Chrome Plated 27SiMn Rod (Quenched & Tempered)

The Chrome Plated 27SiMn Rod (Quenched & Tempered) is manufactured from premium 27SiMn silicon-manganese alloy structural steel, processed with quenching and tempering (Q&T) followed by precision grinding and hard chrome plating. Through the combined strengthening of silicon and manganese, 27SiMn steel achieves high strength, high toughness and good wear resistance after Q&T, delivering outstanding comprehensive mechanical properties. A classic steel for hydraulic props, supports and heavy-duty cylinders, this rod is widely used in ultra-high-pressure, heavy-load and high-impact hydraulic cylinders for mining machinery, construction equipment and heavy-duty applications—an ideal solution for reliable load-bearing capacity and durability.

• 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; customization options include Induction Hardening and QPQ

• Core Hardness: 220–320 HB (typical hardness range for Q&T treated 27SiMn, can be optimized upon request)

• 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 (moderate to high carbon equivalent limits weldability; sufficient preheating and post-weld slow cooling with stress relieving are mandatory; welding in critical load-bearing areas is not recommended)

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

• Q&T treated 27SiMn silicon-manganese alloy steel with good hardenability delivers a core hardness of 220–320 HB with an excellent strength-toughness balance

• Outstanding bending, torsional and impact resistance, especially suited for ultra-high-pressure and high-impact cylinder applications

• Hard chrome layer at 850–1150 HV provides superior wear, scratch and corrosion resistance

• Tight f7 OD tolerance and minimal ovality ensure precise sealing and low-friction operation in high-pressure systems

• 96-hour salt spray test rated to class 9, meeting long-term corrosion protection in harsh mining, underground and outdoor environments

• Can be further enhanced with Induction Hardening or QPQ for a “high-strength tough core + ultra-hard surface” gradient

• Full customization provides a proven, mature silicon-manganese alloy steel piston rod solution for heavy-duty hydraulic equipment

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

• Adjustment and optimization of core hardness range

• Combined heat treatments such as Induction Hardening or QPQ

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

• Extra-thick chrome layers (can exceed 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.