ASTM International - ASTM A268/A268M-20

Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service

active

Organization:	ASTM International
Publication Date:	1 March 2020
Status:	active
Page Count:	7
ICS Code (Iron and steel pipes):	23.040.10

scope:

1.1 This specification2 covers a number of grades of nominal-wall-thickness, stainless steel tubing for general corrosion-resisting and high-temperature service. Most of these grades are commonly known as the "straight-chromium" types and are characterized by being ferromagnetic. Two of these grades, TP410 and UNS S 41500 (Table 1), are amenable to hardening by heat treatment, and the high-chromium, ferritic alloys are sensitive to notch-brittleness on slow cooling to ordinary temperatures. These features should be recognized in the use of these materials.

TABLE 1 Continued
Grade	TP439	. . .	. . .	TP430 Ti	TP XM-27	TP XM-33 ^A	18Cr-2Mo	29-4	29-4-2	26-3-3	25-4-4	...	. . .	. . .	. . .	. . .	TP468
UNS Designation	S43035	S43932	S41500 ^B	S43036	S44627	S44626	S44400	S44700	S44800	S44660	S44635	S44735	S32803	S40977	S43940	S42035	S46800
Element	Composition, %
C, max	0.07	0.030	0.05	0.10	0.01 ^A	0.06	0.025	0.010	0.010	0.030	0.025	0.030	0.015 ^C	0.03	0.03	0.08	0.030
Mn, max	1.00	1.00	0.5-1.0	1.00	0.40	0.75	1.00	0.30	0.30	1.00	1.00	1.00	0.5	1.50	1.00	1.00	1.00
P, max	0.040	0.040	0.03	0.040	0.02	0.040	0.040	0.025	0.025	0.040	0.040	0.040	0.020	0.040	0.040	0.045	0.040
S, max	0.030	0.030	0.03	0.030	0.02	0.020	0.030	0.020	0.020	0.030	0.030	0.030	0.005	0.015	0.015	0.030	0.030
Si, max	1.00	1.00	0.60	1.00	0.40	0.75	1.00	0.20	0.20	1.00	0.75	1.00	0.50	1.00	1.00	1.00	1.00
Ni	0.50 max	0.50	3.5-5.5	0.75 max	0.5 ^D max	0.50 max	1.00 max	0.15 max	2.0-2.5	1.0-3.50	3.5-4.5	1.00 max	3.0-4.0	0.30-1.00	. . .	1.0-2.5	0.50
Cr	17.00-	17.0-19.0	11.5-14.0	16.00-	25.0-27.5	25.0-27.0	17.5-19.5	28.0-30.0	28.0-30.0	25.0-28.0	24.5-26.0	28.00-	28.0- 29.0	10.50- 12.50	17.50- 18.50	13.5- 15.5	18.00- 20.00
	19.00			19.50								30.00
Mo	...	...	0.5-1.0	...	0.75-1.50	0.75-1.50	1.75-2.50	3.5-4.2	3.5-4.2	3.0-4.0	3.5-4.5	3.60-4.20	1.8-2.5	. . .	. . .	0.2-1.2	. . .
Al, max	0.15	0.15	. . .	...	...	...	...	...	...	...	...	...	. . .	. . .	. . .	. . .	. . .
Cu, max	...	...	. . .	...	0.2	0.20	...	0.15	0.15	...	...	...	. . .	. . .	. . .	. . .	. . .
N, max	0.04	0.030 (Ti + Cb) {0.20 + 4 (C + N)} min.; 0.75 max	. . .	...	0.015	0.040	0.035	0.020 ^E	0.020 ^E	0.040	0.035	0.045	0.020	0.030	. . .	. . .	0.030
Ti	0.20 + 4 (C		. . .	5 × C min;	...	7 × (C + N)	(Ti + Cb)	...	...	(Ti + Cb) =	(Ti + Cb) =	(Ti + Cb) =	. . .	. . .	0.10-0.60	0.30-0.50	0.07-0.30
	+ N) min;			0.75 max		but no less	0.20 + 4			0.20-1.00	0.20 + 4	0.20-1.00
	1.10 max					than 0.20	(C + N)			and 6 ×	(C + N)	and 6 ×
						min; 1.00	min; 0.80			(C + N)	min to	(C+ N)
						max	max			min	0.80 max	min

Cb	...		. . .	...	0.05-0.20	...	...	...	...	...	...	...	0.15- 0.50 ^F	. . .	(3 × %C + 0.30) min	. . .	0.10-0.60
																	(Ti + Cb) =
																	0.20 +4(C+N)
																	min;0.80 max

1.2 An optional supplementary requirement is provided, and when desired, shall be so stated in the order.

1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound units shall apply unless the "M" designation of this specification is specified in the order.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

abstract:

This guide covers standard specification for a number of grades of nominal-wall-thickness, welded ferritic and martensitic stainless steel tubing for general corrosion-resisting and... View More