| Quantity: | |
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4135
Qilu
Product Description
Hot forged and hot rolled 4135 round bar supplied in annealed or QT condition, 20 mm to 400 mm diameter, with heat treatment and rough machining done in our own workshop.
Equivalent to: AISI / SAE 4135 · DIN 34Cr4 (1.7033) · JIS SCr435 · GB 35CrMo · SCM435
ASTM 4135 Steel in Stock
Supply form — Round bar (flats on request)
Process — Hot forged / hot rolled
Condition — Annealed, or QT to 22–34 HRC
Diameter range — 20–400 mm
Standard — ASTM A29
Certificate — EN 10204 3.1 standard, 3.2 on request
Lead time — 15–30 days
4135 is a low-alloy chromium-molybdenum steel from ASTM A29. The 0.8–1.1 % chromium gives it through-hardenability beyond plain carbon steel, while molybdenum raises the high-temperature strength and resists temper embrittlement. It sits between 4130 and 4140 in carbon content, giving a useful balance of strength, toughness and weldability for medium-stress parts.
| Grade | C | Mn | Si | P | S | Cr | Mo |
| 4135 | 0.33–0.38 | 0.70–0.90 | 0.15–0.30 | 0.035Max | 0.040Max | 0.80–1.10 | 0.15–0.25 |
Typical values for the QT condition at medium section. We quench and temper to your drawing spec and verify on test pieces taken from the actual heat.
| Property | Annealed | QT |
| Tensile strength, Rm (MPa) | ≤ 570 | 780–980 |
| Yield strength, Re (MPa) | ≤ 295 | ≥ 590 |
| Elongation, A5 (%) | ≥ 22 | ≥ 14 |
| Impact, KV (J) | ≥ 50 | ≥ 40 |
| Hardness (HB) | ≤ 174 | 248–302 |
| Standard | Grade |
| ASTM / SAE (USA) | 4135 |
| DIN (Germany) | 34Cr4 / 1.7033 |
| JIS (Japan) | SCr435 |
| GB (China) | 35CrMo / SCM435 |
| BS (UK) | 708A37 |
| EN (Europe) | 34CrMo4 / 1.7220 |
Machinery — crankshafts, gears, pinions and shafts
Oil & gas — drill collars, tool joints, subs
Automotive — axle shafts, steering components
Fasteners — high-strength bolts and studs
4135 is normally oil-quenched from 840–870 °C and tempered between 540–680 °C depending on the strength/toughness balance required. For large sections water quenching with care is possible. If your drawing specifies a hardness range, tell us the working section — achievable core hardness depends on diameter and we will propose the exact cycle.
Most suppliers in this business are traders who subcontract everything. We run our own processes, which means shorter cycles and one point of accountability when something needs fixing.
Heat treatment shop — quenching and tempering to your target hardness, with furnace charts recorded per batch
Machining shop — rough turning, peeling and cutting to length, so your bar arrives ready for finish machining
Testing — ultrasonic per ASTM A388 / EN 10228-3, hardness mapping across the section, tensile and impact testing
Certification — EN 10204 3.1 as standard, 3.2 available with third-party witness (ABS, BV, CCS, GL)
Export packing — bundled, end-capped and rust-protected for sea freight
A1: 4135 has 0.33–0.38 % carbon versus 0.38–0.43 % for 4140, so 4140 reaches slightly higher strength in the same section. For most medium-stress shafting 4135 is more economical and easier to weld; for maximum tensile service 4140 is preferred. See our AISI 4140 alloy steel round bar page.
A2: Yes. We heat treat in our own shop and verify hardness at multiple points across the bar section. Tell us the required hardness range with the working diameter, because achievable core hardness depends on section size.
A3: EN 10204 3.1 mill certificate is included as standard, showing full heat analysis and mechanical test results. If you need 3.2 certification we arrange third-party inspection with ABS, BV, CCS or GL.
Send us your diameter, length, quantity, required hardness and destination port. You will get a quotation with the full technical proposal within 24 hours.
