- Description
Stainless steel grades 446 and 405 are ferritic stainless steels with specific characteristics suitable for high-temperature and moderate corrosion environments.
1. 446 Stainless Steel
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Material Type: Ferritic stainless steel
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High Temperature Performance: Can withstand impact temperatures up to 1090°C
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Typical Applications: Steam boiler furnace parts, oil burners, heat exchangers, kiln linings, glass molds, and fixed soot blowers
Forging & Heat Treatment
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Forging: Preheat uniformly to 815–870°C, then raise to forging temperature range ~1120°C. Perform forging below 900°C. Air cooling and annealing are recommended for forged parts.
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Annealing: Conduct annealing at 760–830°C, followed by cooling. Avoid soaking or slow cooling between 370–525°C to prevent embrittlement.
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Heat Treatment: Cannot be hardened by standard heat treatment.
Machining & Welding
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Machining: Can be machined similarly to 442 stainless steel; carbide tools are preferred.
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Welding: Standard fusion and resistance welding methods are suitable. Preheat and postheat between 150–315°C. Use austenitic filler metals such as 310 or 312 stainless steel to maximize weld ductility.
2. 405 Stainless Steel
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Material Type: Ferritic stainless steel
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Corrosion Resistance: Slightly lower than 430 ferritic stainless steel, comparable to 410 stainless steel, but with better weldability
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Typical Applications: Similar to low-chromium ferritic steels; suitable for mildly corrosive environments
Forging & Heat Treatment
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Forging: Can be forged in the range 815–1120°C and air-cooled. Aluminum is added to prevent hardening during high-temperature cooling.
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Annealing: Heat parts to 780°C, soak, then air-cool. Cannot be hardened by heat treatment.
Machining & Welding
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Machining: Comparable to other ferritic stainless steels; better mechanical machinability than austenitic stainless steels
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Welding: All normal fusion and resistance methods are suitable. Aluminum addition improves weldability by preventing hardening during weld cooling
Summary Table – 446 vs 405 Stainless Steel Properties
| Feature | 446 Stainless Steel | 405 Stainless Steel |
|---|---|---|
| Stainless Steel Type | Ferritic | Ferritic |
| Maximum Service Temp | 1090°C | Moderate temperature |
| Corrosion Resistance | Good | Moderate, similar to 410 |
| Typical Applications | Boilers, burners, heat exchangers, kilns, glass molds | Mildly corrosive environments |
| Forging Temperature | 815–870°C preheat, 1120°C forging | 815–1120°C |
| Annealing Temperature | 760–830°C | 780°C |
| Heat Treatable | No | No |
| Machinability | Moderate (use carbide tools) | Better than austenitic steels |
| Weldability | Fusion & resistance welding; pre/postheat 150–315°C | Fusion & resistance welding; improved by aluminum |
