ASTM A268 Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing Introduction ASTM A268 specification covers a number of grades of nominal-wall-thickness, welded ferritic and martensitic stainless steel tubing for general corrosion-resisting and high-temperature service like heaters, burners, Petroleum Refining and Petrochemical Processing, Heat exchangers, Thermal Processing, Biomedical, food processing equipment, automotive exhausts, and hot water tanks and more. Specification Standard: ASTM A268/A268M-2022 Grade: TP405, TP410, TP429, TP430, TP443, TP446-1, TP446-2, TP409 Grade: TP439, S41500, S44400, S44700, S44635, TP468 Outside Diameter: 12.7 - 203.2mm Wall Thickness: 0.4 - 8.0mm Length: 3000 - 36000mm Type: Straight Tube, U-Tube TP405, TP410, TP429, TP430, TP443, TP446-1, TP446-2, TP409 Chemical Composition (wt%):
Grade
TP405
TP410
TP429
TP430
TP443
TP446–1
TP446–2
. . .
TP409
UNS No.
S40500
S41000
S42900
S43000
S44300
S44600
S44600
S40800
S40900
Element
Composition, %
C, max
0.08
0.15
0.12
0.12
0.2
0.2
0.12
0.08
0.08
Mn, max
1
1
1
1
1
1.5
1.5
1
1
P, max
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.045
0.045
S, max
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.045
0.03
Si, max
1
1
1
1
1
1
1
1
1
Ni
0.50 max
. . .
. . .
. . .
0.75 max
0.75 max
0.50 max
0.80 max
0.50 max
Cr
11.5–14.5
11.5–13.5
14.0–16.0
16.0–18.0
18.0–23.0
23.0–27.0
23.0–27.0
11.5–13.0
10.5–11.7
Al
0.10–0.30
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
Cu
. . .
. . .
. . .
. . .
0.90–1.25
. . .
. . .
. . .
. . .
N
...
...
...
...
...
0.25
0.25
...
...
Ti
...
...
...
...
...
...
...
12 x C min; 1.10 max
6 x C min; 0.75 max
TP439, S41500, S44400, S44700, S44635, TP468 Chemical Composition (wt%):
Grade
TP439
. . .
TPXM-27
18Cr-2Mo
29-4
29-4-2
26-3-3
25-4-4
TP468
UNS
S43035
S41500
S44627
S44400
S44700
S44800
S44660
S44635
S46800
Element
Composition, %
C, max
0.07
0.05
0.01
0.025
0.01
0.01
0.03
0.025
0.03
Mn,max
1
0.5–1.0
0.4
1
0.3
0.3
1
1
1
P, max
0.04
0.03
0.02
0.04
0.025
0.025
0.04
0.04
0.04
S, max
0.03
0.03
0.02
0.03
0.02
0.02
0.03
0.03
0.03
Si, max
1
0.6
0.4
1
0.2
0.2
1
0.75
1
Ni
0.50 max
3.5–5.5
0.5max
1.00 max
0.15 max
2.0–2.5
1.0–3.50
3.5–4.5
0.5
Cr
17.00–19.00
11.5–14.0
25.0–27.5
17.5–19.5
28.0–30.0
28.0–30.0
25.0–28.0
24.5–26.0
18.00–20.00
Mo
...
0.5–1.0
0.75–1.50
1.75–2.50
3.5–4.2
3.5–4.2
3.0–4.0
3.5–4.5
. . .
Al, max
0.15
. . .
...
...
...
...
...
...
. . .
Cu,max
...
. . .
0.2
...
0.15
0.15
...
...
. . .
N, max
0.04
. . .
0.015
0.035
0.020
0.020
0.04
0.035
0.03
Ti
0.20 + 4(C+ N) min; 1.1 max
...
...
(Ti + Cb) 0.20 + 4 (C + N) min; 0.8 max
...
...
(Ti + Cb)=0.20–1.00 and 6 x (C + N) min
(Ti + Cb) = 0.20 + 4 (C + N) min 0.8 max
0.07–0.30
Cb
...
. . .
0.05–0.20
...
...
...
...
...
0.10–0.60 (Ti + Cb)=0.2+4(C+N) min; 0.8 max
ASTM A268/A268M Stainless Steel Tubing Mechanical Properties: ASTM A268/A268M Stainless Steel Tubing Hardness requirements: Manufacture The tubes shall be made by the seamless or welded process with no filler metal added. Heat Treatment As a final heat treatment, tubes shall be reheated to a temperature of 1200 °F [650 °C] or higher and cooled (as appropriate for the grade) to meet the requirements of this specification. The martensitic grade UNS S 41500 shall be reheated to a temperature of 950 °F [510 °C] or higher and cooled as appropriate to meet the requirements of this specification. Surface Condition All tubes shall be free of excessive mill scale, suitable for inspection. A slight amount of oxidation will not be considered as scale. Any special finish requirements shall be subject to agreement between the manufacturer and the purchaser. Product Marking In addition to the marking described in Specification A1016/A1016M, the marking shall indicate whether the tubing is seamless or welded. Marking Sample: LINKUN ASTM A268/A268M UNS S44400 SMLS 44.5 X 4 X 12000MM HEAT NO. XXXXXX MADE IN CHINA Packing 1. Covered with seaworthy bags, hexagonal bundled. 2. Packed in plywood boxes/wooden crates. 3. Packed in steel-framed boxes. Linkun is one of the leading China Stainless Steel Pipe And Tube manufacturers and suppliers, if you want to buy or import best high-quality astm a268 stainless steel tubing professional company, factory, seller, and exporter, or if you are checking steel brands, please feel free to contact us.
ASTM A268/A268M Stainless Steel Tubing Hardness requirements: 
Manufacture The tubes shall be made by the seamless or welded process with no filler metal added. Heat Treatment As a final heat treatment, tubes shall be reheated to a temperature of 1200 °F [650 °C] or higher and cooled (as appropriate for the grade) to meet the requirements of this specification. The martensitic grade UNS S 41500 shall be reheated to a temperature of 950 °F [510 °C] or higher and cooled as appropriate to meet the requirements of this specification. Surface Condition All tubes shall be free of excessive mill scale, suitable for inspection. A slight amount of oxidation will not be considered as scale. Any special finish requirements shall be subject to agreement between the manufacturer and the purchaser. Product Marking In addition to the marking described in Specification A1016/A1016M, the marking shall indicate whether the tubing is seamless or welded. Marking Sample: LINKUN ASTM A268/A268M UNS S44400 SMLS 44.5 X 4 X 12000MM HEAT NO. XXXXXX MADE IN CHINA Packing 1. Covered with seaworthy bags, hexagonal bundled. 2. Packed in plywood boxes/wooden crates. 3. Packed in steel-framed boxes. Linkun is one of the leading China Stainless Steel Pipe And Tube manufacturers and suppliers, if you want to buy or import best high-quality astm a268 stainless steel tubing professional company, factory, seller, and exporter, or if you are checking steel brands, please feel free to contact us. 
