Chrome Plated EN8 Rod (Q & T + I.H.)

The Chrome Plated EN8 Rod (Q & T + I.H.) is produced from premium EN8 medium carbon steel (080M40 / C40), processed with dual heat treatment—Quenched & Tempered plus Induction Hardened—followed by precision grinding and hard chrome plating. Q&T treatment gives the core a balanced matrix of 220–310 HB with good strength and toughness, while induction hardening produces a wear-resistant surface layer of 50–60 HRC at a controlled depth of 0.5–3.5 mm. Topped with an 850–1150 HV hard chrome deposit, this rod features a “tough core, hard surface” gradient structure, delivering excellent load-bearing capacity and wear resistance. It is designed for medium-to-high-pressure heavy-duty hydraulic cylinders, construction machinery, mining equipment and heavy-duty applications—the most comprehensive piston rod solution in the EN8 series.

• 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: Quenched & Tempered + Induction Hardened; customization options: Q&T only, I.H. only, QPQ, etc.

• Core Hardness (Q&T): 220–310 HB

• Surface Hardness (I.H.): 50–60 HRC

• 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: Fair (medium carbon content; welding on the induction-hardened zone should be avoided; pre-weld machining to remove the hardened layer and strict preheating and post-weld stress relieving are mandatory)

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

• Dual heat treatment creates an ideal “tough core + hard surface” gradient, combining good bending, impact and wear resistance

• Q&T core at 220–310 HB provides reliable overall mechanical properties for medium-to-high-pressure heavy-duty applications

• Induction-hardened surface at 50–60 HRC with adjustable depth offers strong wear and indentation resistance

• Hard chrome overlay (850–1150 HV) adds a second wear-resistant shield, significantly prolonging seal and rod life

• Tight f7 tolerance and low ovality ensure smooth motion and reliable sealing even under heavy loads

• 96-hour salt spray rating 9, combined corrosion protection for harsh environments

• Fully customizable dimensions, hardness profiles and processing to deliver balanced, enhanced solutions for OEMs

In addition to standard specifications, we offer:

• Custom diameters and lengths, including extra-large sizes

• Tolerance grades and non-standard OD tolerances

• Higher straightness upon request

• Tailored combination of core hardness and induction-hardened case hardness

• Precise control of hardening depth

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

• Extra-thick chrome layers beyond 100 μm

• 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.