Chrome Plated 40Cr Rod (Induction Hardened)

The Chrome Plated 40Cr Rod (Induction Hardened) is manufactured from premium 40Cr alloy structural steel (AISI 5140) in a non-heat-treated core condition. The surface is selectively hardened via induction hardening to produce a deep, high-hardness wear-resistant case, followed by precision grinding and hard chrome plating. With its chromium content, 40Cr offers improved hardenability over plain carbon steels, achieving higher and more uniform surface hardness after induction hardening, while the core retains good toughness and machinability. This “hard surface + tough core” gradient makes it ideal for medium-to-high-pressure hydraulic cylinders under severe wear and frequent reciprocation, construction machinery, mining equipment, and agricultural machinery—an optimal choice for extreme surface wear resistance balanced with cost control.

• Diameter: Mainly φ6–300 mm, larger custom sizes accepted

• Length: ≤8000 mm, custom lengths available

• Straightness: ≤0.2 mm/M

• Tolerance Grades: IT6–IT9

• OD Tolerance: According to ISO f7/f8/g6/h7/h8/h9; customized tolerances available upon request

• Ovality: Half of the tolerance value ISO f7

• Heat Treatment: Induction Hardened; customization options include combined Q&T or QPQ

• Core Hardness: ≤250 HB (approx. 200–250 HB), non-heat-treated

• Surface Hardness: 52–62 HRC (after induction hardening; alloy content ensures excellent hardness uniformity)

• Hardening Depth: 0.5–3.5 mm (adjustable)

• Surface Treatment: Hard Chrome Plated; customization options: EN Plating / Zinc Plating / Laser Cladding / Nitriding / QPQ / Thermal Spraying / Ceramic Coating

• Chrome Thickness: ≥10 μm, mainly 20–40 μm; can be over 100 μm for high-standard requirements

• Chrome Layer Hardness: 850–1150 HV (Vickers 100 gf)

• Surface Roughness: Ra≤0.2 μm, Rt≤2 μm

• Cohesion: No cracks, breaking or detaching after thermal shock (warming up at 300 ℃ and cooling in water)

• Porosity: Tested according to ISO 1456/1458, evaluation according to ISO 10289 rating 8–10. Under 10× magnification, no more than 30 micro white pin-holes per 1000 mm², with diameter not greater than approx. 0.1 mm

• Corrosion Resistance: Tested in neutral salt spray according to ISO 9227/ASTM B117 – 96 hours, rating 9 per ISO 10289

• Weldability: Poor (alloy elements reduce weldability compared to plain carbon steel; the hardened layer must be mechanically removed before welding, with strict preheating and post-weld stress relief; welding on load-bearing areas should be avoided)

• Packing: Anti-rust oil + cardboard tube/plastic sleeve + wooden case

• 40Cr alloy steel with good hardenability achieves 52–62 HRC after induction hardening for superior wear resistance

• Non-hardened core preserves toughness; adjustable case depth precisely matches wear conditions

• Hard chrome overlay (850–1150 HV) adds a second wear-resistant layer, dramatically extending seal and rod life

• Tight dimensional tolerances and low ovality ensure efficient sealing and smooth operation under heavy loads

• 96-hour salt spray rating 9 provides reliable rust protection in harsh industrial and outdoor environments

• Can be combined with Q&T or QPQ for more advanced core-surface property gradients to meet extreme requirements

In addition to standard specifications, we offer:

• Custom diameters and lengths, including large and extra-long sizes

• Tolerance grades and non-standard OD tolerances

• Higher straightness upon request

• Tailored hardening depth and surface hardness range

• Combined Quenched & Tempered treatment for higher core strength

• Surface treatment alternatives: zinc plating, electroless nickel, laser cladding, nitriding, thermal spray, ceramic coating

• Special chrome layer thickness

• Enhanced corrosion resistance and dedicated packing solutions

Limits and Fits Table

The table below provides shaft deviation values for commonly used tolerance grades f7, f8, g6, h7, h8, and h9 to assist your selection according to seal fits.

Chemical Composition

The table presents the standard chemical composition of frequently used materials such as CK45, 25Mn, 20#, ST52, 40Cr, 42CrMo4, 20MnV6 and 38MnVS6 for your reference.

Mechanical Properties

The following table lists reference tensile strength, yield strength, elongation and impact energy values for CK45 (hot-rolled, cold-drawn, Q&T), 25Mn, 20#, ST52, Q345D, 40Cr, 42CrMo4, 20MnV6 and 38MnVS6 under various conditions.