Ferritic SS 446 Pipes and tubes
The grade 446 stainless steel is a ferritic, non-heat treatable stainless steel that provides good
resistance to high temperature oxidation and corrosion.
Chemical properties for SS 446
| GRADE | Cu | Ni | Mn | Si | Ni | C | P | S | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|
| SS 446 | Min | 23 | 29 | – | – | – | – | BALANCE | ||
| Max | 27 | 33 | 1.5 | 1 | 0.25 | 0.2 | 0.04 | 0.03 |
Specification
Stainless steel 446 Seamless Pipe : ASTM/ASME SA 790/ A 790
Stainless steel 446 Seamless tube : ASTM/ASME SA 268 /A 268
Stainless steel 446ERW Pipe : ASTM/ASME SA 790/ A 790
Stainless steel 446ERW Tube : ASTM/ASME SA 268/ A 268
Specifications
| GRADE | UNS | EN | JIS |
|---|---|---|---|
| SS 446 | S46600 | 1.4762 | SUS 446 |
Production Process
Grade SS 446 Pipe or UNS S44600 are manufactured through processes such as ERW (Electric
Resistance Welded), Seamless and EFW (Electric Fusion Welding). 446 stainless steel pipe and
446 stainless steel Tube have different forms such as round, square, rectangle etc. having
specific end as Plain End, Bevel End and Threaded End with nominal thickness of different
schedule ranging from SCH 5 to SCH XXS.
The process through which stainless steel 446 pipes and stainless steel 446 tube can be
manufactured include cold pilgering process, Extrusion process, tube mill Process also Piercing
process followed by heat treatment and mechanical testing.
Fabrication and Heat Treatment
The hot working of grade 446 stainless steel is performed in between the ranges 1093- 1177°C
(2000-2150° F). The grade 446 stainless steel is more difficult to cold work than other stainless
steels due to the high level of chromium content.
For annealing of the grade 446 stainless steel, it has to be soaked at 816°C (1500°F) and then
water quenched. The temperature should not exceed 900°C (1650°F) at any time and slow
cooling below 649°C (1200°F) can cause loss of ductility.
The grade 446 stainless steel can be easily welded using most of the traditional methods except
oxyacetylene welding. Type 308 welding material can be used if required, but it will not exhibit
scaling resistance equal to the base metal.
Properties
SS 446 is a non hardenable chromium steel and exhibits good resistance to reducing sulfurous
gases and fuel-ash corrosion. The rupture and creep characteristics of type 446 stainless are
also good enough but vary at higher temperatures.
Mechanical Properties
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness,MAX | |
|---|---|---|---|---|---|
| [MPA] | [MPA] | (% in 50mm) min | HBW | HRB | |
| SS 446 | 485 | 275 | 18 | 95 | 207 |
SS 446 ERW Pipes does not require annealing after welding to restore ductility or to provide
inter-granular corrosion resistance. Stainless Steel 446 Seamless Pipes are iron alloys, which
have 89 % of their average alloy composition in common.
Physical Properties
| Grade | Density (g/cm3) | Elastic Modulus (GPa) | Coeff of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) |
|---|---|---|---|---|
| 0-100°C | ||||
| SS 446 | 7.8 | 200 | 10.4 | 21.6 |
SS 446 are tougher than other stainless steels to draw, bend, spin and weld because of its
elevated chromium content. Soaking at 1500 F and water quench. Try not to surpass 1650 F at
any time. Slow cooling below 1200 F will result in the loss of ductility.
Application
SS 446 Tube and Pipes are used for vast spread application in multiple industries like Sugar,
Nuclear, Marine, Defense, Fabrication etc. and also supplied in niche market like Oil & Gas,
Dairy, Chemical & Fertilizer, Thermal, Refinery & Petrochemicals, LNG, Desalination, Solar &
Nuclear Power, Automobiles etc. Various 446 stainless steel pipe manufacturers produce SS
446 equipment that can be used in multiple industries.
