HARD CHROME PLATED BAR AND TUBE
Chrome-plated bars and tubes are primarily used as piston rods. a critical component in hydraulic cylinders. They have the basic function of transforming hydraulic power into linear motion whilst preventing ingress of abrasive media into the hydraulic system – and this will stipulate a set of demands on a rod. Our steel grades are optimised in analysis and production to match the requirements in mechanical properties as well as amenability to our plating process. Prior to delivery, all Cromax products are controlled to ensure optimal micro-crack distribution with high crack density. These properties together with closely controlled pre-treatment, plating and finishing procedures, guarantee superior corrosion resistance. Ovakos quality assurance system includes a thorough final inspection of every single product as well as verification in salt-spray testing of all combinations of steel heat treatment. rolling operation and plating batch. When elevated corrosion resistance is required, Ovako offers Cromax C or NiKrom plating.
Advantages of Cromax and NiKrom
• In-house production facilitates deliver unmatched quality and consistency
• Optimsed to match the requirements in mechanical properties
• Every single production batch is verified in salt-spray testing
• High consistency and quality ensure well-functioning hydraulic systems
Abrasive wear on the rod due to contamination particles on both the outside and inside of the hydraulic system leads to direct oil leakage and secondary damage on the sealing system. This is unacceptable from an environmental and productivity point of view. The consistency in the Cromax process and our extensive quality control system ensures minimal variation in chrome thickness and hardness, which are the most significant parameters from this perspective. With the right surface roughness and structure as well as an optimised micro-crack distribution, Cromax products secures correct lubrication for the sealing system.
Standard and Cromax steel grades
| Selection Criteria | Technical Data | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Steel Grades | Machinability | Fusion welding | Friction Welding | High Impact Requirements | EUR/Mpa Index | Dimension DIA. (mm) | Yield strength R/R (MPa) | Tensile Strength Rm (MPa) | Elongation A5 (%) | Hardness HB | Impact toughness KV (J) | Surface hardness IH HRC |
| 180X | Good | Quite Suitable | Suitable | No | 90 | 20-90 | > 500 | 750-950 | 16 | 220-270 | - | > 50 |
| 280X | Good | Suitable | Suitable | Yes | 60 | 20-90 91-125 > 125 | > 520 > 440 > 350 | 650-800 550-700 500-700 | 19 19 19 | 200-241 180-230 180-230 | > 27 at -20°c > 27 at -20°c > 27 at -20°c | > 45 |
| 4821H | Rather Good | Needs Care | Suitable | No | 55 | < 125 | > 580 | 850-100 | 14 | 250-300 | - | > 55 |
| 42CrMo4 | Moderate | Unsuitable | Suitable | Yes | 70 | < 40 40-95 > 95 | > 750 > 690 > 550 | 1000-1200 900-1100 800-950 | 11 12 13 | 295-355 265-325 235-295 | > 35 at 20°c > 35 at 20°c > 35 at 20°c | > 55 |
| TUBE | Good | Suitable | Suitable | Yes | N/A | > 450 | 550-800 | 20 | 160-240 | > 27 at -20°c | > 45 |
Cromax surfaces
| Corrosion resistance according to ISO 9227 | Technical data | ||||||
|---|---|---|---|---|---|---|---|
| Surface | AASS | NSS | CASS | Surface Roughness | Chrome thickness | Chrome hardness HV01 | |
| Ra (μm) | Rt (μm) | μm | |||||
| Cromax standard | Min 72h R9 | ** | ** | > 0.2 | > 2.0 | > 20 | > 850 |
| Cromax C | Min 120h R9 | ** | - | > 0.2 | > 2.0 | > 20 | > 850 |
| NIKROM 150 | Min. 150 h RIO | Min. 500 h R10 | - | > 0.2 | > 1.6 | Ni > 10 Cr > 20 | > 850 |
| NIKROM 500 | Min. 500 h R 1 0 | Min. 1500 h R10 | - | > 0.2 | > 1.6 | Ni > 30 Cr > 20 | > 850 |
**specified and verified according to agreement
