321/321H Stainless Steel
321合金（UNS S32100）是一种钛稳定奥氏体不锈钢，具有良好的一般耐腐蚀性。
Type 321 is basic type 304 modified by adding titanium in an amount at least 5 times the carbon plus nitrogen contents.
这些含钛不锈钢具有抗碳化物沉淀的稳定性，设计用于在产生碳化物沉淀的破坏性温度范围内操作。在这种钢中，碳优先与钛结合，形成无害的碳化钛，使溶液中的铬保持完全的耐腐蚀性。
Common Applications
- Aerospace – piston engine manifolds
- Chemical Processing
- Expansion Joints
- Food Processing – equipment and storage
- Petroleum Refining – polythionic acid service
- Waste Treatment – thermal oxidizers
Specifications -321/321H Stainless Steel
- ASTM:A312, A403, A182
- ASME: SA312, SA403, SA182
Chemical Composition - 321/321H Stainless steel
| 等级 |
321 |
321H |
| UNS Designation |
S210000 |
S32109 |
| Carbon (C) Max. |
0.08 |
0.04 – 0.10 |
| Manganese (Mn) Max. |
2.00 |
2.00 |
| Phosphorous (P) Max. |
0.040 |
0.040 |
| Sulphur (S) Max. |
0.030 |
0.030 |
| 硅（Si）最大值。 |
0.75 |
0.75 |
| 铬（Cr） |
17.0 – 20.0 |
17.0 – 20..0 |
| Nickel (Ni) |
9.0 – 12.0 |
9.0 – 12.0 |
| Molybdenum (Mo) |
— |
— |
| Nitrogen (N) |
0.1 Max. |
0.1 Max. |
| Iron (Fe) |
巴尔。 |
巴尔。 |
| 其他要素 |
Ti=5(C) to 0.70% |
Ti=5(C) to 0.60% |
*The titanium content shall not be less than 5 times the carbon content and not more than 0.60%. 321H requires the titanium content to be not less than 4 times the carbon content and not more than 0.60%.
Typical Mechanical Properties
| Material |
Tensile Strength Rm, N/mm² |
Yield Strength Rp 0.2, N/mm²
|
% Elongation |
321合金管
|
500-730 |
200 |
35 |
Design Features - 321/321H Stainless Steel
- Immune to intergranular corrosion when heated within the carbide precipitation range.
- 通过将碳和氮作为碳化钛或氮化物结合起来，添加钛可以消除晶界处碳化铬的形成。
- 比304或304L更好的高温性能。通常用于间歇加热至1500°F的零件。对于连续使用，合金的温度可高达1650°F。
- May be susceptible to chloride stress cracking.
- Excellent weldability in field.
- Type 321H has high carbon (.04 to .10) for better high temperature creep properties.
Typical Applications - 321/321H Stainless Steel
- High temperature chemical process heat exchanger tubes
- Refineries
- High temperature steam service
Tensile Requirements - 321/321H Stainless Steel
- Tensile Strength(KSI):75
- Yield Strength(KSI):30
Proces：
Alloy 321/H can be easily welded and processed by standard shop fabrication practices.
热成形
- Working temperatures of 2100 – 2300°F (1149 – 1260°C) are recommended for forging, upsetting and other hot working processes.
- Alloy not suitable for work at temperatures below 1700°F (927°C).
- Material must be water quenched or fully annealed after working to re-attain maximum corrosion resistance.
Cold Forming
- Quite ductile and forms easily.
Welding
- Readily welded by most standard processes.
- Post weld heat treatment is not necessary
Machining
- Hardening rate of 321 makes it less machinable than 410 stainless steel, but similar to 304
Corrosion Resistance
- exhibits good general corrosion resistance that is comparable to 304.
- developed for use in the chromium carbide precipitation range of 1800 – 1500°F (427 – 816°C) .
- can be used in most diluted organic acids at moderate temperatures .
- can be used in pure phosphoric acid at lower temperatures.
- can be used in up to 10% diluted solutions at elevated temperatures.
- resists polythionic acid stress corrosion cracking in hydrocarbon service.
- utilized in chloride or fluoride free caustic solutions at moderate temperatures.
- 在氯化物溶液中，即使是在小浓度下，或在硫酸环境中，性能也不好。
