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.