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Grade: AISI 1045
Equivalent Steel: GB 45#, JIS S45C, EN C45/1.0503, BS 080M40
AISI 1045, widely known by its European equivalent C45 (1.0503) and Japanese counterpart S45C, is a classic medium-carbon steel defined by its carefully balanced chemical composition. Its performance is driven by a controlled carbon content of 0.43% to 0.50%, which provides the essential base strength and allows for significant hardening through heat treatment. Manganese, present at 0.60% to 0.90%, acts as a crucial strengthener and deoxidizer, enhancing the steel's toughness and hardenability.
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1045
Qilu
AISI 1045 is a globally recognized medium carbon structural steel with a carbon content strictly controlled at 0.42-0.50%, belonging to the European standards EN 10083-2 and EN 10250-2. 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). As a core material in general engineering, it fills the performance gap between low-carbon steels (e.g., AISI 1020) with insufficient strength and high-carbon steels (e.g., AISI 1060) with excessive brittleness, and offers a more economical solution than alloy steels (e.g., AISI 4140) for medium-load scenarios.
After professional heat treatment (normalizing, quenching & tempering, flame/induction hardening), this steel achieves a tensile strength of 560-850 Mpa and a yield strength of 275-490 Mpa, while retaining moderate toughness and machinability. It is widely used in machine building, automotive manufacturing, tool & mold making, construction, and agricultural machinery industries, and is the first choice for load-bearing components such as shafts, gears, fasteners, and crankshafts.
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-2 | GB/T699 | BS970 | JIS G4051 |
Grade | 1045 | C45/1.0503 | 45# | 080M40 | S45C |
The chemical components of AISI 1045 and its global equivalents are precisely controlled to ensure stable heat treatment response and machinability. Trace elements such as chromium (Cr) are added in partial standards to further optimize hardenability. The following is the component range of each grade:
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 | / | / |
The mechanical properties of C45 steel are highly dependent on heat treatment process and material size (diameter/thickness). The following are the key performance indicators specified by EN 10083-2 (the main European standard), and the performance of open die forgings complies with EN 10250-2.
The most commonly used heat treatment state for industrial load-bearing parts, with balanced strength, toughness and fatigue resistance:
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 | / |
Suitable for structural components with low load requirements, with good processability and uniformity:
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 | / | / |
For large forged components (e.g., crankshafts, heavy-duty brackets), the performance indicators of longitudinal (L) and transverse (Tr) directions are differentiated, and the impact value is an important test index:
Normalized/Tempered: For d≤1000mm forgings, tensile strength ≥530Mpa, longitudinal elongation ≥15%.
Quenched & Tempered: For d≤330mm forgings, tensile strength ≥540Mpa, room temperature impact value ≥12J (transverse).
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
AISI 1045 steel has excellent hardenability, and the surface hardness can be customized according to application scenarios through different heat treatment processes, realizing the matching of "hard surface and tough core" for wear-resistant and load-bearing parts. For special thick-section components, restricted hardenability grades (+H, +HL, +HH) are available to ensure uniform hardness of the workpiece.
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) |
+H Grade: At 15mm from the quenched end, the hardness is 30 HRC (max) / 20 HRC (min), suitable for general precision parts.
+HH Grade: Maintains 41-60 HRC at 4mm from the quenched end, the best choice for thick-section wear-resistant parts.
+HL Grade: 30-49 HRC at 4mm from the quenched end, balanced hardenability for medium-thickness components.
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.
Hunan Qilu Steel provides AISI 1045 steel in multiple forms (cold drawn bar, hot rolled bar, hot forged bar, hot rolled plate) to meet the processing needs of different industries, with strict control of straightness and dimensional tolerance to ensure assembly precision. Stock sizes are updated daily, with monthly stock of hot rolled/forged bars exceeding 10,000 tons.
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. | |||||
Hot Rolled Bar: Φ16-310mm (stock for Φ16, 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, 310mm)
Hot Forged Bar: Φ310-550mm (stock for Φ310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550mm)
Due to the medium carbon content (0.43-0.50%), AISI 1045 steel has poor weldability compared with low-carbon steels (carbon content ＜0.25%). Direct welding will cause cold cracks, reduced fatigue resistance and weld joint brittleness. Strict process precautions must be taken for welding applications, and it is not recommended for high-stress welded components (alloy steel is recommended for such scenarios).
Preheating Treatment: Preheat the base metal to 150-250℃ before welding to reduce thermal stress and avoid cold crack formation.
Welding Consumables: Use low-hydrogen electrodes (e.g., E7018) to minimize hydrogen-induced cracking in the weld zone.
Post-Weld Heat Treatment: Perform stress relieving at 550-650℃ after welding to eliminate residual stresses and restore the toughness of the weld joint.
Welding Process: Adopt small current and multi-layer welding to reduce the heat input of the base metal and avoid excessive grain growth.
AISI 1045 steel is a versatile structural steel with the characteristics of "customizable performance, wide processing adaptability and high cost performance", and is widely used in 5 major industries. Its performance can be precisely matched with component working conditions through heat treatment, realizing the optimal balance of performance and cost.
The first choice for medium-load mechanical components, relying on high strength and machinability:
Shaft Parts: Transmission shafts, spindles, pump shafts (QT state, HRC 28-32, tensile strength 630-850Mpa)
Gears: Medium-load gears (flame-hardened surface 55 HRC for wear resistance, tough core for impact resistance)
Fasteners: High-strength bolts, nuts, studs (replace low-carbon steel for load-bearing joints)
Connecting Rods: Engine/machinery connecting rods (balanced strength-toughness to prevent bending under dynamic load)
Critical components requiring durability and fatigue resistance:
Chassis Parts: Steering knuckles, half-shafts (withstand dynamic road loads, yield strength ≥370Mpa)
Engine Components: Crankshafts, camshafts (QT state for high-speed operation fatigue resistance)
Suspension Parts: Leaf spring brackets, control arms (adaptable to forging and precision machining)
Ideal for low-to-medium volume tooling, replacing expensive special tool steels:
Simple Molds: Plastic injection molds, die-casting dies (soft annealing for machining, surface hardening for wear resistance)
Cutting Tools: Drills, milling cutters, punches (induction hardening to 55 HRC for edge retention)
High-strength structural components for large-scale engineering:
Structural Parts: High-strength brackets, beams, supports (bridges, industrial frames, heavy machinery frames)
Anchors & Fasteners: Heavy-duty anchor bolts, foundation studs (resist concrete pull-out forces, high tensile strength)
Wear-resistant and impact-resistant components for harsh working conditions:
Plow Blades: Surface-hardened to withstand soil abrasion and impact
Harvester Parts: Drive shafts, gearboxes (tough enough to handle crop residue friction and vibration)
Customers often compare AISI 1045 with low-carbon steel (AISI 1020), high-carbon steel (AISI 1060) and alloy steel (AISI 4140) when selecting materials. The following is a detailed performance and application comparison to help quickly determine the most suitable material:
| Steel Grade | Carbon Content | Core Advantages | Core Disadvantages | Tensile Strength (Mpa) | Typical Application |
| AISI 1045 | 0.43-0.50% | Balanced strength-toughness, excellent heat treatability, cost-effective | Poor weldability | 560-850 (QT) | Medium-load shafts, gears, fasteners, forgings |
| AISI 1020 | 0.17-0.23% | Excellent weldability, good machinability, low cost | Low strength, poor hardenability | 350-450 | Low-load structural parts, welded components, cold-formed parts |
| AISI 1060 | 0.55-0.65% | High surface hardness after hardening, good wear resistance | High brittleness, poor toughness, difficult machining | 600-900 | Wear-resistant parts (springs, blades, cutting tools) |
| AISI 4140 | 0.38-0.43% (alloy steel) | High strength, good toughness, excellent hardenability, weldable (after preheating) | High cost, complex heat treatment | 750-1000 (QT) | High-stress components (automotive axles, hydraulic parts, mold cores) |
Choose AISI 1020 if the component requires welding as the main process and low load.
Choose AISI 1045 for medium-load, non-welded components that require both strength and toughness (the most cost-effective choice).
Choose AISI 1060 only for pure wear-resistant, low-impact parts (note brittleness control).
Choose AISI 4140 for high-stress, complex working conditions components (acceptable for high cost).
A1: This is the golden range for medium carbon steel:
Less than 0.42% will lead to insufficient strength and poor hardenability
More than 0.50% will significantly increase brittleness, reduce toughness and machinability, and increase the risk of forging/welding cracking.
A2: Three core processes, with strict temperature control for different purposes:
Soft Annealing: 680-710℃ heating, furnace cooling → HB 207 Max (for machining)
Normalizing: 840-880℃ heating, air cooling → uniform structure (for non-critical parts)
Quenching & Tempering: 820-860℃ heating (water quenching 820-840℃, oil quenching 840-860℃), 550-660℃ tempering → HRC 28-32 (for load-bearing parts)
A3: The machinability of C45 steel is highly dependent on its heat treatment condition, and efficiency can be maximized by selecting the right process:
Soft Annealing State (HB 207 Max): The best machinability, suitable for complex CNC machining, drilling and milling.
QT State (HRC 28-32): Moderate machinability, need to use hard alloy cutting tools for turning and grinding.
Optimization Tip: Perform soft annealing before complex machining, and then conduct QT/surface hardening to ensure both machining efficiency and final performance.
A4: Choose 1045 steel for medium-load, non-extreme working conditions (e.g., general shafts, medium-load gears, fasteners) — it can meet performance requirements and reduce material cost by 30-50% compared with AISI 4140. Choose AISI 4140 only for high-stress, high-fatigue components (e.g., automotive axles, hydraulic cylinders).
Inquire Now: Get the latest quotation, stock status and technical parameters.
AISI 1045 is a globally recognized medium carbon structural steel with a carbon content strictly controlled at 0.42-0.50%, belonging to the European standards EN 10083-2 and EN 10250-2. 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). As a core material in general engineering, it fills the performance gap between low-carbon steels (e.g., AISI 1020) with insufficient strength and high-carbon steels (e.g., AISI 1060) with excessive brittleness, and offers a more economical solution than alloy steels (e.g., AISI 4140) for medium-load scenarios.
After professional heat treatment (normalizing, quenching & tempering, flame/induction hardening), this steel achieves a tensile strength of 560-850 Mpa and a yield strength of 275-490 Mpa, while retaining moderate toughness and machinability. It is widely used in machine building, automotive manufacturing, tool & mold making, construction, and agricultural machinery industries, and is the first choice for load-bearing components such as shafts, gears, fasteners, and crankshafts.
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-2 | GB/T699 | BS970 | JIS G4051 |
Grade | 1045 | C45/1.0503 | 45# | 080M40 | S45C |
The chemical components of AISI 1045 and its global equivalents are precisely controlled to ensure stable heat treatment response and machinability. Trace elements such as chromium (Cr) are added in partial standards to further optimize hardenability. The following is the component range of each grade:
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 | / | / |
The mechanical properties of C45 steel are highly dependent on heat treatment process and material size (diameter/thickness). The following are the key performance indicators specified by EN 10083-2 (the main European standard), and the performance of open die forgings complies with EN 10250-2.
The most commonly used heat treatment state for industrial load-bearing parts, with balanced strength, toughness and fatigue resistance:
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 | / |
Suitable for structural components with low load requirements, with good processability and uniformity:
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 | / | / |
For large forged components (e.g., crankshafts, heavy-duty brackets), the performance indicators of longitudinal (L) and transverse (Tr) directions are differentiated, and the impact value is an important test index:
Normalized/Tempered: For d≤1000mm forgings, tensile strength ≥530Mpa, longitudinal elongation ≥15%.
Quenched & Tempered: For d≤330mm forgings, tensile strength ≥540Mpa, room temperature impact value ≥12J (transverse).
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
AISI 1045 steel has excellent hardenability, and the surface hardness can be customized according to application scenarios through different heat treatment processes, realizing the matching of "hard surface and tough core" for wear-resistant and load-bearing parts. For special thick-section components, restricted hardenability grades (+H, +HL, +HH) are available to ensure uniform hardness of the workpiece.
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) |
+H Grade: At 15mm from the quenched end, the hardness is 30 HRC (max) / 20 HRC (min), suitable for general precision parts.
+HH Grade: Maintains 41-60 HRC at 4mm from the quenched end, the best choice for thick-section wear-resistant parts.
+HL Grade: 30-49 HRC at 4mm from the quenched end, balanced hardenability for medium-thickness components.
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.
Hunan Qilu Steel provides AISI 1045 steel in multiple forms (cold drawn bar, hot rolled bar, hot forged bar, hot rolled plate) to meet the processing needs of different industries, with strict control of straightness and dimensional tolerance to ensure assembly precision. Stock sizes are updated daily, with monthly stock of hot rolled/forged bars exceeding 10,000 tons.
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. | |||||
Hot Rolled Bar: Φ16-310mm (stock for Φ16, 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, 310mm)
Hot Forged Bar: Φ310-550mm (stock for Φ310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550mm)
Due to the medium carbon content (0.43-0.50%), AISI 1045 steel has poor weldability compared with low-carbon steels (carbon content ＜0.25%). Direct welding will cause cold cracks, reduced fatigue resistance and weld joint brittleness. Strict process precautions must be taken for welding applications, and it is not recommended for high-stress welded components (alloy steel is recommended for such scenarios).
Preheating Treatment: Preheat the base metal to 150-250℃ before welding to reduce thermal stress and avoid cold crack formation.
Welding Consumables: Use low-hydrogen electrodes (e.g., E7018) to minimize hydrogen-induced cracking in the weld zone.
Post-Weld Heat Treatment: Perform stress relieving at 550-650℃ after welding to eliminate residual stresses and restore the toughness of the weld joint.
Welding Process: Adopt small current and multi-layer welding to reduce the heat input of the base metal and avoid excessive grain growth.
AISI 1045 steel is a versatile structural steel with the characteristics of "customizable performance, wide processing adaptability and high cost performance", and is widely used in 5 major industries. Its performance can be precisely matched with component working conditions through heat treatment, realizing the optimal balance of performance and cost.
The first choice for medium-load mechanical components, relying on high strength and machinability:
Shaft Parts: Transmission shafts, spindles, pump shafts (QT state, HRC 28-32, tensile strength 630-850Mpa)
Gears: Medium-load gears (flame-hardened surface 55 HRC for wear resistance, tough core for impact resistance)
Fasteners: High-strength bolts, nuts, studs (replace low-carbon steel for load-bearing joints)
Connecting Rods: Engine/machinery connecting rods (balanced strength-toughness to prevent bending under dynamic load)
Critical components requiring durability and fatigue resistance:
Chassis Parts: Steering knuckles, half-shafts (withstand dynamic road loads, yield strength ≥370Mpa)
Engine Components: Crankshafts, camshafts (QT state for high-speed operation fatigue resistance)
Suspension Parts: Leaf spring brackets, control arms (adaptable to forging and precision machining)
Ideal for low-to-medium volume tooling, replacing expensive special tool steels:
Simple Molds: Plastic injection molds, die-casting dies (soft annealing for machining, surface hardening for wear resistance)
Cutting Tools: Drills, milling cutters, punches (induction hardening to 55 HRC for edge retention)
High-strength structural components for large-scale engineering:
Structural Parts: High-strength brackets, beams, supports (bridges, industrial frames, heavy machinery frames)
Anchors & Fasteners: Heavy-duty anchor bolts, foundation studs (resist concrete pull-out forces, high tensile strength)
Wear-resistant and impact-resistant components for harsh working conditions:
Plow Blades: Surface-hardened to withstand soil abrasion and impact
Harvester Parts: Drive shafts, gearboxes (tough enough to handle crop residue friction and vibration)
Customers often compare AISI 1045 with low-carbon steel (AISI 1020), high-carbon steel (AISI 1060) and alloy steel (AISI 4140) when selecting materials. The following is a detailed performance and application comparison to help quickly determine the most suitable material:
| Steel Grade | Carbon Content | Core Advantages | Core Disadvantages | Tensile Strength (Mpa) | Typical Application |
| AISI 1045 | 0.43-0.50% | Balanced strength-toughness, excellent heat treatability, cost-effective | Poor weldability | 560-850 (QT) | Medium-load shafts, gears, fasteners, forgings |
| AISI 1020 | 0.17-0.23% | Excellent weldability, good machinability, low cost | Low strength, poor hardenability | 350-450 | Low-load structural parts, welded components, cold-formed parts |
| AISI 1060 | 0.55-0.65% | High surface hardness after hardening, good wear resistance | High brittleness, poor toughness, difficult machining | 600-900 | Wear-resistant parts (springs, blades, cutting tools) |
| AISI 4140 | 0.38-0.43% (alloy steel) | High strength, good toughness, excellent hardenability, weldable (after preheating) | High cost, complex heat treatment | 750-1000 (QT) | High-stress components (automotive axles, hydraulic parts, mold cores) |
Choose AISI 1020 if the component requires welding as the main process and low load.
Choose AISI 1045 for medium-load, non-welded components that require both strength and toughness (the most cost-effective choice).
Choose AISI 1060 only for pure wear-resistant, low-impact parts (note brittleness control).
Choose AISI 4140 for high-stress, complex working conditions components (acceptable for high cost).
A1: This is the golden range for medium carbon steel:
Less than 0.42% will lead to insufficient strength and poor hardenability
More than 0.50% will significantly increase brittleness, reduce toughness and machinability, and increase the risk of forging/welding cracking.
A2: Three core processes, with strict temperature control for different purposes:
Soft Annealing: 680-710℃ heating, furnace cooling → HB 207 Max (for machining)
Normalizing: 840-880℃ heating, air cooling → uniform structure (for non-critical parts)
Quenching & Tempering: 820-860℃ heating (water quenching 820-840℃, oil quenching 840-860℃), 550-660℃ tempering → HRC 28-32 (for load-bearing parts)
A3: The machinability of C45 steel is highly dependent on its heat treatment condition, and efficiency can be maximized by selecting the right process:
Soft Annealing State (HB 207 Max): The best machinability, suitable for complex CNC machining, drilling and milling.
QT State (HRC 28-32): Moderate machinability, need to use hard alloy cutting tools for turning and grinding.
Optimization Tip: Perform soft annealing before complex machining, and then conduct QT/surface hardening to ensure both machining efficiency and final performance.
A4: Choose 1045 steel for medium-load, non-extreme working conditions (e.g., general shafts, medium-load gears, fasteners) — it can meet performance requirements and reduce material cost by 30-50% compared with AISI 4140. Choose AISI 4140 only for high-stress, high-fatigue components (e.g., automotive axles, hydraulic cylinders).
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