What are the advantages and disadvantages of each?

The material selection of the heat treatment tray/frame directly affects its high temperature resistance, service life, cost and applicable scenarios. Common materials and their respective advantages and disadvantages are as follows:

一. Metal material
1. Heat-resistant steel (most commonly used)
Types: Cr25Ni20 (310S), Cr18Ni9 (304), Cr20Ni14Si2, etc.
Advantages:
Excellent high temperature resistance, can withstand 600-1200℃ (310S can reach above 1200℃);
High mechanical strength, strong impact and deformation resistance, suitable for loading heavy workpieces;
Weldable, good processability, easy to make into complex shapes (such as holes, grid structures);
Good oxidation and corrosion resistance, suitable for various heat treatment atmospheres such as air and nitrogen.
Disadvantages:
High cost (especially high nickel-chromium models);
Creep (slow deformation) may occur under long-term high temperature, requiring regular inspection;
Heavy weight, may increase equipment energy consumption.

2. Cast iron (gray cast iron, ductile iron)
Advantages:
Low cost, suitable for low temperature heat treatment scenarios (such as 200-600℃);
Good casting performance, can mass produce simple-shaped trays/frames.
Disadvantages:
Poor high temperature resistance, easy to oxidize and crack above 600℃;
High brittleness, weak impact resistance, easy to be damaged by workpiece collision or sudden temperature change.

二. Ceramic materials
1. Alumina ceramics (Al₂O₃)
Advantages:
High temperature resistance, can withstand temperatures above 1600℃, suitable for high temperature sintering, brazing and other scenarios;
Good chemical stability, acid and alkali corrosion resistance, no chemical reaction with the workpiece;
Lighter than metal, can reduce equipment load;
Smooth surface, workpieces are not easy to stick.
Disadvantages:
High brittleness, poor impact and vibration resistance, easy to break due to collision or sudden temperature change;
High processing difficulty, high cost of making complex shapes;
Low mechanical strength, not suitable for loading heavy workpieces.

2. Silicon carbide ceramics (SiC)
Advantages:
High temperature resistance (1600-1800℃) and good thermal conductivity, can evenly transfer heat;
Thermal shock resistance is better than alumina ceramics, and can withstand large temperature changes;
High hardness and good wear resistance, suitable for scenes with friction or wear.
Disadvantages:
Extremely high cost, far exceeding metal and alumina ceramics;
The brittleness is still obvious, and caution is required when loading and unloading workpieces.

三. Other materials
1. Heat-resistant alloys (such as Inconel, Hastelloy)
Advantages:
High temperature resistance (1000-1200℃) and excellent creep resistance, suitable for long-term high temperature use;
Extremely strong corrosion resistance, can be used in harsh heat treatment atmospheres such as sulfur and chlorine (such as carburizing and nitriding).
Disadvantages:
Extremely high cost, only used for high-end precision heat treatment (such as aerospace parts);
Difficult processing, welding requires special processes.

2. Graphite
Advantages:
High temperature resistance (above 2000℃), suitable for high temperature heat treatment in vacuum or inert gas;
Good thermal conductivity, low thermal expansion coefficient, excellent thermal shock resistance.
Disadvantages:
Easy to oxidize (protective atmosphere is required above 500℃ in air);
Low strength, high brittleness, easy to wear, and short service life.

Summary:
Low-cost, medium-low temperature scenarios: cast iron or ordinary heat-resistant steel (such as 304) is preferred;
High-temperature, high-load scenarios: high-nickel-chromium heat-resistant steel (such as 310S);
Ultra-high temperature, corrosion-resistant or clean environment: ceramic (aluminum oxide, silicon carbide) or graphite (needs to be matched with a protective atmosphere);
High-end precision requirements: heat-resistant alloys (when costs allow).

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