Description
ASTM A268 TP405; TP410; TP430; TP439; TP444 Ferritic Stainless Steel Pipe For General Service
Material
ASTM A268 specifies ferritic stainless steel pipe produced primarily for general service applications. These pipes are made from different grades of ferritic stainless steel, including TP405, TP410, TP430, TP439, and TP444. Ferritic stainless steels are known for their excellent corrosion resistance, good formability, and magnetic properties, making them suitable for a wide range of industrial uses.
Specification
ASTM A268 covers seamless and welded ferritic stainless steel pipe intended for general use, with strict guidelines for chemical composition, mechanical properties, and manufacturing processes. The specification ensures the pipe material offers consistent quality and performance across applications.
Key Features
- Excellent corrosion resistance in mildly corrosive environments
- Good resistance to stress corrosion cracking
- Magnetic and non-hardenable by heat treatment
- Good mechanical properties and toughness
- Good weldability and formability
- Typically produced in a ferritic microstructure with chromium content varying by grade
Chemical Composition
| Grade | C (max) | Si (max) | Mn (max) | P (max) | S (max) | Cr (min) | Ni (max) | Mo (max) | N (max) | Other Elements |
|---|---|---|---|---|---|---|---|---|---|---|
| TP405 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 11.50-13.50 | 0.50 | 0 | 0.10 | Ti for stabilization |
| TP410 | 0.15 | 1.00 | 1.00 | 0.040 | 0.030 | 11.50-13.50 | 0.75 | 0 | 0.10 | – |
| TP430 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.00-18.00 | 0.75 | 0 | 0.10 | – |
| TP439 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.00-18.00 | 0.75 | 0.75 | 0.10 | Nb stabilized |
| TP444 | 0.020 | 1.00 | 1.00 | 0.040 | 0.030 | 17.00-19.00 | 0.75 | 1.75-2.50 | 0.10 | Nb stabilized |
Note: Values are weight percentages.
Mechanical Properties
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HRB) |
|---|---|---|---|---|
| TP405 | 485 – 620 | 275 (min) | 20 (min) | 80 – 95 |
| TP410 | 550 – 700 | 275 (min) | 18 (min) | 90 – 97 |
| TP430 | 450 – 620 | 205 (min) | 20 (min) | 75 – 95 |
| TP439 | 450 – 620 | 205 (min) | 20 (min) | 75 – 95 |
| TP444 | 485 – 620 | 275 (min) | 20 (min) | 80 – 95 |
Steel Grade
The grades TP405, TP410, TP430, TP439, and TP444 represent a range of ferritic stainless steels differentiated primarily by their chromium, molybdenum, and other alloying element contents. Each grade suits different operational environments, offering variations in corrosion resistance, strength, and thermal stability.
Application
ASTM A268 ferritic stainless steel pipe are commonly used in:
- Automotive exhaust systems (particularly TP409, close to TP405)
- Heat exchangers and boilers
- Kitchen equipment and appliances
- Architectural applications requiring moderate corrosion resistance
- Chemical and petrochemical processing equipment
- Water treatment plants
The specific grade selected depends on the required corrosion resistance, temperature tolerance, and mechanical strength.
Equivalent Grades
| ASTM A268 Grade | UNS Number | EN Standard Equivalent | JIS Standard Equivalent | Other Equivalents |
|---|---|---|---|---|
| TP405 | S40500 | X2CrTi12 (1.4003) | SUS 405 | AISI 405 |
| TP410 | S41000 | X6Cr13 (1.4006) | SUS 410 | AISI 410 |
| TP430 | S43000 | X6Cr17 (1.4016) | SUS 430 | AISI 430 |
| TP439 | S43932 | X2CrNb18 (1.4512) | SUS 439 | AISI 439 |
| TP444 | S44400 | X2CrMoTi18-2 (1.4521) | SUS 444 | AISI 444 |
