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1.7220 (34CrMo4) / SCM435 Alloy Steel Machining
When global engineering drawings call for DIN 1.7220 (34CrMo4) or JIS SCM435, they are specifying a premium Chromium-Molybdenum alloy steel designed for high tensile applications. Slightly lower in carbon than 4140, this grade offers an excellent balance of strength, toughness, and wear resistance, particularly after Quenching and Tempering (Q&T). At JUCHENG, we specialize in processing these specific international grades. Whether you need high-strength automotive fasteners, gas cylinder components, or power transmission shafts, we ensure the material properties meet the strict requirements of European and Japanese standards.
1.7220 Alloy Steel

JUCHENG's 1.7220/SCM435 Fabrication Capabilities

We provide specialized processing for high-stress components:
  • Precision Threading: Since SCM435 is the standard for high-strength bolts (Grade 10.9/12.9), we offer thread rolling and CNC single-point threading to ensure Class 3A/6g thread fits.
  • Heat Treatment (Q&T): We perform precise quenching and tempering to achieve the desired mechanical properties (typically 900-1100 MPa tensile strength) while maintaining toughness.
  • Hard Turning: For parts hardened after rough machining, we utilize CBN tooling to finish critical diameters to H6 tolerances without grinding.
  • Surface Protection: We provide Phosphate Coating (Parkerizing), Dacromet, or Zinc-Nickel plating, which are standard finishes for automotive fasteners made from this material.
CNC machined SCM435 steel

Advantages of CNC Machining 1.7220/SCM435

Advantage Detailed Description Key Benefit
High Static & Dynamic Strength Excellent response to heat treatment. Capable of withstanding heavy static loads and dynamic shocks (axles/bolts).
Superior Toughness Slightly better ductility and impact resistance than 4140 due to lower carbon. Reduces the risk of brittle failure in safety-critical parts like steering knuckles.
Consistent Hardenability The Cr-Mo content ensures uniform hardness penetration. Reliable mechanical properties throughout the cross-section of shafts and bolts.
Cold Formability In the annealed state, it has good plasticity. Suitable for parts requiring cold heading or upsetting before machining.
Wear Resistance Can be surface hardened (Induction/Nitriding). Extends the life of gears and splines.

Technical Parameters & Material Standards

We stock materials compliant with both European and Asian standards:
Grade Category Specification Characteristics & Ideal Uses
DIN 1.7220 / 34CrMo4 European Standard Characteristics: Chromium-Molybdenum tempering steel. High toughness in the QT condition. Widely used in the German automotive industry.
Uses: High-pressure gas cylinders, axle arms, connecting rods, pinions.
JIS SCM435 Japanese Standard Characteristics: The equivalent Japanese grade. The gold standard for high-strength bolts and automotive suspension parts.
Uses: Grade 10.9 / 12.9 Bolts, engine components, motorcycle frames.
Condition +QT Quenched & Tempered Characteristics: Heat treated to obtain high tensile strength (e.g., 900-1100 MPa) before or after machining.
Uses: Final functional parts ready for load.

CNC Machining Guidelines for SCM435

  • Machinability: In the annealed condition, machinability is good (similar to 4140). In the Q&T condition (approx. 30 HRC), it requires rigid setups and coated carbide tools.
  • Welding: Requires pre-heating (200-300°C) and post-weld stress relief to prevent cracking in the HAZ (Heat Affected Zone).
  • Distortion: Long shafts made from SCM435 can distort during heat treatment. We leave grinding allowance or use stress-relieved stock to mitigate this.
  • Induction Hardening: This material is excellent for induction hardening specific areas (like bearing journals) to 50-55 HRC while keeping the core tough.

Application Scenarios

  • Automotive: Cylinder head bolts, crankshafts, steering arms, stabilizers.
  • Fasteners: High-strength socket head cap screws (SHCS), studs, anchors.
  • Energy: Seamless gas cylinders (CNG tanks), pressure vessel necks.
  • Heavy Machinery: Drive shafts, conveyor pins, high-stress gears.

Physical Properties Table

Typical mechanical properties in Quenched & Tempered (+QT) condition:
Property 1.7220 / SCM435 (+QT) 1045 Carbon Steel Unit
Density 7.85 7.87 g/cm³
Tensile Strength 900 - 1100 570 - 700 MPa
Yield Strength 650 - 900 310 - 450 MPa
Elongation 10 - 14 16 %
Hardness 28 - 34 HRC 170 - 210 HB -
Impact Energy (KV) > 35 Low Joules
 
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    Factory Address :
    Shenzhen: Fourth Industrial Zone, Xisha Road, Shajing Street, Baoan District, Shenzhen.
    Dongguan: Building 5 and 4, No. 198, Chang'an Section, Guanchang Road, Chang'an Town, Dongguan.
     
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