Chrome Plated CK45 Tube

The Chrome Plated CK45 Tube is precision-ground and hard chrome plated from premium CK45 medium carbon steel seamless tube in a non-heat-treated condition. Designed as a hollow piston rod or cylinder barrel tube, it maintains high outer diameter accuracy and surface performance while significantly reducing component weight. It can also serve as a fluid passage within hydraulic systems, offering a dual-function advantage. Widely used in construction machinery, injection molding machines, lightweight hydraulic equipment and cylinders requiring internal oil flow, it represents a proven solution for weight reduction and system simplification.

• Outer Diameter: Mainly φ25–300 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: None; customization options include Quenched & Tempered, Induction Hardening, and QPQ

• Core Hardness: ≤229 HB (approx. 190–230 HB)

• 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: Good (proper preheating and post-weld treatment are recommended)

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

• Hollow structure effectively reduces weight, lowering overall equipment load and energy consumption

• Can double as a hydraulic fluid passage, simplifying system design and saving space and piping costs

• Strict f7 OD tolerance and low ovality ensure precise sealing and smooth operation

• Hard chrome layer at 850–1150 HV provides reliable wear and corrosion resistance

• 96-hour salt spray rating 9 meets corrosion protection requirements for typical industrial and outdoor environments

• Full customization of wall thickness, inner bore, heat treatment and surface finishing to meet OEM specifications

• A cost-effective, non-heat-treated chrome plated tube delivering high performance for standard medium/low-pressure applications

In addition to standard specifications, we offer:

• Custom OD, ID and wall thickness

• Custom lengths

• Tolerance grades and non-standard OD tolerances

• Higher straightness and internal bore precision requirements

• Heat treatment options: Q&T, Induction Hardening, QPQ

• 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.