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C45 / 1.0503 is a carbon structural steel belonging to the European standards EN 10083-2 and EN 10250-2. It is widely used in several industries, such as machine building, automotive industry, construction and general engineering. Therefore, you can find its equivalents in different national standards, such as American Standard ASTM 1045 (ASTM A20), Japanese Standard S45C (JIS G4051), Chinese Standard 45# (GB/T 699) and British Standard EN8D/080M40 (BS 970).
C45 is a medium carbon steel series with a carbon content of 0.42-0.50%. After heat treatment (e.g. normalizing or tempering), it can obtain good mechanical properties, such as high strength, hardness and certain toughness.
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AISI 1045 / DIN C45 1.0503 / JIS S45C / BS 080M40 carbon steel is a versatile medium-carbon structural steel widely recognized across global industries for its balanced mechanical properties and adaptability to heat treatment. Compliant with international standards including ASTM A29 (USA), EN 10083-2 (Europe), JIS G4051 (Japan), BS 970 (UK), and GB/T 699 (China, equivalent to 45# steel), this grade serves as a go-to solution for applications requiring a combination of high strength, moderate toughness, and cost-effectiveness.
At its core, this steel features a carbon content range of 0.42-0.50% —a key attribute that enables significant property enhancement through heat treatment (e.g., normalizing, quenching, and tempering). After proper processing, it achieves tensile strengths ranging from 630-850 Mpa and yield strengths of 370-490 Mpa Min, making it suitable for load-bearing components in machinery, automotive, and construction sectors. Unlike low-carbon steels (e.g., AISI 1020) that lack strength, or high-carbon steels (e.g., AISI 1060) that are overly brittle, AISI 1045/C45 steel strikes a critical balance, explaining its widespread adoption in general engineering and manufacturing.
The chemical makeup of AISI 1045 / DIN C45 1.0503 / JIS S45C / BS 080M40 steel is tightly controlled to ensure consistent performance across global equivalents. Key elements and their ranges (per respective standards) include:
Carbon (C): 0.42-0.50% (drives strength and hardenability)
Manganese (Mn): 0.50-0.90% (enhances toughness and reduces brittleness)
Silicon (Si): 0.15-0.40% Max (improves heat resistance and deoxidation)
Phosphorus (P): 0.030-0.050% Max (minimized to avoid reduced ductility)
Sulfur (S): 0.035-0.050% Max (controlled to prevent cracking during forging)
Chromium (Cr) & Molybdenum (Mo): 0.10-0.40% Max (trace elements in some standards to boost hardenability, e.g., DIN C45 allows up to 0.4% Cr).
This composition ensures the steel responds reliably to heat treatment while maintaining machinability for complex component manufacturing.
Mechanical performance varies by heat treatment and material size, with two primary conditions (per EN 10083-2) dominating industrial use:
Quenched & Tempered (QT) Condition:
Tensile strength: 630-850 Mpa (varies by size; e.g., ≤16mm diameter reaches 700-850 Mpa, while 40-100mm diameter ranges from 630-780 Mpa)
Yield strength: 370-490 Mpa Min (≤16mm diameter requires 490 Mpa Min, 40-100mm needs 370 Mpa Min)
Elongation: 14-17% Min (higher for larger sizes, e.g., 40-100mm diameter offers 17% Min)
Impact value: 12-25 J Min at room temperature (critical for load-bearing parts like shafts).
Normalized Condition:
Tensile strength: 560-620 Mpa (≤16mm diameter: 620 Mpa, >100mm diameter: 560 Mpa)
Yield strength: 275-340 Mpa Min (≤16mm diameter: 340 Mpa Min, >100mm diameter: 275 Mpa Min)
Elongation: 14-16% Min (suitable for non-critical structural parts).
DIN C45 1.0503 / AISI 1045 steel exhibits excellent hardenability, with surface hardness tailored to application needs via heat treatment:
Flame/Induction Hardening: Achieves a surface hardness of 55 HRC (ideal for wear-resistant parts like gear teeth).
Soft Annealing (+A): Reduces hardness to HB 207 Max (eases machining of complex components).
Quenched & Tempered (+QT): Typical hardness range of HRC 28-32 (balances strength and toughness for shafts and bolts).
Shearability Enhancement (+S): Limits hardness to HB 255 Max (optimizes cutting and forming processes).
For specialized requirements, restricted hardenability grades (+H, +HL, +HH) are available, with +HH grades maintaining 41-60 HRC at 4mm from the quenched end—critical for thick-section parts.
Hunan Qilu Steel offers AISI 1045/C45 steel in diverse forms to meet industrial needs, with standard sizes and tolerances including:
Cold Drawn Bars: Diameter Φ3-Φ80 mm, length 6000-9000 mm, tolerance +0/+0.1 mm (peeled/ground finish for precision).
Hot Rolled Bars: Diameter Φ16-Φ310 mm, length 6000-9000 mm, tolerance +0/+1 mm (black rolled finish for general use).
Hot Forged Bars: Diameter Φ100-Φ1200 mm, length 3000-5800 mm, tolerance +0/+5 mm (for heavy-duty components like crankshafts).
Hot Rolled Plates/Sheets: Thickness 3-200 mm, width 1500-2500 mm, length 2000-5800 mm, tolerance +0/+3 mm (milled/ground finish optional).
Straightness is controlled to 1 mm/1000 mm Max for cold-drawn bars and 3 mm/1000 mm Max for hot-rolled/forged products, ensuring ease of assembly.
Due to its medium carbon content (0.42-0.50%), AISI 1045/C45 steel has poor weldability compared to low-carbon grades. To avoid cracking and ensure joint integrity, critical precautions are required:
Preheating to 150-250℃ before welding (reduces thermal stress).
Using low-hydrogen electrodes (e.g., E7018) to minimize hydrogen-induced cracking.
Post-weld heat treatment (e.g., stress relieving at 550-650℃) to eliminate residual stresses.
Without these steps, welds may develop cold cracks or reduced fatigue resistance—making the steel unsuitable for high-stress welded applications unless properly processed.
AISI 1045/C45 steel is a staple in mechanical manufacturing, where its high strength and machinability make it ideal for:
Shafts: Transmission shafts, spindles, and pump shafts (benefit from 630-850 Mpa tensile strength and HRC 28-32 hardness).
Gears: Medium-load gears (flame-hardened to 55 HRC for wear resistance).
Fasteners: High-strength bolts, nuts, and studs (replace low-carbon options in load-bearing joints).
Connecting Rods: Engine and machinery connecting rods (balance of strength and toughness prevents bending under load).
In automotive production, this steel is used for critical components that demand durability:
Chassis Parts: Steering knuckles and half-shafts (withstand dynamic loads thanks to 370-490 Mpa yield strength).
Engine Components: Crankshafts and camshafts (quenched-tempered for fatigue resistance in high-speed operation).
Suspension Parts: Leaf spring brackets and control arms (adaptable to forging and machining).
For low-to-medium volume tooling, AISI 1045/C45 steel offers a cost-effective alternative to tool steels:
Simple Molds: Plastic injection molds and die-casting dies (soft-annealed for machining, then hardened for wear).
Cutting Tools: Drills, milling cutters, and punches (induction-hardened to 55 HRC for edge retention).
In construction and heavy machinery, the steel’s high strength supports structural integrity:
Structural Components: High-strength brackets, beams, and supports in bridges and industrial frames.
Anchors & Fasteners: Heavy-duty anchor bolts and foundation studs (resist pull-out forces in concrete).
Agricultural equipment relies on AISI 1045/C45 steel for its resistance to impact and wear:
Plow Blades: Hardened to withstand soil abrasion.
Harvester Parts: Drive shafts and gearboxes (tough enough to handle crop residue and vibration).
AISI 1045/DIN C45 1.0503 steel has direct equivalents in major global standards, including:
USA: AISI 1045 (per ASTM A29)
Europe: DIN C45 1.0503 (per EN 10083-2)
China: 45# steel (per GB/T 699)
UK: BS 080M40 (per BS 970)
Japan: JIS S45C (per JIS G4051).
These equivalents have nearly identical chemical compositions and mechanical properties, enabling cross-border substitution.
The carbon content of DIN C45 1.0503 steel is strictly controlled between 0.42-0.50%. This range is critical: too little carbon reduces strength, while too much increases brittleness. The medium carbon level is what allows the steel to be heat-treated for enhanced performance.
C45 steel responds well to three primary heat treatment processes:
Soft Annealing: Heat to 680-710℃, cool in furnace (reduces hardness to HB 207 Max for machining).
Normalizing: Heat to 840-880℃, cool in air (improves uniformity for structural parts).
Quenching & Tempering: Heat to 820-860℃, quench in water/oil, then temper at 550-660℃ (achieves HRC 28-32 and 630-850 Mpa tensile strength for load-bearing components).
Lower quenching temperatures (820-840℃) are used for water quenching, while higher temperatures (840-860℃) suit oil quenching.
Yes, but C45 steel has poor weldability due to its 0.42-0.50% carbon content. Key precautions include:
Preheating the base metal to 150-250℃ (reduces thermal shock).
Using low-hydrogen welding consumables (e.g., E7018 electrodes) to avoid hydrogen cracks.
Post-weld stress relieving at 550-650℃ (eliminates residual stresses).
Without these steps, welds may fail under load or develop cracks over time.
Surface hardness varies by process:
Flame/Induction Hardening: 55 HRC (wear-resistant surfaces).
Soft Annealing: HB 207 Max (machinable).
Quenched & Tempered: HRC 28-32 (balanced strength/toughness).
Shearability Enhancement (+S): HB 255 Max (easy cutting).
These values ensure the steel can be tailored to specific application needs, from machining to wear resistance.
Hunan Qilu Steel offers a wide range of supply sizes, including:
Cold Drawn Bars: Φ3-Φ80 mm (length 6000-9000 mm).
Hot Rolled Bars: Φ16-Φ310 mm (length 6000-9000 mm).
Hot Forged Bars: Φ100-Φ1200 mm (length 3000-5800 mm).
Hot Rolled Plates: 3-200 mm thick, 1500-2500 mm wide (length 2000-5800 mm).
Stock sizes are updated daily; contact our team for real-time availability.
C45 steel is popular in mechanical manufacturing for three key reasons:
Balanced Properties: Combines high tensile strength (630-850 Mpa) with moderate toughness, avoiding the brittleness of high-carbon steels.
Cost-Effectiveness: More affordable than alloy steels (e.g., AISI 4140) while meeting most medium-load requirements.
Heat Treatability: Easy to anneal, normalize, or quench-temper, enabling customization for diverse components (shafts, gears, bolts).
These attributes make it a cost-efficient solution for high-volume mechanical parts.
1: Steel equivalent
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-2 | GB/T699 | BS970 | JIS G4051 |
Grade | 1045 | C45/1.0503 | 45# | 080M40 | S45C |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr | Mo |
1045 | 0.43-0.50 | / | 0.60-0.90 | 0.040Max | 0.050Max | / | / |
C45/1.0503 | 0.42-0.50 | 0.4Max | 0.50-0.80 | 0.045Max | 0.045Max | 0.4Max | 0.1Max |
45# | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | 0.035Max | 0.035Max | 0.25Max | / |
080M40 | 0.36-0.44 | 0.10-0.40 | 0.60-1.00 | 0.050Max | 0.050Max | / | / |
S45C | 0.42-0.48 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.035Max | / | / |
3: Mechanical properties .
Mechanical properties for C45 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 | 700-850Mpa | 490Mpa Min | 14% Min | 35% Min | / |
16＜d≤40 8＜t≤20 | 650-800Mpa | 430Mpa Min | 16% Min | 40%Min | / |
40＜d≤100 20＜t≤60 | 630-780Mpa | 370Mpa Min | 17% Min | 45%Min | / |
Mechanical properties for C45 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 | 620Mpa | 340Mpa Min | 14% Min | / | / |
16＜d≤100 16＜t≤100 | 580Mpa | 305Mpa Min | 16% Min | / | / |
100＜d≤250 100＜t≤250 | 560Mpa | 275Mpa Min | 16% Min | / | / |
Sampling and preparation of test pieces for C45 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 C45 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 | 580Mpa Min | 305Mpa Min | 16% Min | / | / | / |
100＜d≤250 | 560Mpa Min | 275Mpa Min | 16% Min | 12% Min | 18J Min | 10J Min |
250＜d≤500 | 540Mpa Min | 240Mpa Min | 16% Min | 12% Min | 15J Min | 10J Min |
500＜d≤1000 | 530Mpa Min | 230Mpa Min | 15% Min | 11% Min | 12J Min | 10J Min |
Mechanical properties for C45 open die forgings steel in the quenched and tempered conditions according to EN10250-2.
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
d≤70 | 630Mpa Min | 370Mpa Min | 16% Min | / | 25J Min | / |
70＜d≤160 | 590Mpa Min | 340Mpa Min | 18% Min | 12% Min | 22J Min | 15J Min |
160＜d≤330 | 540Mpa Min | 320Mpa Min | 17% Min | 11% Min | 20J Min | 12J 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 |
Flame or Induction hardening | 55HRC |
Treated to improve shearability (+S) | HB255Max |
Soft annealed (+A) | HB207Max |
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 | |
Hardness In HRC + H | max | 62 | 61 | 61 | 60 | 57 | 51 | 44 | 37 | 34 | 33 | 32 | 31 | 30 |
min | 55 | 51 | 37 | 30 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | |
Hardness In HRC + HH | +HH4 | / | / | / | 41-60 | / | / | / | / | / | / | / | / | / |
+HH14 | 57-62 | / | / | 41-60 | / | / | / | / | / | / | / | / | / | |
Hardness In HRC + HL | +HL4 | / | / | / | 30-49 | / | / | / | / | / | / | / | / | / |
+HL14 | 55-60 | / | / | 30-49 | / | / | / | / | / | / | / | / | / | |
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 | 28 | 30 | 32 | 35 | 36 | 38 | 40 | 42 | 45 |
48 | 50 | 52 | 55 | 58 | 60 | 65 | 70 | 72 | 75 | 80 | 85 | 90 | 95 | 100 |
105 | 110 | 115 | 120 | 125 | 130 | 135 | 140 | 145 | 150 | 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 |
AISI 1045 / DIN C45 1.0503 / JIS S45C / BS 080M40 carbon steel is a versatile medium-carbon structural steel widely recognized across global industries for its balanced mechanical properties and adaptability to heat treatment. Compliant with international standards including ASTM A29 (USA), EN 10083-2 (Europe), JIS G4051 (Japan), BS 970 (UK), and GB/T 699 (China, equivalent to 45# steel), this grade serves as a go-to solution for applications requiring a combination of high strength, moderate toughness, and cost-effectiveness.
At its core, this steel features a carbon content range of 0.42-0.50% —a key attribute that enables significant property enhancement through heat treatment (e.g., normalizing, quenching, and tempering). After proper processing, it achieves tensile strengths ranging from 630-850 Mpa and yield strengths of 370-490 Mpa Min, making it suitable for load-bearing components in machinery, automotive, and construction sectors. Unlike low-carbon steels (e.g., AISI 1020) that lack strength, or high-carbon steels (e.g., AISI 1060) that are overly brittle, AISI 1045/C45 steel strikes a critical balance, explaining its widespread adoption in general engineering and manufacturing.
The chemical makeup of AISI 1045 / DIN C45 1.0503 / JIS S45C / BS 080M40 steel is tightly controlled to ensure consistent performance across global equivalents. Key elements and their ranges (per respective standards) include:
Carbon (C): 0.42-0.50% (drives strength and hardenability)
Manganese (Mn): 0.50-0.90% (enhances toughness and reduces brittleness)
Silicon (Si): 0.15-0.40% Max (improves heat resistance and deoxidation)
Phosphorus (P): 0.030-0.050% Max (minimized to avoid reduced ductility)
Sulfur (S): 0.035-0.050% Max (controlled to prevent cracking during forging)
Chromium (Cr) & Molybdenum (Mo): 0.10-0.40% Max (trace elements in some standards to boost hardenability, e.g., DIN C45 allows up to 0.4% Cr).
This composition ensures the steel responds reliably to heat treatment while maintaining machinability for complex component manufacturing.
Mechanical performance varies by heat treatment and material size, with two primary conditions (per EN 10083-2) dominating industrial use:
Quenched & Tempered (QT) Condition:
Tensile strength: 630-850 Mpa (varies by size; e.g., ≤16mm diameter reaches 700-850 Mpa, while 40-100mm diameter ranges from 630-780 Mpa)
Yield strength: 370-490 Mpa Min (≤16mm diameter requires 490 Mpa Min, 40-100mm needs 370 Mpa Min)
Elongation: 14-17% Min (higher for larger sizes, e.g., 40-100mm diameter offers 17% Min)
Impact value: 12-25 J Min at room temperature (critical for load-bearing parts like shafts).
Normalized Condition:
Tensile strength: 560-620 Mpa (≤16mm diameter: 620 Mpa, >100mm diameter: 560 Mpa)
Yield strength: 275-340 Mpa Min (≤16mm diameter: 340 Mpa Min, >100mm diameter: 275 Mpa Min)
Elongation: 14-16% Min (suitable for non-critical structural parts).
DIN C45 1.0503 / AISI 1045 steel exhibits excellent hardenability, with surface hardness tailored to application needs via heat treatment:
Flame/Induction Hardening: Achieves a surface hardness of 55 HRC (ideal for wear-resistant parts like gear teeth).
Soft Annealing (+A): Reduces hardness to HB 207 Max (eases machining of complex components).
Quenched & Tempered (+QT): Typical hardness range of HRC 28-32 (balances strength and toughness for shafts and bolts).
Shearability Enhancement (+S): Limits hardness to HB 255 Max (optimizes cutting and forming processes).
For specialized requirements, restricted hardenability grades (+H, +HL, +HH) are available, with +HH grades maintaining 41-60 HRC at 4mm from the quenched end—critical for thick-section parts.
Hunan Qilu Steel offers AISI 1045/C45 steel in diverse forms to meet industrial needs, with standard sizes and tolerances including:
Cold Drawn Bars: Diameter Φ3-Φ80 mm, length 6000-9000 mm, tolerance +0/+0.1 mm (peeled/ground finish for precision).
Hot Rolled Bars: Diameter Φ16-Φ310 mm, length 6000-9000 mm, tolerance +0/+1 mm (black rolled finish for general use).
Hot Forged Bars: Diameter Φ100-Φ1200 mm, length 3000-5800 mm, tolerance +0/+5 mm (for heavy-duty components like crankshafts).
Hot Rolled Plates/Sheets: Thickness 3-200 mm, width 1500-2500 mm, length 2000-5800 mm, tolerance +0/+3 mm (milled/ground finish optional).
Straightness is controlled to 1 mm/1000 mm Max for cold-drawn bars and 3 mm/1000 mm Max for hot-rolled/forged products, ensuring ease of assembly.
Due to its medium carbon content (0.42-0.50%), AISI 1045/C45 steel has poor weldability compared to low-carbon grades. To avoid cracking and ensure joint integrity, critical precautions are required:
Preheating to 150-250℃ before welding (reduces thermal stress).
Using low-hydrogen electrodes (e.g., E7018) to minimize hydrogen-induced cracking.
Post-weld heat treatment (e.g., stress relieving at 550-650℃) to eliminate residual stresses.
Without these steps, welds may develop cold cracks or reduced fatigue resistance—making the steel unsuitable for high-stress welded applications unless properly processed.
AISI 1045/C45 steel is a staple in mechanical manufacturing, where its high strength and machinability make it ideal for:
Shafts: Transmission shafts, spindles, and pump shafts (benefit from 630-850 Mpa tensile strength and HRC 28-32 hardness).
Gears: Medium-load gears (flame-hardened to 55 HRC for wear resistance).
Fasteners: High-strength bolts, nuts, and studs (replace low-carbon options in load-bearing joints).
Connecting Rods: Engine and machinery connecting rods (balance of strength and toughness prevents bending under load).
In automotive production, this steel is used for critical components that demand durability:
Chassis Parts: Steering knuckles and half-shafts (withstand dynamic loads thanks to 370-490 Mpa yield strength).
Engine Components: Crankshafts and camshafts (quenched-tempered for fatigue resistance in high-speed operation).
Suspension Parts: Leaf spring brackets and control arms (adaptable to forging and machining).
For low-to-medium volume tooling, AISI 1045/C45 steel offers a cost-effective alternative to tool steels:
Simple Molds: Plastic injection molds and die-casting dies (soft-annealed for machining, then hardened for wear).
Cutting Tools: Drills, milling cutters, and punches (induction-hardened to 55 HRC for edge retention).
In construction and heavy machinery, the steel’s high strength supports structural integrity:
Structural Components: High-strength brackets, beams, and supports in bridges and industrial frames.
Anchors & Fasteners: Heavy-duty anchor bolts and foundation studs (resist pull-out forces in concrete).
Agricultural equipment relies on AISI 1045/C45 steel for its resistance to impact and wear:
Plow Blades: Hardened to withstand soil abrasion.
Harvester Parts: Drive shafts and gearboxes (tough enough to handle crop residue and vibration).
AISI 1045/DIN C45 1.0503 steel has direct equivalents in major global standards, including:
USA: AISI 1045 (per ASTM A29)
Europe: DIN C45 1.0503 (per EN 10083-2)
China: 45# steel (per GB/T 699)
UK: BS 080M40 (per BS 970)
Japan: JIS S45C (per JIS G4051).
These equivalents have nearly identical chemical compositions and mechanical properties, enabling cross-border substitution.
The carbon content of DIN C45 1.0503 steel is strictly controlled between 0.42-0.50%. This range is critical: too little carbon reduces strength, while too much increases brittleness. The medium carbon level is what allows the steel to be heat-treated for enhanced performance.
C45 steel responds well to three primary heat treatment processes:
Soft Annealing: Heat to 680-710℃, cool in furnace (reduces hardness to HB 207 Max for machining).
Normalizing: Heat to 840-880℃, cool in air (improves uniformity for structural parts).
Quenching & Tempering: Heat to 820-860℃, quench in water/oil, then temper at 550-660℃ (achieves HRC 28-32 and 630-850 Mpa tensile strength for load-bearing components).
Lower quenching temperatures (820-840℃) are used for water quenching, while higher temperatures (840-860℃) suit oil quenching.
Yes, but C45 steel has poor weldability due to its 0.42-0.50% carbon content. Key precautions include:
Preheating the base metal to 150-250℃ (reduces thermal shock).
Using low-hydrogen welding consumables (e.g., E7018 electrodes) to avoid hydrogen cracks.
Post-weld stress relieving at 550-650℃ (eliminates residual stresses).
Without these steps, welds may fail under load or develop cracks over time.
Surface hardness varies by process:
Flame/Induction Hardening: 55 HRC (wear-resistant surfaces).
Soft Annealing: HB 207 Max (machinable).
Quenched & Tempered: HRC 28-32 (balanced strength/toughness).
Shearability Enhancement (+S): HB 255 Max (easy cutting).
These values ensure the steel can be tailored to specific application needs, from machining to wear resistance.
Hunan Qilu Steel offers a wide range of supply sizes, including:
Cold Drawn Bars: Φ3-Φ80 mm (length 6000-9000 mm).
Hot Rolled Bars: Φ16-Φ310 mm (length 6000-9000 mm).
Hot Forged Bars: Φ100-Φ1200 mm (length 3000-5800 mm).
Hot Rolled Plates: 3-200 mm thick, 1500-2500 mm wide (length 2000-5800 mm).
Stock sizes are updated daily; contact our team for real-time availability.
C45 steel is popular in mechanical manufacturing for three key reasons:
Balanced Properties: Combines high tensile strength (630-850 Mpa) with moderate toughness, avoiding the brittleness of high-carbon steels.
Cost-Effectiveness: More affordable than alloy steels (e.g., AISI 4140) while meeting most medium-load requirements.
Heat Treatability: Easy to anneal, normalize, or quench-temper, enabling customization for diverse components (shafts, gears, bolts).
These attributes make it a cost-efficient solution for high-volume mechanical parts.
1: Steel equivalent
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-2 | GB/T699 | BS970 | JIS G4051 |
Grade | 1045 | C45/1.0503 | 45# | 080M40 | S45C |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr | Mo |
1045 | 0.43-0.50 | / | 0.60-0.90 | 0.040Max | 0.050Max | / | / |
C45/1.0503 | 0.42-0.50 | 0.4Max | 0.50-0.80 | 0.045Max | 0.045Max | 0.4Max | 0.1Max |
45# | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | 0.035Max | 0.035Max | 0.25Max | / |
080M40 | 0.36-0.44 | 0.10-0.40 | 0.60-1.00 | 0.050Max | 0.050Max | / | / |
S45C | 0.42-0.48 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.035Max | / | / |
3: Mechanical properties .
Mechanical properties for C45 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 | 700-850Mpa | 490Mpa Min | 14% Min | 35% Min | / |
16＜d≤40 8＜t≤20 | 650-800Mpa | 430Mpa Min | 16% Min | 40%Min | / |
40＜d≤100 20＜t≤60 | 630-780Mpa | 370Mpa Min | 17% Min | 45%Min | / |
Mechanical properties for C45 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 | 620Mpa | 340Mpa Min | 14% Min | / | / |
16＜d≤100 16＜t≤100 | 580Mpa | 305Mpa Min | 16% Min | / | / |
100＜d≤250 100＜t≤250 | 560Mpa | 275Mpa Min | 16% Min | / | / |
Sampling and preparation of test pieces for C45 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 C45 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 | 580Mpa Min | 305Mpa Min | 16% Min | / | / | / |
100＜d≤250 | 560Mpa Min | 275Mpa Min | 16% Min | 12% Min | 18J Min | 10J Min |
250＜d≤500 | 540Mpa Min | 240Mpa Min | 16% Min | 12% Min | 15J Min | 10J Min |
500＜d≤1000 | 530Mpa Min | 230Mpa Min | 15% Min | 11% Min | 12J Min | 10J Min |
Mechanical properties for C45 open die forgings steel in the quenched and tempered conditions according to EN10250-2.
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
d≤70 | 630Mpa Min | 370Mpa Min | 16% Min | / | 25J Min | / |
70＜d≤160 | 590Mpa Min | 340Mpa Min | 18% Min | 12% Min | 22J Min | 15J Min |
160＜d≤330 | 540Mpa Min | 320Mpa Min | 17% Min | 11% Min | 20J Min | 12J 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 |
Flame or Induction hardening | 55HRC |
Treated to improve shearability (+S) | HB255Max |
Soft annealed (+A) | HB207Max |
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 | |
Hardness In HRC + H | max | 62 | 61 | 61 | 60 | 57 | 51 | 44 | 37 | 34 | 33 | 32 | 31 | 30 |
min | 55 | 51 | 37 | 30 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | |
Hardness In HRC + HH | +HH4 | / | / | / | 41-60 | / | / | / | / | / | / | / | / | / |
+HH14 | 57-62 | / | / | 41-60 | / | / | / | / | / | / | / | / | / | |
Hardness In HRC + HL | +HL4 | / | / | / | 30-49 | / | / | / | / | / | / | / | / | / |
+HL14 | 55-60 | / | / | 30-49 | / | / | / | / | / | / | / | / | / | |
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 | 28 | 30 | 32 | 35 | 36 | 38 | 40 | 42 | 45 |
48 | 50 | 52 | 55 | 58 | 60 | 65 | 70 | 72 | 75 | 80 | 85 | 90 | 95 | 100 |
105 | 110 | 115 | 120 | 125 | 130 | 135 | 140 | 145 | 150 | 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 |
