321 stainless steel pipe

321 stainless steel pipe



Product Description

321 Stainless Steel Pipe

321 Stainless Steel Pipe

Grades 321 and 347 are the basic austenitic 18/8 steel (Grade 304) stabilised by Titanium (321) or Niobium (347) additions. These grades are used because they are not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C.

 

321 stainless steel pipe is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.Grade 321H is a modification of 321 with a higher carbon content, to provide improved high temperature strength.A limitation with 321 is that titanium does not transfer well across a high temperature arc, so is not recommended as a welding consumable. In this case grade 347 is preferred – the niobium performs the same carbide stabilisation task but can be transferred across a welding arc. Grade 347 is therefore the standard consumable for welding 321.

 

 

Grade 347 is only occasionally used as parent plate material.Like other austenitic grades, 321 and 347 have excellent forming and welding characteristics, are readily brake or roll formed and have outstanding welding characteristics.

Applications of 321 stainless steel pipe:

Typical compositional ranges for grade 321 stainless steel pipe are given in table 1.

Table 1. Composition ranges for 321 grade stainless steel

Grade

C

Mn

Si

P

S

Cr

Mo

Ni

N

Other

321

min.

max

-

0.08

2.00

0.75

0.045

0.030

17.0

19.0

-

9.0

12.0

0.10

Ti=5(C+N)

0.70

321H

min.

max

0.04

0.10

2.00

0.75

0.045

0.030

17.0

19.0

-

9.0

12.0

-

Ti=4(C+N)

0.70

347

min.

max

0.08

2.00

0.75

0.045

0.030

17.0

19.0

-

9.0

13.0

-

Nb=10(C+N)

1.0

Typical mechanical properties for grade 321 stainless steel pipe are given in table 2.

Table 2. Mechanical properties of 321 grade stainless steel

Grade

Tensile Strength (MPa) min

Yield Strength 0.2% Proof (MPa) min

Elongation (% in 50mm) min

Hardness

Rockwell B (HR B) max

Brinell (HB) max

321

515

205

40

95

217

321H

515

205

40

95

217

347

515

205

40

92

201