Chrome Plated 42CrMo Rod (Quenched & Tempered)

The Chrome Plated 42CrMo Rod (Quenched & Tempered) is manufactured from premium 42CrMo chromium-molybdenum alloy steel (AISI 4140 / 42CrMo4), processed with quenching and tempering (Q&T) followed by precision grinding and hard chrome plating. Thanks to the combined addition of chromium and molybdenum, 42CrMo steel possesses exceptional hardenability, achieving a uniform combination of high strength and toughness throughout the cross-section after Q&T, along with excellent fatigue and high-temperature resistance. This rod is engineered for ultra-high-pressure, heavy-load and high-fatigue applications such as large mining hydraulic supports, heavy construction machinery, marine hydraulic systems and heavy forging equipment—an upgrade solution for extreme loads and maximum reliability.

• 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: 260–340 HB (typical hardness range for Q&T treated 42CrMo, 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: Poor (high carbon equivalent; welding without proper preheating and post-heating is prohibited; if necessary, a dedicated welding procedure must be strictly followed, with immediate post-weld stress relieving recommended; welding in critical load-bearing areas should be avoided)

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

• Q&T treated 42CrMo chromium-molybdenum alloy steel offers exceptional hardenability, with core hardness of 260–340 HB and superior overall mechanical properties

• Outstanding tensile, bending and fatigue resistance, designed specifically for extreme pulsating loads and impact conditions

• Hard chrome layer at 850–1150 HV provides excellent wear and corrosion protection

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

• 96-hour salt spray rating 9, suitable for highly corrosive environments such as marine, mining, and underground

• Can be further enhanced with Induction Hardening or QPQ for an “ultra-strong core + ultra-hard surface” extreme performance gradient

• Full customization delivers top-tier materials and process solutions for heavy-duty OEM 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

• Targeted optimization of core hardness range and mechanical properties

• 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.