Introduction to the production process of marine anchor chains-Part 2

IV. Heat Treatment Process

1. Quenching and Tempering

- Anchor chains need to undergo 900℃ quenching and 600℃ tempering to enhance strength and toughness.

- Research indicates that the wear resistance is the best when quenched at 860℃, while increasing the tempering temperature will reduce the content of needle-like α-ferrite phase and change the cementite from sheet-like to granular.

2. Optimization of heat treatment parameters

- The holding time during tempering has a significant impact on performance. It has a noticeable effect when the holding time is less than 30 minutes, but the effect becomes smaller when it exceeds 30 minutes.

- The heat treatment equipment must meet requirements such as good heat preservation performance, good uniformity of the furnace temperature, and the provision of a multi-point temperature measurement system.

V. Quality Inspection and Verification

1. Tensile Test

- The complete anchor chain section (referred to as "shots") is approximately 27 meters long and undergoes a tensile test that requires withstanding tens of thousands of tons of force.

- An automatic tensile machine stretches all the links to verify if the strength meets the standards. Any breakage at any stage will cause the entire anchor chain to fail.

2. Non-destructive Testing

- Magnetic particle testing and X-ray flaw detection are used to detect micro-cracks that are invisible to the naked eye.

- Ultrasonic testing examines internal defects to ensure the integrity of the anchor chain structure.

3. Other Tests

- Corrosion Resistance Test: Place the anchor chain in seawater for 7 days and observe the degree of surface rusting.

- Carbon Powder Test: Detect tiny cracks that are not visible to the naked eye.