HOT LINE: +86-510-806281001. Quenching and tempering treatment
The purpose of quenching and tempering treatment is to make the piston rod have comprehensive mechanical properties with good matching of strength, hardness, plasticity and toughness, which is ready for subsequent surface quenching.
2. Surface hardening
The piston rod moves frequently during the working process. Therefore, in addition to having good comprehensive mechanical properties to prevent deformation and fracture, the surface is also required to have high wear resistance. The surface hardness is required to reach 58-62HRC.In the production process, high-frequency quenching is often used.
3. stress relief annealing
Because surface quenching uses the product's own waste heat for tempering treatment, the tempering temperature is gradually reduced, there is no complete tempering heat preservation process. The tempering time is short, the stress relief is incomplete, and there are large residual stresses in some products. Therefore, the piston rod must be annealed before chrome plating to eliminate internal stress caused by grinding and surface treatment.
4. Electroless nickel-phosphorus plating on the surface
In addition to hard chromium plating on the surface of the piston rod for hydraulic cylinders, the outer surface of the piston rod can also be electrolessly plated with nickel and phosphorus;
The surface of the piston rod with special requirements can also be thermal sprayed alloy or sprayed ceramic layer.
Performance comparison of various coatings on piston rods
Type of coating | Coating hardness HV | Wear resistance state | Salt spray test (hours) | Material utilization | Equipment complexity |
Single layer chromium | 700-1000 | Wearable | 48-96 | 20-30 | generally |
Milky white chromium + chromium | 700-1000 | Wearable | 96 | 18-25 | More equipment |
Three layers of chromium | 700-1000 | Wearable | 96-192 | 18-25 | More equipment |
Single layer nickel + chromium | 700-1000 | Abrasion resistance, good binding force | 96-128 | 25-35 | More equipment |
Double nickel + chromium | 700-1000 | Abrasion resistance, good binding force | 96-192 | 20-30 | Complex process |
Electroless Nickel | 500-700 | More wear-resistant | 48-96 | 40-60 | Simple equipment |
Electroless nickel + chromium | 700-1000 | Wearable | 96-192 | 30-50 | generally |
Tungsten alloy Coating | 500-650 | Wearable | 48 | 65 | Complex equipment |
Nickel-iron-cobalt coating | 550-700 | Wearable | 96 | 70 | generally |
Nickel-cobalt-iron Coating (Nano) | 650-750 | Super wear-resistant | Greater than 192 | 85 | generally |
Cobalt Phosphorus Coating | 550-700 | Wearable | Greater than 192 | 80 | generally |
Thermal spray ceramics | 1000-1300 | Wearable | Greater than 192 | 90 | Complex equipment |
Nano chromium coating | 900-1300 | Super wear-resistant | Greater than 500 | 30-50 | Pulse power |
Dw-032 high efficiency chrome plating | 900-1300 | Super wear-resistant | Greater than 750 | 70 | Ordinary equipment |
Structured chrome plating | 800-1000 | Wearable | Greater than 300 | 25-40 | Complex equipment |
