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ASTM A213 TP321 TP304 Bright Annealed Stainless Steel Seamless Tube For Heat Exchangers
YUHONG GROUP has been engaged in seamless welded pipes and pipes of austenitic stainless steel and nickel alloy steel (Hastelloy, Monel, Inconel, Inconel) for more than 30 years, with annual sales of more than 100,000 tons of steel pipes and pipes. pipeline. Our customers are located in over 55 countries.
Stainless Steel 321 is a basic austenitic 18/8 steel (grade 304) stabilized by the addition of titanium (321). SS 321 are used because they are not susceptible to intergranular corrosion after heating in the carbide precipitation range of 425-850°C. SS 321 is the grade of choice for applications in the temperature range up to about 900°C, combining high strength, resistance to scaling and phase stability with subsequent resistance to water corrosion. SS 321H is an improved version of SS 321 with a higher carbon content to provide higher high temperature strength.
Specifications:
Stainless Steel SS 321 / 321H | |
---|---|
AISI | 321 / 321H |
UNS | S32100 / S32109 |
Werkstoff Nr. | 1.4541 / 1.4878 |
Mechanical & Physical Properties:
Density | 8.0 g/cm3 |
Melting Point | 1454 °C (2650 °F) |
Tensile Strength | Psi – 75000 , MPa – 515 |
Yield Strength (0.2%Offset) | Psi – 30000 , MPa – 205 |
Elongation | 35 % |
Chemical Composition
SS 321 | SS 321H | |
Ni | 9 – 12 | 9 – 12 |
Cr | 17 – 19 | 17 – 19 |
C | 0.08 max | 0.04 – 0.10 |
N | 0.10 max | |
Fe | Balance | |
Mn | 2 max | 2 max |
Si | 0.75 max | 0.75 max |
S | 0.03 max | 0.03 max |
P | 0.045 max | 0.045 max |
Ti | 5xC min 0.60% max | 4xC min 0.60% max |
Alloys 321 (S32100) and 347 (S34700) are stable stainless steels
whose main advantage is their excellent resistance to intergranular
corrosion after exposure to the chromium carbide precipitation
temperature range of 800 to 15000F (427 to 8160C). Alloy 321
stabilizes chromium carbide formation by adding titanium. Alloy 347
is stabilized by the addition of niobium and tantalum.
While Alloys 321 and 347 continue to be used for long-term use in
the 800 to 15000F (427 to 8160C) temperature range, Alloy 304L has
superseded these stable grades for applications involving only
welding or short-term heating.
Alloy 321 and 347 stainless steels are also beneficial for high
temperature applications because of their good mechanical
properties. Alloy 321 and 347 stainless steels offer higher creep
and stress rupture properties than Alloy 304, especially Alloy
304L, which can also be considered for exposures concerned with
sensitization and intergranular corrosion. This results in higher
high temperature allowable stresses for these stable alloys used in
ASME boiler and pressure vessel code applications. Alloys 321 and
347 have a maximum service temperature of 15000F (8160C) for code
applications such as Alloy 304, while Alloy 304L is limited to
8000F (4260C).
High carbon versions of both alloys are available. These grades
have UNS designations S32109 and S34709.
Resistance to Corrosion:
General Corrosion:
Alloys 321 and 347 offer general bulk corrosion resistance similar
to the unstable chromium-nickel alloy 304. Prolonged heating in the
chromiumcarbide precipitation range may affect the general
resistance of alloys 321 and 347 in severely corrosive media.
In most environments, both alloys will exhibit similar corrosion
resistance; however, Alloy 321 in the annealed condition is
slightly less resistant to general corrosion than annealed Alloy
347 in a strongly oxidizing environment. Therefore, Alloy 347 is
more suitable for water and other low temperature environments. The
overall corrosion resistance of Alloy 321 is much more degraded
than Alloy 347 when exposed to the temperature range of 8000F to
15000F (4270C to 8160C). Alloy 347 is primarily used in high
temperature applications where high resistance to sensitization is
required to prevent intergranular low temperature corrosion.
Physical Properties:
The physical characteristics of the Models 321 and 347 are very
similar and, for all practical purposes, can be considered the
same. The values given in the table can be used for both steels.
When properly annealed, Alloy 321 and 347 stainless steels consist
primarily of austenite and carbides of titanium or niobium. Small
amounts of ferrite may or may not be present in the microstructure.
A small amount of sigma phase may form during prolonged exposure in
the temperature range of 10000F to 15000F (5930C to 8160C).
Stable Alloy 321 and 347 stainless steels cannot be hardened by
heat treatment.
The overall heat transfer coefficient of a metal depends on factors
other than the thermal conductivity of the metal. In most cases,
film coefficients, fouling, and surface conditions make stainless
steels that require no more than 10% to 15% surface area than other
metals with higher thermal conductivity. Stainless steel's ability
to maintain a clean surface generally has better heat transfer than
other metals with higher thermal conductivity.