WUXI PAZON TECHNOLOGY CO., LTD
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The Nitrocarburized C50 Rod features a QPQ-treated surface (diffusion zone 0.30–0.40 mm, white layer ≥25 µm) delivering ≥600 HV hardness without chrome plating. Available in φ6–300 mm, up to 8000 mm long, it meets ISO f7 tolerance and 120-hour salt spray rating 9. Built on C50 high-carbon steel with superior core strength, this chrome-free rod provides excellent wear and corrosion resistance for demanding hydraulic cylinders and outdoor equipment, with full customization supported.
PZPR0019
PAZON
The Nitrocarburized C50 Rod (C50 QPQ Rod) is precision-machined from premium C50 medium carbon steel (1.0540 / 50#) in a non-heat-treated condition (core hardness ≤250 HB) and treated with an advanced QPQ (Quench-Polish-Quench) nitrocarburizing process—consisting of nitriding, oxidation, polishing, and re-oxidation. This produces a dense white layer and a supportive diffusion zone without relying on chrome plating. With a higher carbon content than CK45, C50 steel offers greater core strength and after QPQ treatment delivers even better surface hardness and wear resistance. This chrome-free, environmentally compliant rod is ideally suited for medium-to-high-pressure hydraulic cylinders, construction machinery, agricultural equipment, marine systems and outdoor applications requiring high corrosion resistance and environmental compliance.
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
Core Condition & Hardness: Non-heat-treated (as-rolled/cold-drawn), core hardness ≤250 HB
Surface Modification Treatment: QPQ nitrocarburizing (Nitriding + Oxidation + Polishing + Re-oxidation)
Diffusion Layer Depth: 0.30–0.40 mm
White Layer (Compound Layer) Thickness: ≥25 μm
Surface Hardness: ≥600 HV (typical on white layer; with higher carbon content, ≥650 HV options available)
Surface Roughness: Ra≤0.2 μm, Rt≤2 μm (after polishing)
Corrosion Resistance: Tested in neutral salt spray per ISO 9227/ASTM B117 – 120 hours, rating 9 per ISO 10289
Weldability: Poor (high carbon content severely limits weldability; the QPQ layer must be mechanically removed from the weld zone prior to welding, with strict preheating and post-weld stress relief; welding on load-bearing areas should be avoided)
Packing: Anti-rust oil + cardboard tube/plastic sleeve + wooden case
Eco-friendly & chrome-free: QPQ process contains no hexavalent chromium, meeting RoHS and environmental directives
Higher surface hardness: thanks to C50’s higher carbon content, the white layer exceeds 600 HV with an option for ≥650 HV
Superior corrosion resistance: 120-hour salt spray rating 9, matching or exceeding hard chrome performance
Higher core strength: C50 base material provides greater strength than CK45 even in the non-heat-treated condition
Excellent dimensional stability: low processing temperature ensures minimal distortion for precision rods
No delamination risk: the compound and diffusion layers are metallurgically bonded, eliminating peeling concerns
Low friction coefficient: QPQ surface has self-lubricating properties, reducing seal wear and improving cylinder efficiency
Fully customizable: wide choice of dimensions, tolerances, core conditions and alternative surface treatments
In addition to the standard QPQ finish, we offer:
Custom diameters and lengths, including extra-long or oversized rods
Tolerance grades and non-standard OD tolerances
Higher straightness upon request
Quenched & Tempered core for increased mechanical strength
Alternative surface treatments: hard chrome plating, electroless nickel, zinc plating, laser cladding, thermal spray, ceramic coating
Special case depth requirements or selective nitriding protection
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.
Limits and Fits Table | ||||||||||||
Diameter | f7 | f8 | g6 | h7 | h8 | h9 | ||||||
es | ei | es | ei | es | ei | es | ei | es | ei | es | ei | |
>6-10 | -0.013 | -0.028 | -0.013 | -0.035 | -0.005 | -0.014 | 0 | -0.015 | 0 | -0.022 | 0 | -0.036 |
>10-18 | -0.016 | -0.034 | -0.016 | -0.043 | -0.006 | -0.017 | 0 | -0.018 | 0 | -0.027 | 0 | -0.043 |
>18-30 | -0.020 | -0.041 | -0.020 | -0.053 | -0.007 | -0.020 | 0 | -0.021 | 0 | -0.033 | 0 | -0.052 |
>30-50 | -0.025 | -0.050 | -0.025 | -0.064 | -0.009 | -0.025 | 0 | -0.025 | 0 | -0.039 | 0 | -0.062 |
>50-80 | -0.030 | -0.060 | -0.030 | -0.076 | -0.010 | -0.029 | 0 | -0.030 | 0 | -0.046 | 0 | -0.074 |
>80-120 | -0.036 | -0.071 | -0.036 | -0.090 | -0.012 | -0.034 | 0 | -0.035 | 0 | -0.054 | 0 | -0.087 |
>120-180 | -0.043 | -0.083 | -0.043 | -0.106 | -0.014 | -0.039 | 0 | -0.040 | 0 | -0.063 | 0 | -0.100 |
>180-250 | -0.050 | -0.096 | -0.050 | -0.122 | -0.015 | -0.044 | 0 | -0.046 | 0 | -0.072 | 0 | -0.115 |
>250-315 | -0.056 | -0.108 | -0.056 | -0.137 | -0.017 | -0.049 | 0 | -0.052 | 0 | -0.081 | 0 | -0.130 |
>315-400 | -0.062 | -0.119 | -0.062 | -0.151 | -0.018 | -0.054 | 0 | -0.057 | 0 | -0.089 | 0 | -0.140 |
>400-500 | -0.068 | -0.131 | -0.068 | -0.165 | -0.020 | -0.060 | 0 | -0.063 | 0 | -0.097 | 0 | -0.155 |
>500-630 | -0.076 | -0.146 | -0.076 | -0.186 | -0.022 | -0.066 | 0 | -0.070 | 0 | -0.110 | 0 | -0.175 |
>630-800 | -0.080 | -0.160 | -0.080 | -0.205 | -0.024 | -0.074 | 0 | -0.080 | 0 | -0.125 | 0 | -0.200 |
>800-1000 | -0.086 | -0.176 | -0.086 | -0.226 | -0.026 | -0.082 | 0 | -0.090 | 0 | -0.140 | 0 | -0.230 |
>1000-1250 | -0.098 | -0.203 | -0.098 | -0.263 | -0.028 | -0.094 | 0 | -0.105 | 0 | -0.165 | 0 | -0.260 |
>1250-1600 | -0.110 | -0.235 | -0.110 | -0.305 | -0.030 | -0.108 | 0 | -0.125 | 0 | -0.185 | 0 | -0.290 |
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.
Chemical Composition | ||||||||||
Material | C(%) | Si(%) | Mn(%) | P(%) | S(%) | V(%) | Ni(%) | Cr(%) | Mo(%) | Cu(%) |
CK45 | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.035 | ≤0.30 | ≤0.25 | ≤0.25 | ||
25Mn | 0.22-0.30 | 0.17-0.37 | 0.70-1.00 | ≤0.035 | ≤0.035 | ≤0.30 | ≤0.25 | ≤0.25 | ||
20# | 0.17-0.24 | 0.17-0.37 | 0.35-0.65 | ≤0.035 | ≤0.035 | ≤0.30 | ≤0.25 | ≤0.25 | ||
ST52 | ≤0.24 | ≤0.55 | ≤1.6 | ≤0.045 | ≤0.045 | 0.01-0.12 | ≤0.50 | ≤0.30 | ≤0.10 | ≤0.55 |
40Cr | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.035 | ≤0.30 | 0.80-1.10 | ≤0.30 | ||
42CrMo4 | 0.38-0.45 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.035 | 0.07-0.12 | ≤0.03 | 0.90-1.20 | 0.15-0.25 | ≤0.030 |
20MnV6 | 0.17-0.24 | 0.17-0.37 | 1.30-1.60 | ≤0.035 | ≤0.035 | 0.10-0.20 | ≤0.30 | ≤0.30 | ≤0.30 | |
38MnVS6 | 0.34-0.41 | ≤0.80 | 1.20-1.60 | ≤0.025 | 0.02-0.06 | 0.08-0.20 | ≤0.30 | ≤0.08 | ≤0.30 | |
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.
Mechanical Properties | |||||
Material | T.S | Y.S | E% | CHARPY | CONDITION |
CK45 | 610 | 355 | 15 | ＞41J | Normalised |
CK45 | 630 | 540 | 15 | ＞41J | Cold Drawn |
CK45 | 800 | 630 | 20 | ＞41J | Q+T |
25Mn | 620 | 520 | 15 | Cold Drawn | |
20# | 520 | 400 | 15 | Cold Drawn | |
ST52 | 500 | 355 | 22 | Normalised | |
Q345D | 620 | 520 | 15 | ＞27(-20°C) | Cold Drawn |
40Cr | 1000 | 800 | 10 | Q+T | |
42CrMo4 | 980 | 850 | 14 | ＞47J | Q+T |
20MnV6 | 750 | 590 | 12 | ＞40J | Normalised |
38MnVS6 | 850 | 580 | 15 | Normalised | |
