Chrome Plated 42CrMo Rod (Q & T + I.H.)

The Chrome Plated 42CrMo Rod (Q & T + I.H.) is manufactured from premium 42CrMo chromium-molybdenum alloy steel (AISI 4140 / 42CrMo4) using a dual heat treatment—Quenched & Tempered plus Induction Hardened—followed by precision grinding and hard chrome plating. Q&T develops an ultra-strong, tough core at 260–340 HB, while induction hardening creates an extreme surface hardness of 55–65 HRC at a depth of 0.5–3.5 mm, further enhanced by an 850–1150 HV hard chrome deposit. The chromium and molybdenum combination delivers hardenability, fatigue strength and high-temperature resistance far beyond standard alloy steels, creating a supreme gradient of “ultra-tough core + ultra-hard surface”. This flagship rod is engineered for the most severe ultra-high-pressure, extreme heavy-load and heavy-abrasion applications—such as large mining supports, deep-sea equipment, and super-heavy construction machinery.

• 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): 260–340 HB

• Surface Hardness (I.H.): 55–65 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: Very poor (high carbon equivalent; welding directly on the hardened layer or HAZ is strictly prohibited; if unavoidable, the hardened layer must be mechanically removed beforehand, with strict high-temperature preheating and immediate post-weld stress-relief tempering; welding in load-bearing areas is absolutely forbidden)

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

• 42CrMo chromium-molybdenum steel with dual heat treatment creates a “super-tough core + ultra-hard surface” ultimate gradient

• Q&T core at 260–340 HB delivers unmatched bending, impact and ultra-high fatigue life

• Induction-hardened surface at 55–65 HRC with adjustable depth provides extreme wear and indentation resistance

• Hard chrome overlay (850–1150 HV) acts as a third defensive layer, offering comprehensive ultimate protection for extreme conditions

• Tight f7 tolerance and low ovality ensure flawless sealing and smooth operation under extreme pressure and heavy loads

• 96-hour salt spray rating 9, combined anti-corrosion system withstands harsh challenges like salt spray, acidic mine water, etc.

• Fully customizable in all dimensions to provide exclusive extreme-performance piston rods for world-class heavy-duty OEM equipment

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.