What are the surface treatment methods for crane pins?

The core objectives of surface treatment for crane pins are: rust prevention, wear resistance, friction reduction, extended service life, and anti-galling.

Common Surface Treatments for Crane Pins

1. High-Frequency Induction Hardening (Most Common, Essential for Heavy Loads)

Treatment Area: Working friction surface of the pin

Features:

High surface hardness and wear resistance, core retains toughness

No deformation, high precision

Hardness: HRC 45～55

Application: All articulated main pins of truck cranes, crawler cranes, gantry cranes, and bridge cranes

2. Blackening (Bluing)

Function: Rust prevention, aesthetics

Features: Low cost, thin film, not wear-resistant

Application: Non-friction parts, installation mating sections

3. Galvanizing / Galvanized Passivation

Function: Rust prevention

Features: Good corrosion resistance, but the coating is relatively soft and not wear-resistant

Caution: Strictly prohibited on friction mating surfaces, as it will wear off and damage the pin sleeve.

4. QPQ Salt Bath Composite Treatment (High-end, Wear-resistant + Corrosion-resistant)

Features:

High surface hardness (HV) 600-800)

Extremely wear-resistant, extremely rust-resistant, with minimal deformation

Suitable for:

High-end cranes, port cranes, high-altitude operations, corrosive environments (coastal areas)

5. Spraying/Welding Wear-Resistant Alloys (Extra-heavy-duty, Harsh Working Conditions)

Etc.: Tungsten Carbide, Nickel-Based Alloys

Suitable for:

High wear, high impact, mining cranes, crawler crane main pin shafts

6. Hard Chrome Plating (Traditional Wear-Resistant Treatment)

High hardness, wear-resistant, rust-resistant

Disadvantages: Plating is prone to peeling and flaking, environmentally restricted

Use is gradually decreasing in large cranes

Simplest Summary (Direct Selection on-site)

Friction Working Section: High-frequency quenching (standard) or QPQ (high-end)

Non-friction Rust Prevention: Blackening, Zinc Plating

Strictly Prohibited: Zinc plating on friction surfaces, ordinary spray painting