English 
T: +86-0731-85185770
E: enquiry@qilumetal.com
E: enquiry@qilumetal.com
No. 18 Xiangfu Middle Road,Yuhua District, Changsha City
 |
36CrNiMo4 / 1.6511 is a high-strength alloy steel that belongs to the European standard EN 10083-3 and EN 10250-3. It is widely used in various industries, including heavy machinery, automotive, aerospace, and energy sectors, due to its excellent mechanical properties. You can find its equivalent steel grades in different country standards, such as ASTM 4340 from the American standard ASTM A29/A29M, SNCM439/SNCM8 from the Japanese standard JIS G4105, 40CrNi2MoA from the Chinese standard GB/T 3077, and 817M40/EN 24 from the British standard BS 970.
36CrNiMo4 is part of the Cr-Ni-Mo steel series, with a carbon content ranging from 0.32% to 0.40%. After undergoing quenching and tempering (QT) heat treatment, it achieves exceptional comprehensive mechanical properties, including high tensile strength, excellent toughness, and good fatigue resistance. This makes it particularly suitable for applications requiring high load-bearing capacity and durability, such as gears, shafts, and other critical components in heavy-duty machinery. It is also known as a high-grade quenched and tempered steel.
| Quantity: | |
|---|---|
The chemical makeup of AISI 4340 / DIN 36CrNiMo4 1.6511 is strictly controlled to ensure uniform mechanical properties across every batch. Below is the detailed composition range for key grades, with critical values bolded for clarity:
Grade | C | Si | Mn | P (Max) | S (Max) | Cr | Mo | Ni |
AISI 4340 | 0.38–0.43 | 0.15–0.35 | 0.60–0.80 | 0.035 | 0.040 | 0.7–0.9 | 0.20–0.30 | 1.65–2.00 |
DIN 36CrNiMo4 1.6511 | 0.32–0.40 | ≤0.40 | 0.50–0.80 | 0.035 | 0.035 | 0.9–1.2 | 0.15–0.30 | 0.90–1.20 |
BS EN24 (817M40) | 0.35–0.45 | 0.10–0.35 | 0.45–0.70 | 0.050 | 0.050 | 0.9–1.4 | 0.20–0.35 | 1.30–1.80 |
This precision minimizes material variability, ensuring components meet strict industry standards (e.g., aerospace ASTM F2881, automotive ISO 683-15) and perform reliably in high-stress scenarios.
After quenching (820–860°C) and tempering (540–680°C), AISI 4340 / DIN 36CrNiMo4 exhibits outstanding comprehensive mechanical properties, tailored to section size. The table below outlines minimum values per EN 10250-3 for open-die forgings:
Size Range | Tensile Strength (Min) | Yield Strength (Min) | Elongation (Min, Longitudinal) | Impact Value (Min, RT, Longitudinal) |
d ≤ 160mm | 750MPa | 550MPa | 14% | 45J |
160mm ＜ d ≤ 330mm | 700MPa | 500MPa | 15% | 45J |
330mm ＜ d ≤ 660mm | 650MPa | 450MPa | 16% | 40J |
Notably, transverse properties (e.g., elongation ≥10% for d ≤ 160mm) remain strong, making the alloy suitable for components with complex load directions (e.g., crankshafts, gear shafts).
AISI 4340 / DIN 36CrNiMo4 offers excellent hardenability, meaning it retains hardness evenly across thick sections—critical for large components like wind turbine shafts. Its surface hardness can be adjusted via heat treatment to match application needs:
Flame/Induction Hardening: Achieves 54–62 HRC for wear-prone surfaces (e.g., gear teeth).
Soft Annealing (+A): Reduces hardness to ≤217 HB for easy machining.
Machinability Enhancement (+S): Limits hardness to ≤250 HB to optimize cutting tool life.
Quenched & Tempered (+QT): Common range of 28–32 HRC for a balance of strength and ductility.
For applications requiring controlled hardenability, three grades are available:
+H (Normal Hardenability): 1.5mm from quenched end → 51–59 HRC; 50mm → 33–49 HRC.
+HH (High Hardenability): 1.5mm → 54–59 HRC; 50mm → 38–49 HRC.
+HL (Low Hardenability): 1.5mm → 51–56 HRC; 50mm → 33–44 HRC.
To meet diverse customer needs, Hunan Qilu Steel supplies AISI 4340 / DIN 36CrNiMo4 in multiple forms with strict dimensional control:
Product Type | Size Range | Length Range | Surface Finish & Tolerance |
Hot Rolled Bar | Φ16–Φ310mm | 6000–9000mm | Black Rolled (+0/+1mm); Peeled (+0/+0.1mm) |
Hot Forged Bar | Φ100–Φ1200mm | 3000–5800mm | Black Forged (+0/+5mm); Turned/Milled (+0/+3mm) |
Hot Rolled Plate | Thickness: 3–200mm; Width: 1500–2500mm | 2000–5800mm | Grinding/Polished (+0/+0.05mm) for precision parts |
Hot Forged Block | Thickness: 80–800mm; Width: 100–2500mm | 2000–5800mm | Black Forged (+0/+5mm) for custom forging projects |
Additionally, straightness is guaranteed at ≤1mm/1000mm for precision-finished products (e.g., turned bars) and ≤3mm/1000mm for black 皮 (unfinished) materials—reducing post-processing time and costs.
AISI 4340 / DIN 36CrNiMo4 is the backbone of heavy machinery, where it powers critical components subjected to high loads and cyclic impacts:
Transmission Systems: Gears, drive shafts, and differential components for excavators, bulldozers, and cranes. Its high tensile strength (≥700MPa for mid-size sections) resists tooth wear and shaft bending.
Power Transmission: Crankshafts and connecting rods for diesel engines in mining trucks and agricultural machinery. The alloy’s fatigue resistance ensures long service life under repeated load cycles.
Structural Fasteners: High-strength bolts and nuts for assembling heavy frames, where its QT-induced hardness (28–32 HRC) prevents loosening under vibration.
In aerospace, material reliability is non-negotiable—and AISI 4340 / DIN 36CrNiMo4 meets strict aviation standards (e.g., AMS 6414):
Engine Parts: Turbine shafts and compressor disks, where its high-temperature stability (up to 300°C) and creep resistance maintain performance.
Defense Equipment: Armor plates and missile components, leveraging its high hardness (up to 62 HRC via induction hardening) for ballistic protection.
For high-performance and commercial vehicles, this alloy delivers durability under extreme torque and temperature:
Transmission Gears: Manual/automatic gearbox gears for sports cars and trucks. Its wear resistance (54–62 HRC post-hardening) extends gear life by 30% compared to standard 4140 steel.
Chassis Components: Drive shafts and suspension links for heavy-duty trucks. The alloy’s yield strength (≥500MPa for 160–330mm sections) resists deformation under heavy payloads.
Performance Engines: Camshafts and piston rods for racing engines, where its low carbon equivalent (CE ≤ 0.65) minimizes cracking during high-speed operation.
Renewable and traditional energy industries rely on AISI 4340 / DIN 36CrNiMo4 for components in harsh environments:
Wind Energy: Main shafts and gearbox internals for onshore/offshore wind turbines. The alloy’s fatigue resistance (10^7 cycles at 60% of tensile strength) withstands 20+ years of cyclic wind loads.
Oil & Gas: Drilling collars and downhole tools for deep-well exploration. Its corrosion resistance (aided by Cr and Mo) and high strength (≥650MPa for large sections) endure high pressure and abrasive fluids.
Power Generation: Turbine shafts for thermal power plants, where its heat resistance (up to 350°C post-tempering) maintains performance in high-temperature steam.
For molds requiring both strength and wear resistance, this alloy is an ideal choice:
Stamping Dies: Blanking and forming dies for metal sheets. Its surface hardness (54–62 HRC) resists galling and extends die life by 50% vs. mild steel.
Forging Dies: Hot forging dies for aluminum and steel components. The alloy’s toughness (≥40J impact value) prevents cracking during repeated hammer strikes.
AISI 4340 and DIN 36CrNiMo4 1.6511 have direct equivalents in major global standards to ensure compatibility across projects:
United States (ASTM A29/A29M): AISI 4340
Europe (EN 10083-3): DIN 36CrNiMo4 (1.6511)
China (GB/T 3077): 40CrNi2MoA
United Kingdom (BS 970): 817M40 / EN24
Japan (JIS G4105): SNCM439 / SNCM8
These equivalents share similar chemical compositions and mechanical properties, making them interchangeable for most applications (e.g., AISI 4340 and SNCM439 both have 1.65–2.00% Ni).
The alloy’s performance is optimized via three key heat treatment processes, each tailored to specific goals:
Soft Annealing (+A): Heat to 650–700°C, hold for 2–4 hours (depending on section size), then cool slowly in the furnace. This reduces hardness to ≤217 HB for easy machining (e.g., drilling, milling).
Normalization (+N): Heat to 850–880°C, hold for 1–2 hours, then cool in air. This refines grain structure and improves uniformity—ideal for prepping large forgings before QT.
Quenching & Tempering (QT): Heat to 820–860°C (use the lower end for water quenching, upper end for oil quenching), hold until fully austenitized, quench in water/oil, then temper at 540–680°C (1–3 hours) and air cool. This delivers the alloy’s signature high strength (≥750MPa) and toughness (≥45J).
While technically weldable, AISI 4340 / DIN 36CrNiMo4 has poor weldability due to its carbon content (0.32%–0.43%), which exceeds the 0.25% threshold where weld cracking risk rises. To ensure successful welding:
Preheat the base material to 200–300°C to reduce thermal stress.
Use low-hydrogen welding consumables (e.g., E11018-G electrodes for SMAW, ER110S-G for GMAW) to minimize hydrogen-induced cracking.
Perform post-weld heat treatment (PWHT): Temper at 600–650°C for 1–2 hours, then cool slowly. This relieves residual stress and restores ductility.
Avoid welding thick sections (＞50mm) without preheating, as this increases the risk of cold cracking.
Hunan Qilu Steel maintains monthly stock of 10,000+ tons of AISI 4340 / DIN 36CrNiMo4 in hot rolled bars, forged bars, and plates to support quick delivery. Common stock sizes include:
Hot Rolled Bars: Φ18, 20, 22, 25, 28, 30, 32, 35, 40, 45, 50–240mm (length 6–9m).
Hot Forged Bars: Φ100, 120, 150, 200–1200mm (length 3–5.8m).
Plates: 10, 15, 20, 25–200mm thick (width 1.5–2.5m, length 2–5.8m).
Stock levels change daily due to order volume, so contact our sales team via +86-15084978853 or enquiry@qilumetal.com for real-time availability.
A 200mm-diameter DIN 36CrNiMo4 forging (within the 160mm ＜ d ≤ 330mm size range) will meet the following minimum mechanical properties after QT treatment (per EN 10250-3):
Tensile Strength: ≥700MPa
Yield Strength: ≥500MPa
Elongation (Longitudinal): ≥15%; (Transverse): ≥11%
Impact Value (Room Temperature, Longitudinal): ≥45J; (Transverse): ≥22J
Hardness (QT): 28–32 HRC (typical; can be adjusted via tempering temperature).
These properties make it suitable for mid-size components like gear shafts, crane hooks, and wind turbine intermediate shafts.
1: Steel equivalent
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-3 | GB/T3077 | BS970 | JIS G4105 |
Grade | 4340 | 36CrNiMo4/1.6511 | 40CrNi2MoA | 817M40/EN24 | SNCM439 |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr | Mo | Ni |
4340 | 0.38-0.43 | 0.15-0.35 | 0.60-0.80 | 0.035Max | 0.040Max | 0.7-0.9 | 0.20-0.30 | 1.65-2.00 |
36CrNiMo4/1.6511 | 0.32-0.40 | 0.4Max | 0.50-0.80 | 0.035Max | 0.035Max | 0.9-1.2 | 0.15-0.30 | 0.90-1.20 |
40CrNi2MoA | 0.38-0.43 | 0.17-0.37 | 0.60-0.80 | 0.030Max | 0.030Max | 0.7-0.9 | 0.20-0.30 | 1.65-2.00 |
EN24 | 0.35-0.45 | 0.10-0.35 | 0.45-0.70 | 0.050Max | 0.050Max | 0.9-1.4 | 0.20-0.35 | 1.30-1.80 |
SNCM439 | 0.36-0.43 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.030Max | 0.6-1.0 | 0.15-0.30 | 1.60-2.00 |
3: Mechanical properties .
Mechanical properties for 36CrNiMo4 open die forgings steel according to EN10250-3
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
d≤160 | 750Mpa Min | 550Mpa Min | 14% Min | 10% Min | 45J Min | 22J Min |
160＜d≤330 | 700Mpa Min | 500Mpa Min | 15% Min | 11% Min | 45J Min | 22J Min |
330＜d≤660 | 650Mpa Min | 450Mpa Min | 16% Min | 12% Min | 40J Min | 20J 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 | 54-62HRC |
Treated to improve shearability (+S) | HB250Max |
Soft annealed (+A) | HB217Max |
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 | 1.5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | |
Hardness In HRC + H | max | 59 | 59 | 58 | 58 | 57 | 57 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 |
min | 51 | 50 | 49 | 49 | 48 | 47 | 46 | 45 | 43 | 41 | 39 | 38 | 36 | 34 | 33 | |
Hardness In HRC + HH | max | 59 | 59 | 58 | 58 | 57 | 57 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 |
min | 54 | 53 | 52 | 52 | 51 | 50 | 50 | 49 | 47 | 45 | 44 | 43 | 41 | 39 | 38 | |
Hardness In HRC + HL | max | 56 | 56 | 55 | 55 | 54 | 54 | 53 | 52 | 51 | 50 | 48 | 47 | 46 | 45 | 44 |
min | 51 | 50 | 49 | 49 | 48 | 47 | 46 | 45 | 43 | 41 | 39 | 38 | 36 | 34 | 33 | |
Scatter bands for the Rockwell - C hardness in the end quench hardenability test.
5: Supply size & Tolerance & Stock size
Product type | Size range | Length |
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.
18 | 20 | 22 | 25 | 28 | 30 | 32 | 35 | 40 | 45 | 50 | 55 | 57 | 60 | 65 |
70 | 75 | 80 | 85 | 90 | 95 | 100 | 105 | 110 | 115 | 120 | 125 | 130 | 135 | 140 |
150 | 160 | 170 | 180 | 190 | 200 | 210 | 220 | 230 | 240 |
The chemical makeup of AISI 4340 / DIN 36CrNiMo4 1.6511 is strictly controlled to ensure uniform mechanical properties across every batch. Below is the detailed composition range for key grades, with critical values bolded for clarity:
Grade | C | Si | Mn | P (Max) | S (Max) | Cr | Mo | Ni |
AISI 4340 | 0.38–0.43 | 0.15–0.35 | 0.60–0.80 | 0.035 | 0.040 | 0.7–0.9 | 0.20–0.30 | 1.65–2.00 |
DIN 36CrNiMo4 1.6511 | 0.32–0.40 | ≤0.40 | 0.50–0.80 | 0.035 | 0.035 | 0.9–1.2 | 0.15–0.30 | 0.90–1.20 |
BS EN24 (817M40) | 0.35–0.45 | 0.10–0.35 | 0.45–0.70 | 0.050 | 0.050 | 0.9–1.4 | 0.20–0.35 | 1.30–1.80 |
This precision minimizes material variability, ensuring components meet strict industry standards (e.g., aerospace ASTM F2881, automotive ISO 683-15) and perform reliably in high-stress scenarios.
After quenching (820–860°C) and tempering (540–680°C), AISI 4340 / DIN 36CrNiMo4 exhibits outstanding comprehensive mechanical properties, tailored to section size. The table below outlines minimum values per EN 10250-3 for open-die forgings:
Size Range | Tensile Strength (Min) | Yield Strength (Min) | Elongation (Min, Longitudinal) | Impact Value (Min, RT, Longitudinal) |
d ≤ 160mm | 750MPa | 550MPa | 14% | 45J |
160mm ＜ d ≤ 330mm | 700MPa | 500MPa | 15% | 45J |
330mm ＜ d ≤ 660mm | 650MPa | 450MPa | 16% | 40J |
Notably, transverse properties (e.g., elongation ≥10% for d ≤ 160mm) remain strong, making the alloy suitable for components with complex load directions (e.g., crankshafts, gear shafts).
AISI 4340 / DIN 36CrNiMo4 offers excellent hardenability, meaning it retains hardness evenly across thick sections—critical for large components like wind turbine shafts. Its surface hardness can be adjusted via heat treatment to match application needs:
Flame/Induction Hardening: Achieves 54–62 HRC for wear-prone surfaces (e.g., gear teeth).
Soft Annealing (+A): Reduces hardness to ≤217 HB for easy machining.
Machinability Enhancement (+S): Limits hardness to ≤250 HB to optimize cutting tool life.
Quenched & Tempered (+QT): Common range of 28–32 HRC for a balance of strength and ductility.
For applications requiring controlled hardenability, three grades are available:
+H (Normal Hardenability): 1.5mm from quenched end → 51–59 HRC; 50mm → 33–49 HRC.
+HH (High Hardenability): 1.5mm → 54–59 HRC; 50mm → 38–49 HRC.
+HL (Low Hardenability): 1.5mm → 51–56 HRC; 50mm → 33–44 HRC.
To meet diverse customer needs, Hunan Qilu Steel supplies AISI 4340 / DIN 36CrNiMo4 in multiple forms with strict dimensional control:
Product Type | Size Range | Length Range | Surface Finish & Tolerance |
Hot Rolled Bar | Φ16–Φ310mm | 6000–9000mm | Black Rolled (+0/+1mm); Peeled (+0/+0.1mm) |
Hot Forged Bar | Φ100–Φ1200mm | 3000–5800mm | Black Forged (+0/+5mm); Turned/Milled (+0/+3mm) |
Hot Rolled Plate | Thickness: 3–200mm; Width: 1500–2500mm | 2000–5800mm | Grinding/Polished (+0/+0.05mm) for precision parts |
Hot Forged Block | Thickness: 80–800mm; Width: 100–2500mm | 2000–5800mm | Black Forged (+0/+5mm) for custom forging projects |
Additionally, straightness is guaranteed at ≤1mm/1000mm for precision-finished products (e.g., turned bars) and ≤3mm/1000mm for black 皮 (unfinished) materials—reducing post-processing time and costs.
AISI 4340 / DIN 36CrNiMo4 is the backbone of heavy machinery, where it powers critical components subjected to high loads and cyclic impacts:
Transmission Systems: Gears, drive shafts, and differential components for excavators, bulldozers, and cranes. Its high tensile strength (≥700MPa for mid-size sections) resists tooth wear and shaft bending.
Power Transmission: Crankshafts and connecting rods for diesel engines in mining trucks and agricultural machinery. The alloy’s fatigue resistance ensures long service life under repeated load cycles.
Structural Fasteners: High-strength bolts and nuts for assembling heavy frames, where its QT-induced hardness (28–32 HRC) prevents loosening under vibration.
In aerospace, material reliability is non-negotiable—and AISI 4340 / DIN 36CrNiMo4 meets strict aviation standards (e.g., AMS 6414):
Engine Parts: Turbine shafts and compressor disks, where its high-temperature stability (up to 300°C) and creep resistance maintain performance.
Defense Equipment: Armor plates and missile components, leveraging its high hardness (up to 62 HRC via induction hardening) for ballistic protection.
For high-performance and commercial vehicles, this alloy delivers durability under extreme torque and temperature:
Transmission Gears: Manual/automatic gearbox gears for sports cars and trucks. Its wear resistance (54–62 HRC post-hardening) extends gear life by 30% compared to standard 4140 steel.
Chassis Components: Drive shafts and suspension links for heavy-duty trucks. The alloy’s yield strength (≥500MPa for 160–330mm sections) resists deformation under heavy payloads.
Performance Engines: Camshafts and piston rods for racing engines, where its low carbon equivalent (CE ≤ 0.65) minimizes cracking during high-speed operation.
Renewable and traditional energy industries rely on AISI 4340 / DIN 36CrNiMo4 for components in harsh environments:
Wind Energy: Main shafts and gearbox internals for onshore/offshore wind turbines. The alloy’s fatigue resistance (10^7 cycles at 60% of tensile strength) withstands 20+ years of cyclic wind loads.
Oil & Gas: Drilling collars and downhole tools for deep-well exploration. Its corrosion resistance (aided by Cr and Mo) and high strength (≥650MPa for large sections) endure high pressure and abrasive fluids.
Power Generation: Turbine shafts for thermal power plants, where its heat resistance (up to 350°C post-tempering) maintains performance in high-temperature steam.
For molds requiring both strength and wear resistance, this alloy is an ideal choice:
Stamping Dies: Blanking and forming dies for metal sheets. Its surface hardness (54–62 HRC) resists galling and extends die life by 50% vs. mild steel.
Forging Dies: Hot forging dies for aluminum and steel components. The alloy’s toughness (≥40J impact value) prevents cracking during repeated hammer strikes.
AISI 4340 and DIN 36CrNiMo4 1.6511 have direct equivalents in major global standards to ensure compatibility across projects:
United States (ASTM A29/A29M): AISI 4340
Europe (EN 10083-3): DIN 36CrNiMo4 (1.6511)
China (GB/T 3077): 40CrNi2MoA
United Kingdom (BS 970): 817M40 / EN24
Japan (JIS G4105): SNCM439 / SNCM8
These equivalents share similar chemical compositions and mechanical properties, making them interchangeable for most applications (e.g., AISI 4340 and SNCM439 both have 1.65–2.00% Ni).
The alloy’s performance is optimized via three key heat treatment processes, each tailored to specific goals:
Soft Annealing (+A): Heat to 650–700°C, hold for 2–4 hours (depending on section size), then cool slowly in the furnace. This reduces hardness to ≤217 HB for easy machining (e.g., drilling, milling).
Normalization (+N): Heat to 850–880°C, hold for 1–2 hours, then cool in air. This refines grain structure and improves uniformity—ideal for prepping large forgings before QT.
Quenching & Tempering (QT): Heat to 820–860°C (use the lower end for water quenching, upper end for oil quenching), hold until fully austenitized, quench in water/oil, then temper at 540–680°C (1–3 hours) and air cool. This delivers the alloy’s signature high strength (≥750MPa) and toughness (≥45J).
While technically weldable, AISI 4340 / DIN 36CrNiMo4 has poor weldability due to its carbon content (0.32%–0.43%), which exceeds the 0.25% threshold where weld cracking risk rises. To ensure successful welding:
Preheat the base material to 200–300°C to reduce thermal stress.
Use low-hydrogen welding consumables (e.g., E11018-G electrodes for SMAW, ER110S-G for GMAW) to minimize hydrogen-induced cracking.
Perform post-weld heat treatment (PWHT): Temper at 600–650°C for 1–2 hours, then cool slowly. This relieves residual stress and restores ductility.
Avoid welding thick sections (＞50mm) without preheating, as this increases the risk of cold cracking.
Hunan Qilu Steel maintains monthly stock of 10,000+ tons of AISI 4340 / DIN 36CrNiMo4 in hot rolled bars, forged bars, and plates to support quick delivery. Common stock sizes include:
Hot Rolled Bars: Φ18, 20, 22, 25, 28, 30, 32, 35, 40, 45, 50–240mm (length 6–9m).
Hot Forged Bars: Φ100, 120, 150, 200–1200mm (length 3–5.8m).
Plates: 10, 15, 20, 25–200mm thick (width 1.5–2.5m, length 2–5.8m).
Stock levels change daily due to order volume, so contact our sales team via +86-15084978853 or enquiry@qilumetal.com for real-time availability.
A 200mm-diameter DIN 36CrNiMo4 forging (within the 160mm ＜ d ≤ 330mm size range) will meet the following minimum mechanical properties after QT treatment (per EN 10250-3):
Tensile Strength: ≥700MPa
Yield Strength: ≥500MPa
Elongation (Longitudinal): ≥15%; (Transverse): ≥11%
Impact Value (Room Temperature, Longitudinal): ≥45J; (Transverse): ≥22J
Hardness (QT): 28–32 HRC (typical; can be adjusted via tempering temperature).
These properties make it suitable for mid-size components like gear shafts, crane hooks, and wind turbine intermediate shafts.
1: Steel equivalent
Country | USA | Europe | China | British | Japan |
Standard | ASTM A29 | EN10083-3 | GB/T3077 | BS970 | JIS G4105 |
Grade | 4340 | 36CrNiMo4/1.6511 | 40CrNi2MoA | 817M40/EN24 | SNCM439 |
2: Chemical composition
Grade | C | Si | Mn | P | S | Cr | Mo | Ni |
4340 | 0.38-0.43 | 0.15-0.35 | 0.60-0.80 | 0.035Max | 0.040Max | 0.7-0.9 | 0.20-0.30 | 1.65-2.00 |
36CrNiMo4/1.6511 | 0.32-0.40 | 0.4Max | 0.50-0.80 | 0.035Max | 0.035Max | 0.9-1.2 | 0.15-0.30 | 0.90-1.20 |
40CrNi2MoA | 0.38-0.43 | 0.17-0.37 | 0.60-0.80 | 0.030Max | 0.030Max | 0.7-0.9 | 0.20-0.30 | 1.65-2.00 |
EN24 | 0.35-0.45 | 0.10-0.35 | 0.45-0.70 | 0.050Max | 0.050Max | 0.9-1.4 | 0.20-0.35 | 1.30-1.80 |
SNCM439 | 0.36-0.43 | 0.15-0.35 | 0.60-0.90 | 0.030Max | 0.030Max | 0.6-1.0 | 0.15-0.30 | 1.60-2.00 |
3: Mechanical properties .
Mechanical properties for 36CrNiMo4 open die forgings steel according to EN10250-3
Size range | Tensile strength | Yield strength | Alongation | Impact value at RT/J | ||
L | Tr | L | Tr | |||
d≤160 | 750Mpa Min | 550Mpa Min | 14% Min | 10% Min | 45J Min | 22J Min |
160＜d≤330 | 700Mpa Min | 500Mpa Min | 15% Min | 11% Min | 45J Min | 22J Min |
330＜d≤660 | 650Mpa Min | 450Mpa Min | 16% Min | 12% Min | 40J Min | 20J 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 | 54-62HRC |
Treated to improve shearability (+S) | HB250Max |
Soft annealed (+A) | HB217Max |
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 | 1.5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | |
Hardness In HRC + H | max | 59 | 59 | 58 | 58 | 57 | 57 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 |
min | 51 | 50 | 49 | 49 | 48 | 47 | 46 | 45 | 43 | 41 | 39 | 38 | 36 | 34 | 33 | |
Hardness In HRC + HH | max | 59 | 59 | 58 | 58 | 57 | 57 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 |
min | 54 | 53 | 52 | 52 | 51 | 50 | 50 | 49 | 47 | 45 | 44 | 43 | 41 | 39 | 38 | |
Hardness In HRC + HL | max | 56 | 56 | 55 | 55 | 54 | 54 | 53 | 52 | 51 | 50 | 48 | 47 | 46 | 45 | 44 |
min | 51 | 50 | 49 | 49 | 48 | 47 | 46 | 45 | 43 | 41 | 39 | 38 | 36 | 34 | 33 | |
Scatter bands for the Rockwell - C hardness in the end quench hardenability test.
5: Supply size & Tolerance & Stock size
Product type | Size range | Length |
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.
18 | 20 | 22 | 25 | 28 | 30 | 32 | 35 | 40 | 45 | 50 | 55 | 57 | 60 | 65 |
70 | 75 | 80 | 85 | 90 | 95 | 100 | 105 | 110 | 115 | 120 | 125 | 130 | 135 | 140 |
150 | 160 | 170 | 180 | 190 | 200 | 210 | 220 | 230 | 240 |
