Ferritic Stainless Steel Tubes Ferrite Stainless Steel
Austenitic | Martensitic | Ferritic | Duplex | Super Duplex | Superaustenitic | Superferritic | Precipitation Hardening
Ferritic Stainless Steel Tubes, in principle, ferrite at all temperatures. This is achieved by a low content of austenitic forming elements, mainly nickel, and a high content of ferrite forming elements, mainly chromium. Ferritic types, such as 4003 and 4016, are mainly used for household utensils, catering equipment and other purposes where corrosion conditions are not particularly demanding.
Steel with high chromium content, such as 4762 with 24% chromium, are used at high temperature where their resistance to sulphurous flue gages is an advantage. However, the risk of 475 °C embrittlement and precipitation of brittle sigma phase in high-chromium steel must always be taken into consideration. Ferritic stainless steel, such as 4521 with extremely low carbon and nitrogen contents, find greatest use where there is a risk of stress-corrosion cracking.
Ferritic stainless steel have slightly higher yield strength (Rp 0.2) than austenitic steels, but they have less elongation at fracture. Another characteristic that distinguishes ferritic steel from austenitic material is that ferritic steel have much lower strain hardening.
Ferritic grades have been developed to provide a group of stainless steel to resist corrosion and oxidation, while being highly resistant to stress corrosion cracking. These steels are magnetic but cannot be hardened or strengthened by heat treatment. They can be cold worked and softened by annealing. As a group, they are more corrosive resistant than the martensitic grades, but generally inferior to the austenitic grades. Like martensitic grades, these are straight chromium steels with no nickel. They are used for decorative trim, sinks, and automotive applications, particularly exhaust systems.
Mainly Standard include:
ASTM A268 Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service
JIS G3463 Stainless Steel for Boiler and Heat Exchanger Tubes
GB/T 30065 Welded ferritic stainless steel tubes for feedwater heater
GB/T 30066 Welded ferritic stainless steel tubes for heat-exchanger and condenser
| Type 430 | The basic ferritic grade, with a little less corrosion resistance than Type 304. This type combines high resistance to such corrosives as nitric acid, sulfur gases, and many organic and food acids. |
| Type 405 | Has lower chromium and added aluminum to prevent hardening when cooled from high temperatures. Typical applications include heat exchangers. |
| Type 409 | Contains the lowest chromium content of all stainless steels and is also the least expensive. Originally designed for muffler stock and also used for exterior parts in non-critical corrosive environments. |
| Type 434 | Has molybdenum added for improved corrosion resistance. Typical applications include automotive trim and fasteners. |
| Type 436 | Type 436 has columbium added for corrosion and heat resistance. Typical applications include deep-drawn parts. |
| Type 442 | Has increased chromium to improve scaling resistance. Typical applications include furnace and heater parts. |
| Type 446 | Contains even more chromium added to further improve corrosion and scaling resistance at high temperatures. Especially good for oxidation resistance in sulfuric atmospheres. |
Ferritic Stainless Steel / Super Ferritic Stainless Steel Comparison Chart
| GB | ISO Unified Digital Code | ASTM / ASME | UNS Code | EN Code | Company Commercial Grade |
|---|---|---|---|---|---|
| 06Cr13Al | S11348 | 405 | S40500 | 1.4002 | – |
| – | 409 409L | S40900 | 1.4512 | ||
| 0Cr13SiAl | – | – | – | 1.4724 | SIC9(Sanyo)/ 1C256(Sandvik) |
| 10Cr17 | S11710 | 430 | S43000 | 1.4016 | – |
| 022Cr18Ti | S11863 | 439 | S43035 | 1.451 | – |
| 019Cr19Mo2NbTi | S11972 | 444 | S44400 | 1.4521 | – |
| 0Cr18SiAl | – | – | – | 1.4742 | SIC10(Sanyo)/ 1C356(Sandvik) |
| 0Cr24SiAl | – | – | – | 1.4762 | SIC12(Sanyo) |
| 16Cr25N | S12550 | TP446-1/TP446-2 | S44600 | 1.4762 | 2C52/2C48(Sandvik) |
| 1Cr25Ti | – | – | – | – | QS25T(Sanyo) |
| 00Cr27Mo3Ni2TiNb | – | S44660 | S44660 | – | Sea-Cure(Plymouth Tube) |
| 00Cr29Mo4TiNb | – | S44735 | S44735 | – | AL29-4C(ATI) |
| 00Cr29Mo4Ni2TiNb | – | S44736 | S44736 | – | AL29-4-2(ATI) |
| – | S44300 | S44300 | 1.4522 | 443 |
Ferritic Stainless Steel, which are part of the 400 series of stainless alloys, have chromium as their major alloying element and are typically low in carbon content. Ductility and formability are less than that of the austenitic grades. The corrosion resistance is comparable to that of the austenitic grades in certain applications. Thermal conductivity is about half that of carbon steels. Ferritic stainless steel are magnetic, they generally have good ductility and can be welded or fabricated without difficulty. These grades can be processed to develop an aesthetically pleasing, bright finish and, hence, are sometimes used for automotive trim and appliance molding. They also find use in functional applications where cost is a major factor, e.g., automotive exhaust systems, catalytic converters, radiator caps, and chimney liners. These grades can be hardened by cold rolling, but cannot be hardened as much as the austenitic alloys.
Stainless Steel – Ferritic
| lloy (UNS Designation) | End Use | Composition nominal wt% | Specification | Density lb/in3 (g/cm3) | Tensile Strength ksi. (MPa) | 0.2% Yield Strength ksi. (MPa) | Elong- ation % | Hardness |
| AL 18CrCb S44100 | Exhaust system component | C 0.03 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 17.5-19.5, Ni 1.0 max, Ti 0.10-0.50, Cb (0.3+(9/C))min-0.9 max, N 0.03 max, Fe Balance | 0.278 (7.70) | 60min (415 min) | 38 min (260 min) | 25 min | 88 Rockwell B max | |
| ATI 409 HP S40900, S40910 /S40920 /S40930 | Exhaust systems, mufflers, manifolds, exhaust pipes, catalytic converters, tail pipes, thermostats fuel filters, culverts, home heating systems, electrical transformer cases, caskets, heat exchanger tubing, farm equipment, blades, vanes in standby power generation turbines and jet engine sound-deadening devices at airports | C 0.03 max, Mn 1.0 max, P 0.04 max, S 0.02 max, Si 1.0 max, Cr 10.5-11.7, Ni 0.5, N 0.03, Ti 0.05 min, (Ti+Cb) [0.08+8x(C+N)] min-0.75 max, Fe Balance | ASTM A 176 ASTM A240/A240M ASME SA-240/SA-240M ASTM A268 | 0.280 (7.75) | 55 min (380 min) | 25 min (170 min) | 20 min | 88 Rockwell B max |
| AL 409 Cb S41045 | Exhaust components | C 0.03 max, Mn 1.0 max, P 0.045 max, S 0.03 max, Si 1.0 max, Cr 12.0-13.0, Ni 0.5 max, N 0.03 max, Cb 9x(C+N) min-0.60 max. | ASTM A240 ASTM A268 | 0.280 (7.75) | 55 min (380 min) | 30 min (205 min) | 22 min | 80 Rockwell B max |
| AL 410S S41008 | Tower packing, distillation trays, automotive exhaust components, and other high-temperature applications | C 0.08 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 11.5-13.5, Ni 0.6 max, Fe Balance | ASTM A240 ASTM A268 ASTM A176 | 0.280 (7.75) | 60 min (415 min) | 30 min (205 min) | 22 min | 89 Rockwell B max |
| AL 412 S41003 | Rail cars, coal handling equipment, sugar processing equipment, mining equipment, storage bins and hoppers, bus frames | C 0.03 max, Mn 1.5 max, Si 1.0 max, P 0.04 max, S 0.03 max, Cr 10.5-12.5, Ni 1.5 max, Fe Balance | ASTM A240 ASTM A268 | 0.280 (7.75) | 66 min (455 min) | 40 min (275 min) | 18 min | 20 Rockwell C max |
| 430 S43000 | Interior and exterior trim applications such as sinks, sink rims, appliance trim, counter tops, dish washers, range hoods, flatware, roofing, siding and restaurant equipment | C 0.12 max, Mn 1.0 max, Si 1.0 max, Cr 16.0-18.0, Ni 0.75 max, Fe Balance | ASTM A240 ASTM A268 | 0.278 (7.70) | 65 min (450 min) | 30 min (205 min) | 22 min | 89 Rockwell B max |
| AL 430 Ti S43036 | Welded tubing | C 0.10 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 16-19.5, Ni 0.75 max, Ti (5xC) min-0.75 max, Fe balance | ASTM A268 A554 | 0.280 (7.75) | 60 min (415 min) | 35 min (240 min) | 20 min | 90 Rockwell B max |
| AL 433 | Exhaust components | C 0.01, Mn 0.3, P 0.02, S 0.001, Si 0.4, Cr 20.0, Ni 0.25, Cu 0.5, N 0.02, Cb 0.54 (0.8 max) Cb/(C+N)>10, Fe Balance | 0.280 (7.75) | 63.4 (440) | 46.7 (322) | 31 | 79 Rockwell B | |
| AL 436S | Exhaust systems | C 0.01, Mn 0.2, P 0.02, S 0.001, Si 0.37, Cr 17.3, Ni 0.3, Mo 1.2, N 0.015, Ti/(C+N)>8 | 0.280 (7.75) | 66 (455) | 43 (296) | 30.5 | 77 Rockwell B | |
| 439/ATI 439 HP S43035 | Automotive exhaust, manifolds and mufflers; residential funace primary heat exchangers; direct-fired hot water tanks; heat exchanger tubing | C 0.03 max, Mn 1.0 max, Si 1.0 max, Cr 17.0-19.0, Ni 0.5 max, N 0.03 max, Al 0.15 max, Ti [0.2+4(C+N)] min-1.10 max | Pipe & Tubing: ASTM A268 ASME SA268 ASTM A803 Flat Rolled Products: ASTM A240 ASME SA240 Bar Products: ASTM A479 ASME SA479 | 0.278 (7.70) | 60 min (415 min) | 30 min (205 min) | 22 min | 89 Rockwell B max |
| AL 441HP S44100 | Exhaust Components | C 0.03 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 17.5-19.5, Ni 1.0 max, Ti 0.1-0.5, Cb 0.3+(9xC) min-0.9 max, Fe Balance | 0.278 (7.70) | 72 (495) | 45 (310) | 31 | 82 Rockwell B | |
| AL 444 S44400 | Heat exchanger tubing, food processing equipment, hot water tanks, automotive exhaust | C 0.025 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 17.5-19.5, Ni 1.0 max, Mo 1.75-2.5, N 0.035 max, (Ti+Cb) [0.2+4(C+N)] min-0.8 max, Fe Balance | ASTM A240, A 268, A276 ASME SA 240, SA 268 | 0.280 (7.75) | 60 min (415 min) | 40 min (275 min) | 20 min | 96 Rockwell B max |
| AL 453 | Elevated temperature applications such as planar solid oxide fuel cells | C 0.03, Mn 0.3, P 0.02, S 0.03 max, Si 0.3, Cr 22.0, Ni 0.3, Al 0.6, Ti 0.02, (Ce+La) 0.1 max, Fe Balance | 0.275 (7.61) | 68 (470) | 45 (310) | 35 | 78 Rockwell B | |
| AL 468 S46800 | Automotive exhaust, residential furnace primary heat exchanger | C 0.03 max, Mn 1.0 max, P 0.04 max, S 0.03 max, Si 1.0 max, Cr 18.0-20.0, Ni 0.5 max, N 0.03 max, Ti 0.07-0.3, Cb 0.10-0.60, (Ti+Cb) [0.2+4(C+N)] min-0.8 max | ASTM A240 | 0,278 (7.70) | 60 min (415 min) | 30 min (205 min) | 22 min | 90 Rockwell B max |
| OHMALOY 30 K91470 | Grid resistors for mine locomotives, Crane starters, Braking resistors for railroad diesel locomotives | C 0.025, Mn 0.35, Si 0.3, Cr 13.0, Al 3.0, Ti 0.3, Fe Balance | 0.270 (7.48) | 76 (524) | 55 (379) | 28 | 88 Rockwell B | |
| OHMALOY 40 K91470 | Grid resistors for mine locomotives, Crane starters and Braking resistors for railroad diesel locomotives | C 0.025, Mn 0.35, Si 0.3, Cr 13.0, Al 3.95, Ti 0.3, Fe Balance | 0.267 (7.39) | 87 (600) | 65 (448) | 23 | 88 Rockwell B |
Metallographic Test – Metallography Testing
Metallographic Test Report
Related References:
1. Superferritic Stainless Steel
2. Ferritic Ferrite Stainless Steel
3. Ferritic Stainless Steel Grades Comparison Table
4. Compared with the ferritic stainless steel, duplex stainless steel vulnerable
5. 405 S11348 X6CrAl13 Chemical Composition