16% Min | 35% Min | / |
16＜d≤40 8＜t≤20 | 630-780Mpa | 400Mpa Min | 18% Min | 40%Min | / |
| 40＜d≤100 20＜t≤60 | 600-750Mpa | 350Mpa Min | 19% Min | 45%Min | / |
Mechanical properties for C40 normalizing carbon steel according to EN10083-2 and ISO683-1.
Size range | Tensile strength | Yield strength | Alongation | Area of reduction | Impact value At RT/J |
d≤16 t≤16 | 580Mpa | 320Mpa Min | 16% Min | / | / |
16＜d≤100 16＜t≤100 | 550Mpa | 290Mpa Min | 17% Min | / | / |
100＜d≤250 100＜t≤250 | 530Mpa | 260Mpa Min | 17% Min | / | / |
Sampling and preparation of test pieces for C40 quenching and tempering steel.
1): According to EN10083-1, all samples shall be taken at a distance of 12.5mm below the heat treated surface
2): As stipulated in the contract between buyer and seller.
Mechanical properties for C40 open die forgings steel in the normalized and normalized and tempered conditions according to EN10250-2.
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
| d≤100 | 550Mpa Min | 290Mpa Min | 17% Min | / | / | / |
| 100＜d≤250 | 530Mpa Min | 260Mpa Min | 17% Min | / | / | / |
Remark: L= Longitudinal Tr = Transverse
Sampling and preparation of test pieces for steel forging.
1: According to EN10250-1, all samples shall be taken at a distance of 4/T below the heat treated surface (with a minimum of 20mm and a maximum of 80mm), and t/2 from the end (where t is the equivalent thickness of the thickness of the ruling section of the forging at the time of heat treatment.
2: As stipulated in the contract between buyer and seller.
4: Surface hardness and hardenability.
Heat Treatment | Hardness |
Treated to improve shearability (+S) | HB160Max |
Soft annealed (+A) | HB145Max |
Quenched and tempred (+QT) | HRC28-32(Common Range) |
Where the steel is ordered by using the symbols for normal (+H) or restricted (+HL, +HH) hardenability requirements, the hardenability values should apply below:
Distance in mm from quenched end | |||||||||||||||||
Distance | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 13 | 15 | 20 | 25 | 30 | |
Hardness In HRC + H | max | 60 | 60 | 59 | 57 | 53 | 47 | 39 | 34 | 31 | 30 | 29 | 28 | 27 | / | / | / |
min | 51 | 46 | 35 | 27 | 25 | 24 | 23 | 22 | 21 | 20 | / | / | / | / | / | / | |
Hardness In HRC + HH | +HH4 | / | / | / | 38-57 | / | / | / | / | / | / | / | / | / | / | / | / |
+HH14 | 54-60 | / | / | 38-57 | / | / | / | / | / | / | / | / | / | / | / | / | |
Hardness In HRC + HL | +HL4 | / | / | / | 27-46 | / | / | / | / | / | / | / | / | / | / | / | / |
+HL14 | 51-57 | / | / | 27-46 | / | / | / | / | / | / | / | / | / | / | / | / | |
Scatter bands for the Rockwell - C hardness in the end quench hardenability test.
5: Supply size & Tolerance & Stock size
Product type | Size range | Length |
Cold drawn bar | Φ3-Φ80mm | 6000-9000mm |
Hot rolled bar | Φ16-Φ310mm | 6000-9000mm |
Hot forged bar | Φ100-Φ1200mm | 3000-5800mm |
Hot rolled plate/sheet | T:3-200mm; W:1500-2500mm | 2000-5800mm |
Hot Forged block | T: 80-800mm; W: 100-2500mm | 2000-5800mm |
Surface Finish | Turned | Milled | Grinding(Best) | Polished(Best) | Peeled(Best) | Black Forged | Black Rolled |
Tolerance | +0/+3mm | +0/+3mm | +0/+0.05mm | +0/+0.05mm | +0/+0.1mm | +0/+5mm | +0/+1mm |
Straighness | 1mm/1000mm max. | 3mm/1000mm max. | |||||
Qilu steel stock hot rolled bar and forged bars more than ten thousands tons every month, below our our stock size.
1): Stock diameter for hot rolled bar
16 | 18 | 20 | 22 | 24 | 25 | 26 | 27 | 28 | 30 | 31 | 32 | 33 | 35 | 36 |
38 | 39 | 40 | 42 | 45 | 46 | 48 | 50 | 52 | 55 | 56 | 58 | 60 | 62 | 63 |
65 | 68 | 70 | 72 | 75 | 78 | 80 | 82 | 83 | 85 | 87 | 90 | 95 | 100 | 105 |
110 | 115 | 120 | 125 | 130 | 135 | 140 | 145 | 150 | 155 | 160 | 170 | 180 | 190 | 200 |
210 | 220 | 230 | 240 | 250 | 260 | 270 | 280 | 290 | 300 | 310 |
2) : Stock diameter for hot forged bar
310 | 320 | 330 | 340 | 350 | 360 | 370 | 380 | 390 | 400 |
410 | 420 | 430 | 440 | 450 | 460 | 470 | 480 | 490 | 500 |
510 | 520 | 530 | 540 | 550 |
Since the stocks change everyday, if you want to know our stock available information, please contact our salesman.
6：Forging processing
Put the C40 ingot into the furnace and heat to 1150-1200℃
Forge the ingot, forging temperature should be not less than 800-850℃
Cooling in the air or in the furnace after forged
7: Heat treatment
Soft annealed:
Heat C40 steel to 840-860℃ in the furnace
Soak at this temperature in the furnace
Cooling in the furnace
Normalized:
Heat C40 steel to 850-910℃ in the furnace
Soak at this temperature in the furnace
Cooling in the air
Quenching and tempering:
Heat C40 steel to 830-870℃ in the furnace
Soak at this temperature in the furnace
Quench in water or oil
Temper steel at 550-660℃ in the furnace
Take out of C40 steel from furnace and cool in the air.
Remark: The conditions given above are for guidance, at the temperatures at the lower end of the range are generally applicable to hardening in water and those at the upper end for hardening in oil.
8: Weldability
C40 steel has very limited weldability due to its medium carbon content of approximately 0.40%. Since weldability significantly decreases with increasing carbon content, steels with carbon levels approaching 0.40% are particularly prone to cracking during welding without extensive preheating and post-weld heat treatment. The high carbon content promotes the formation of hard, brittle martensitic structures in the heat-affected zone (HAZ), increasing susceptibility to cold cracking, especially when hydrogen is present in the welding process.
9：Application
C40 steel, as a classic medium-carbon steel, finds extensive applications. Its performance characteristics include good strength, hardness, and moderate toughness, with its overall mechanical properties further enhanced through heat treatment. Below are the primary application areas and specific uses of C40 steel:
1. Mechanical Manufacturing and Structural Components
Shaft Components: Drive shafts, spindles, mandrels, screws, etc.
Gears and Gear Rings: Used in low-speed, low-load gears for machine tools, automotive transmissions, and similar equipment.
Connectors and Fasteners: High-strength bolts, double-headed studs, pins, etc.
Connecting Rods and Cranks: Employed in mechanical equipment to transmit motion and power.
2. Tools and Molds
Mold Components: Non-core parts of injection molds, mold bases, spacer plates, etc.
Tool bodies: Hand tools like hammers, wrenches, etc.
Blades and cutting tools: Used for manufacturing cutting tools with moderate requirements, woodworking tools, agricultural machinery blades, etc.
3. Automotive Industry
Key components for vehicle manufacturing: Crankshafts, camshafts, steering knuckles, half-shafts, etc.
4. Other Industrial Sectors
Hydraulic and Pneumatic Components: Such as hydraulic cylinder piston rods, pneumatic cylinder rods, etc.
Locomotive Manufacturing: Used to produce locomotive axles, connecting rods, etc.
Agricultural Machinery Equipment: Manufacture parts subjected to wear and impact in agricultural machinery, such as plowshares, gears, etc.
