Heat Treatment Fixtures Material Performance Comparison

In the material selection of vacuum furnace heat treatment fixtures, the core differences between alloys (mainly high-temperature alloys and heat-resistant alloys) and stainless steel (mainly heat-resistant stainless steel) lie in high-temperature stability, creep resistance, service life, and cost. The following is a performance comparison and selection guide to help accurately match heat treatment fixtures requirements:

I. Heat Treatment Fixtures Core Performance Comparison Table

II. Heat Treatment Fixtures Analysis of Key Performance Differences

1. Heat Treatment Fixtures High Temperature Stability: The Core Advantage of Alloys

The high-temperature performance of heat-resistant stainless steel is limited by its matrix structure. When the temperature exceeds 1000℃, grains grow rapidly, leading to a sharp decline in strength and easy deformation or collapse of heat treatment fixtures.
High-temperature alloys form a stable austenitic matrix and strengthening phases by adding elements such as nickel, chromium, molybdenum, and niobium. They can maintain structural stability above 1200℃, making them particularly suitable for heat treatment fixtures used in long-term high-temperature operations such as high-temperature solution treatment, brazing, and sintering.

2. Heat Treatment Fixtures Adaptability to Vacuum Environment

In vacuum furnaces, heat treatment fixtures must withstand low-oxygen, reducing atmospheres and may be subject to carburizing or nitriding processes.

• For stainless steel, chromium on the surface is prone to volatilization at high temperatures in vacuum, forming a chromium-depleted layer that causes intergranular corrosion and heat treatment fixture cracking;
• High-temperature alloys contain high levels of chromium and nickel, which can form a dense, stable oxide film on the surface, effectively preventing element volatilization and corrosion. Meanwhile, their resistance to carburization and nitridation is far superior to that of stainless steel.

3. Heat Treatment Fixtures Thermal Fatigue and Creep Resistance

Heat treatment fixtures must undergo repeated "heating–holding–cooling" cycles, with thermal fatigue and creep being the main failure modes.

• Stainless steel has a relatively large thermal expansion coefficient, and repeated thermal cycles are likely to generate internal stress, leading to cracks. Creep deformation is obvious at high temperatures, making it difficult to maintain the dimensional accuracy of fixtures;
• High-temperature alloys have a lower thermal expansion coefficient and better thermal conductivity, which can effectively disperse thermal stress. Their thermal fatigue and creep resistance can meet the requirements of high-precision, high-frequency heat treatment.

III. Heat Treatment Fixtures Selection Decision Guide

Heat Treatment Fixtures Scenarios for Choosing Heat-Resistant Stainless Steel

1. Heat treatment temperature ≤1000℃ and intermittent operation (e.g., low-temperature tempering, annealing);
2. Simple fixture structure (e.g., baskets, brackets) with low requirements for dimensional accuracy and deformation;
3. Strict cost control and acceptable fixture replacement frequency (replacement every 1–2 years);
4. Neutral or weakly oxidizing working atmosphere without severe processes such as carburization or nitridation.

Recommended Materials: 310S (high cost-performance ratio), 253MA (better high-temperature oxidation resistance than 310S).

Heat treatment fixtures Scenarios for Choosing High-Temperature Alloy

1. Heat treatment temperature ≥1000℃, or long-term high-temperature holding (e.g., high-temperature solution treatment, brazing);
2. Fixtures need to bear high loads (e.g., racks, furnace bottom plates for heavy workpieces) or have extremely high requirements for dimensional accuracy (e.g., positioning fixtures, clamps);
3. Working environment is vacuum or reducing atmosphere, or involves processes such as carburization or nitridation;
4. Pursuit of long service life and low maintenance costs, suitable for mass, continuous production working conditions.

Recommended Materials: Inconel 600 (commonly used for vacuum furnace fixtures with balanced cost-performance ratio), Inconel 625 (high strength and corrosion resistance, suitable for severe working conditions).

IV. Heat Treatment Fixtures Supplementary Suggestions

1. Composite Structure Solution: If cost is sensitive but partial high-temperature performance is required, a "alloy + stainless steel" composite structure can be adopted. For example, key stress-bearing parts of fixtures (high-temperature areas, load-bearing areas) use alloys, while auxiliary structures use stainless steel, balancing performance and cost.

2. Material Verification: For specific working conditions, suppliers can be required to provide high-temperature tensile test reports and oxidation resistance test reports of materials to ensure performance meets requirements.

3. Adaptability for Wuxi Junteng Fanghu Alloy Technology Co., Ltd.: The company's main alloy materials (e.g., heat-resistant alloys, high-temperature alloys) can accurately match the requirements of vacuum furnace fixtures for high temperature, high load, and vacuum atmosphere. Compared with stainless steel, they can significantly improve the service life and production stability of fixtures, especially suitable for the manufacture of fixtures for high-end heat treatment processes.

V. Summary

• Short-term cost priority, low-temperature working conditions: Choose heat-resistant stainless steel;
• Long-term performance priority, high-temperature/severe working conditions: Choose high-temperature alloy.

Although the initial investment in alloy fixtures is higher, the long-term total cost can be reduced through extending service life, reducing downtime for replacement, and ensuring product accuracy, making them more suitable for heat treatment enterprises pursuing efficient and stable production.