Material composition

What is stainless steel made of? Composition of 30+ grades

Stainless steel is an iron-based alloy that contains chromium: across the 37 stainless steel profiles in the Space Mushroom database, the printed chromium limits run from 10.500 wt% minimum for Stainless steel 409 (UNS S40900, per ICAST) to 26 wt% maximum for Stainless steel 310S (UNS S31008, per Atlas Steels). Nickel limits reach 28 wt% and molybdenum limits reach 5 wt%, both for Super-austenitic stainless steel 904L (UNS N08904, per Sandmeyer); the highest carbon limit is 1.20 wt% for Stainless steel 440C (UNS S44004, per Rolled Alloys). Nitrogen, manganese, silicon, copper, titanium, niobium and aluminium are added in some families.

Weight percent (wt%) is the share of the alloy's mass. "max" means the source prints only an upper limit, "nominal" means it prints a target value instead of limits, and a dash means no limit is printed. Each limit comes from one cited source per grade (ASTM A240, EN 10088 or a mill datasheet), so it is a specification limit, not the analysis of a particular heat.

Space Mushroom · data checked 2 November 2026 · 37 profiles · download the data (CSV) · jump to the mill-certificate matcher

What is stainless steel made of?

Stainless steel is made of iron alloyed with chromium and, depending on the family, nickel, molybdenum, nitrogen, manganese and carbon. Across the 37 grades in our data, chromium limits run from 10.500 to 26 wt%, nickel limits reach 28 wt% and molybdenum limits reach 5 wt%, each as printed in the datasheet or standard cited on the grade's profile page.

The table gives the span for each family. Open the sections below for every grade, or go straight to the matcher with your own certificate values.

Chromium, nickel, molybdenum, carbon and nitrogen limits by stainless steel family, wt% (lowest printed minimum to highest printed maximum; "up to" where some grades print only a maximum)
Family	Grades	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%
Austenitic stainless steels	16	16.0 to 26	6.0 to 28	up to 56 of 16 grades	up to 0.20	up to 0.209 of 16 grades
Ferritic stainless steels	4	10.500 to 19.5	up to 1.003 of 4 grades	up to 2.50	up to 0.12	up to 0.0351 of 4 grades
Martensitic stainless steels	8	11.5 to 18.0	up to 6.005 of 8 grades	up to 1.504 of 8 grades	up to 1.20	min 0.021 of 8 grades
Duplex stainless steels	4	21.0 to 25*	1.35 to 7*	0.05 to 4*	up to 0.040	0.05 to 0.3*
Precipitation-hardening stainless steels	5	11.00 to 18.00	3.0 to 11.25	0.75 to 3.002 of 5 grades	up to 0.09	up to 0.011 of 5 grades
All 37 grades	37	10.500 to 26	up to 2833 of 37 grades	up to 520 of 37 grades	up to 1.20	up to 0.3*16 of 37 grades

* A nominal value is printed, not a limit. A dash or "none printed" means the cited source prints no limit for that element; it does not mean the element is absent.

Austenitic (16 grades): chromium 16.0 to 26 wt%; nickel 6.0 to 28 wt%; molybdenum up to 5 wt% (6 of 16 grades); nitrogen up to 0.20 wt% (9 of 16 grades).
Ferritic (4 grades): chromium 10.500 to 19.5 wt%; nickel up to 1.00 wt% (3 of 4 grades); molybdenum up to 2.50 wt%; nitrogen up to 0.035 wt% (1 of 4 grades).
Martensitic (8 grades): chromium 11.5 to 18.0 wt%; nickel up to 6.00 wt% (5 of 8 grades); molybdenum up to 1.50 wt% (4 of 8 grades); nitrogen min 0.02 wt% (1 of 8 grades).
Duplex (4 grades): chromium 21.0 to 25 wt%*; nickel 1.35 to 7 wt%*; molybdenum 0.05 to 4 wt%*; nitrogen 0.05 to 0.3 wt%*.
Precipitation hardening (5 grades): chromium 11.00 to 18.00 wt%; nickel 3.0 to 11.25 wt%; molybdenum 0.75 to 3.00 wt% (2 of 5 grades); nitrogen up to 0.01 wt% (1 of 5 grades).

Which stainless steel grade matches my mill certificate?

To find which stainless steel grade matches a mill certificate, enter its chromium, nickel, molybdenum and carbon values in wt% and read the grades whose printed limits contain every value. For example, the mid-limits of Stainless steel 316L (UNS S31603) (Cr 17, Ni 12, Mo 2.5, C 0.015 wt%) are contained in the limits of 2 grades: Stainless steel 316 and Stainless steel 316L.

Each field is optional. A grade is a match when every value you enter lies inside its printed limits (a maximum alone means 0 up to the maximum). A grade that misses a value by a small margin, or fits only under another source's limits, is listed as "close, check the standard". The ribbon below the matcher shows your values on the same scales.

Worked example: the mid-limits of Stainless steel 316L (UNS S31603)

Entered: Cr 17, Ni 12, Mo 2.5, C 0.015 wt%, the middle of each limit that the profile prints for that grade (half of a maximum). 2 of 37 grades contain all 4 values and 0 more are close; 35 are ruled out. Data checked 2 November 2026.

Grades whose printed limits contain Cr 17, Ni 12, Mo 2.5, C 0.015 wt%
Grade	Family	UNS or EN	Printed limits for the entered elements, wt%	Source
Stainless steel 316	Austenitic	S31600	Cr 16 to 18; Ni 10 to 14; Mo 2 to 3; C max 0.08	UPMET
Stainless steel 316L	Austenitic	S31603	Cr 16.0 to 18.0; Ni 10.0 to 14.0; Mo 2.00 to 3.00; C max 0.030	Combined Metals

How the matcher decides, and what it leaves out

Inside the limits. A value matches when it is at or above the printed minimum and at or below the printed maximum, in wt%. A "max" limit alone allows 0 up to the maximum.
No limit printed. If the cited source prints no limit for an element, only a blank or a value of 0 is accepted for it; a small value is listed as close.
Nominal values. Where a source prints a target and no limits (stainless steel 2507 for chromium, nickel, molybdenum and nitrogen), the grade can only be close, never an exact match.
Close. A value is close when it misses a limit by no more than chromium 0.5, nickel 0.5, molybdenum 0.2, carbon 0.01 wt%, or fits inside the limits another source prints for the same grade. These margins are this page's own, not tolerances from a standard.
Left out. Nitrogen, manganese, silicon and the other elements, product-analysis tolerances, and the heat treatment or product form are not matched. Use the standard in your purchase order for acceptance.

How do chromium, nickel and molybdenum differ between stainless steel families?

Chromium, nickel and molybdenum limits separate the families: ferritic stainless steels print chromium 10.500 to 19.5 wt% and nickel up to 1.00 wt%, austenitic stainless steels add nickel 6.0 to 28 wt% and duplex stainless steels print nickel 1.35 to 7 wt%* with nitrogen 0.05 to 0.3 wt%*, per the datasheets and standards cited on each profile page. Martensitic and precipitation-hardening grades sit between these groups, and molybdenum is printed for only 20 of 37 grades.

One row per grade. A solid bar runs from the printed minimum to the printed maximum; a bar that fades to the left prints only a maximum; a diamond is a nominal value; the dashed line under a bar is the range another source prints. Names link to the grade's profile. The same numbers are in the composition tables below.

Sort rows by

Austenitic stainless steels 16 grades
304 S30400Austenitic

Cr 17.5 to 20
Ni 8 to 11
Mo no limit printed
301 S30100Austenitic

Cr 16.0 to 18.0
Ni 6.0 to 8.0
Mo no limit printed
303 S30300Austenitic

Cr 17.0 to 19.0
Ni 8.0 to 10.0
Mo max 0.6
316 S31600Austenitic

Cr 16 to 18
Ni 10 to 14
Mo 2 to 3
316L S31603Austenitic

Cr 16.0 to 18.0
Ni 10.0 to 14.0
Mo 2.00 to 3.00
302 S30200Austenitic

Cr 17.0 to 19.0
Ni 8.0 to 10.0
Mo no limit printed
304L S30403Austenitic

Cr 18.0 to 20.0 · other source: 17.5 to 19.5 (ATI 304L page)
Ni 8.0 to 12.0
Mo no limit printed
309 S30900Austenitic

Cr 22.00 to 24.00
Ni 12.00 to 15.00
Mo no limit printed
310S S31008Austenitic

Cr 24 to 26
Ni 19 to 22
Mo no limit printed
317L S31703Austenitic

Cr 18 to 20
Ni 11 to 15
Mo 3 to 4
321 S32100Austenitic

Cr 17.0 to 19.0
Ni 9.0 to 12.0
Mo no limit printed
347 S34700Austenitic

Cr 17.00 to 19.00
Ni 9.00 to 13.00 · other source: 9.00 to 12.00 (UPMET and Combmet)
Mo no limit printed
347H S34709Austenitic

Cr 17.0 to 19.0
Ni 9.0 to 13.0
Mo no limit printed
904L N08904Austenitic

Cr 19 to 23 · other source: 19.8 (typical) (Outokumpu typical analysis)
Ni 23 to 28 · other source: 24.2 (typical) (Outokumpu typical analysis)
Mo 4 to 5 · other source: 4.3 (typical) (Outokumpu typical analysis)
Nitronic 60 S21800Austenitic

Cr 16.0 to 18.0
Ni 8.0 to 9.0
Mo no limit printed
317LMN S31726Austenitic

Cr 17.0 to 20.0
Ni 13.5 to 17.5
Mo 4.0 to 5.0
Ferritic stainless steels 4 grades
430 S43000Ferritic

Cr 16.0 to 18.0
Ni max 0.75
Mo max 0.50
409 S40900Ferritic

Cr 10.500 to 11.750 · other source: 10.50 to 11.70 (Combined Metals (for UNS S40910, S40920 and S40930)); 10.50 to 12.50 (EN 10088-2 limits (Aalco))
Ni max 0.500
Mo max 0.350
444 S44400Ferritic

Cr 17.5 to 19.5
Ni max 1.00
Mo 1.75 to 2.50 · other source: 1.8 to 2.5 (Ugitech)
430F S43020Ferritic

Cr 16.0 to 18.0 · other source: 15.5 to 17.5 (EN 1.4104 (Deutsche Edelstahlwerke))
Ni no limit printed
Mo max 0.60 · other source: 0.20 to 0.60 (EN 1.4104 (Deutsche Edelstahlwerke))
Martensitic stainless steels 8 grades
410 S41000Martensitic

Cr 11.5 to 13.5
Ni max 0.75
Mo no limit printed
440C S44004Martensitic

Cr 16.0 to 18.0
Ni no limit printed
Mo max 0.75 · other source: 0.40 to 0.80 (EN 10088-3 (Aalco))
S41500 S41500Martensitic

Cr 11.5 to 14.0
Ni 3.5 to 5.5
Mo 0.5 to 1.0
410S S41008Martensitic

Cr 11.5 to 13.5
Ni max 0.6
Mo no limit printed
416 S41600Martensitic

Cr 12.0 to 14.0
Ni no limit printed
Mo max 0.60
420 S42000Martensitic

Cr 12.0 to 14.0
Ni no limit printed
Mo no limit printed
431 S43100Martensitic

Cr 15.0 to 17.0
Ni 1.5 to 2.5
Mo no limit printed
1.4418 EN 1.4418Martensitic

Cr 15.00 to 17.00
Ni 4.00 to 6.00
Mo 0.80 to 1.50
Duplex stainless steels 4 grades
2205 S32205Duplex

Cr 22.0 to 23.0
Ni 4.5 to 6.5
Mo 3.0 to 3.5
2507 S32750Duplex

Cr 25 (nominal)
Ni 7 (nominal)
Mo 4 (nominal)
2304 S32304Duplex

Cr 21.5 to 24.5
Ni 3.0 to 5.5
Mo 0.05 to 0.60
2101 S32101Duplex

Cr 21.0 to 22.0
Ni 1.35 to 1.70
Mo 0.10 to 0.80
Precipitation-hardening stainless steels 5 grades
17-4 PH S17400Precipitation hardening

Cr 15.0 to 17.5
Ni 3.0 to 5.0
Mo no limit printed
17-7 PH S17700Precipitation hardening

Cr 16.00 to 18.00
Ni 6.50 to 7.75
Mo no limit printed
15-7 PH S15700Precipitation hardening

Cr 14.00 to 16.00
Ni 6.50 to 7.75
Mo 2.00 to 3.00
15-5 PH S15500Precipitation hardening

Cr 14.00 to 15.50
Ni 3.50 to 5.50
Mo no limit printed
Custom 465 S46500Precipitation hardening

Cr 11.00 to 12.50
Ni 10.75 to 11.25
Mo 0.75 to 1.25

printed minimum to maximum
maximum only
nominal value
other source's range
your value from the matcher

What is the chemical composition of each stainless steel grade?

Stainless steel 316L (UNS S31603) is specified at 16.0 to 18.0 wt% chromium, 10.0 to 14.0 wt% nickel, 2.00 to 3.00 wt% molybdenum and at most 0.030 wt% carbon (per Combined Metals). Stainless steel 430 (UNS S43000) prints 16.0 to 18.0 wt% chromium and at most 0.75 wt% nickel (per ATI); Duplex stainless steel 2205 (UNS S32205) prints 22.0 to 23.0 wt% chromium and 4.5 to 6.5 wt% nickel (per ICAST).

Limits are in wt%, iron is the balance, and each row names the source of its limits. Other elements are in the CSV.

What is the composition of austenitic stainless steels?

Composition limits of austenitic stainless steels, wt% (iron balance; "max" is an upper limit only; "–" means no limit printed)
Grade	UNS or EN	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%	Mn, wt%	Si, wt%	Other elements, wt%	Source
Stainless steel 304	S30400	17.5 to 20	8 to 11	–	max 0.08	–	–	–	–	AZoM
Stainless steel 301	S30100	16.0 to 18.0	6.0 to 8.0	–	max 0.15	max 0.10	max 2.00	max 1.00	–	UPMET
Stainless steel 303	S30300	17.0 to 19.0	8.0 to 10.0	max 0.6	max 0.15	–	max 2.0	max 1.0	S min 0.15	Rolled Alloys
Stainless steel 316	S31600	16 to 18	10 to 14	2 to 3	max 0.08	max 0.10	max 2	max 0.75	–	UPMET
Stainless steel 316L	S31603	16.0 to 18.0	10.0 to 14.0	2.00 to 3.00	max 0.030	max 0.10	max 2.00	max 0.75	–	Combined Metals
AISI 302 stainless steel (UNS S30200, EN 1.4310)	S30200	17.0 to 19.0	8.0 to 10.0	–	max 0.15	max 0.10	max 2.0	max 0.75	–	Elgiloy
Stainless steel 304L	S30403	18.0 to 20.0	8.0 to 12.0	–	max 0.030	max 0.10	max 2.00	max 0.75	–	ICAST
AISI 309 stainless steel	S30900	22.00 to 24.00	12.00 to 15.00	–	max 0.20	–	max 2.00	max 0.75	–	Jacquet
Stainless steel 310S	S31008	24 to 26	19 to 22	–	max 0.08	–	max 2.00	max 1.50	–	Atlas Steels
AISI 317L stainless steel	S31703	18 to 20	11 to 15	3 to 4	max 0.03	max 0.10	max 2.0	max 0.75	–	ATI
AISI 321 stainless steel (UNS S32100, EN 1.4541)	S32100	17.0 to 19.0	9.0 to 12.0	–	max 0.08	max 0.10	max 2.00	max 0.75	Ti 5 x (C+N) to 0.70	ATI
AISI 347 stainless steel	S34700	17.00 to 19.00	9.00 to 13.00	–	max 0.08	–	max 2.00	–	Nb+Ta 10 x C min to 1.00 max	Aalco
AISI 347H stainless steel	S34709	17.0 to 19.0	9.0 to 13.0	–	0.04 to 0.10	–	max 2.0	max 0.75	Nb+Ta 8 x C min to 1.0 max	a tubing supplier
Super-austenitic stainless steel 904L	N08904	19 to 23	23 to 28	4 to 5	max 0.02	–	max 2	max 1	Cu 1 to 2	Sandmeyer
Nitronic 60 stainless steel	S21800	16.0 to 18.0	8.0 to 9.0	–	max 0.10	0.08 to 0.18	7.0 to 9.0	3.5 to 4.5	–	Rolled Alloys
AISI 317LMN stainless steel	S31726	17.0 to 20.0	13.5 to 17.5	4.0 to 5.0	max 0.030	0.10 to 0.20	max 2.00	max 0.75	–	ATI

What is the composition of ferritic stainless steels?

Composition limits of ferritic stainless steels, wt% (iron balance; "max" is an upper limit only; "–" means no limit printed)
Grade	UNS or EN	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%	Mn, wt%	Si, wt%	Other elements, wt%	Source
Stainless steel 430	S43000	16.0 to 18.0	max 0.75	max 0.50	max 0.12	–	max 1.00	max 1.00	–	ATI
Stainless steel 409	S40900	10.500 to 11.750	max 0.500	max 0.350	max 0.080	–	max 1.000	max 1.000	Cu max 0.350; Ti max 0.750	ICAST
Stainless steel 444	S44400	17.5 to 19.5	max 1.00	1.75 to 2.50	max 0.025	max 0.035	max 1.00	max 1.00	Nb+Ta 0.20 + 4 x (C+N) to 0.80	ATI
Stainless steel 430F	S43020	16.0 to 18.0	–	max 0.60	max 0.12	–	max 1.25	max 1.00	S min 0.15	Atlas Steels

What is the composition of martensitic stainless steels?

Composition limits of martensitic stainless steels, wt% (iron balance; "max" is an upper limit only; "–" means no limit printed)
Grade	UNS or EN	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%	Mn, wt%	Si, wt%	Other elements, wt%	Source
Stainless steel 410	S41000	11.5 to 13.5	max 0.75	–	0.08 to 0.15	–	max 1.0	max 1.0	–	Rolled Alloys
Stainless steel 440C	S44004	16.0 to 18.0	–	max 0.75	0.95 to 1.20	–	max 1.00	max 1.00	–	Rolled Alloys
Martensitic stainless steel 13Cr-4Ni (UNS S41500)	S41500	11.5 to 14.0	3.5 to 5.5	0.5 to 1.0	max 0.050	–	0.5 to 1.0	max 0.600	–	ICAST
Stainless steel 410S	S41008	11.5 to 13.5	max 0.6	–	max 0.08	–	max 1.0	max 1.0	Ti max 0.20	Rolled Alloys
AISI 416 stainless steel	S41600	12.0 to 14.0	–	max 0.60	max 0.15	–	max 1.25	max 1.0	S min 0.15	Rolled Alloys
Stainless steel 420	S42000	12.0 to 14.0	–	–	0.16 to 0.25	–	–	–	–	Team Edelstahl
Stainless steel 431	S43100	15.0 to 17.0	1.5 to 2.5	–	0.12 to 0.22	–	max 1.5	max 1.0	–	Team Edelstahl
Martensitic stainless steel (EN 1.4418, X4CrNiMo16-5-1)	EN 1.4418	15.00 to 17.00	4.00 to 6.00	0.80 to 1.50	max 0.06	min 0.02	max 1.5	max 0.7	–	Deutsche Edelstahlwerke

What is the composition of duplex stainless steels?

Composition limits of duplex stainless steels, wt% (iron balance; "max" is an upper limit only; "–" means no limit printed)
Grade	UNS or EN	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%	Mn, wt%	Si, wt%	Other elements, wt%	Source
Duplex stainless steel 2205	S32205	22.0 to 23.0	4.5 to 6.5	3.0 to 3.5	max 0.030	0.14 to 0.20	max 2.0	max 1.0	–	ICAST
Super duplex stainless steel 2507	S32750	25 (nominal)	7 (nominal)	4 (nominal)	max 0.03	0.3 (nominal)	max 1.2	max 0.8	Cu max 0.5	Alleima
Lean duplex stainless steel 2304	S32304	21.5 to 24.5	3.0 to 5.5	0.05 to 0.60	max 0.030	0.05 to 0.20	max 2.50	max 1.00	Cu 0.05 to 0.60	ICAST
Lean duplex stainless steel 2101 (UNS S32101)	S32101	21.0 to 22.0	1.35 to 1.70	0.10 to 0.80	max 0.040	0.20 to 0.25	4.00 to 6.00	max 1.00	Cu 0.10 to 0.80	Atlas Steels

What is the composition of precipitation-hardening stainless steels?

Composition limits of precipitation-hardening stainless steels, wt% (iron balance; "max" is an upper limit only; "–" means no limit printed)
Grade	UNS or EN	Cr, wt%	Ni, wt%	Mo, wt%	C, wt%	N, wt%	Mn, wt%	Si, wt%	Other elements, wt%	Source
17-4 PH stainless steel	S17400	15.0 to 17.5	3.0 to 5.0	–	max 0.070	–	max 1.00	max 1.00	Cu 3.0 to 5.0; Nb+Ta 0.15 to 0.45	Carpenter
17-7 PH stainless steel	S17700	16.00 to 18.00	6.50 to 7.75	–	max 0.09	–	max 1.00	max 1.00	Al 0.75 to 1.50	Cleveland-Cliffs
PH 15-7 Mo stainless steel	S15700	14.00 to 16.00	6.50 to 7.75	2.00 to 3.00	max 0.09	–	max 1.00	max 1.00	Al 0.75 to 1.50	ATI
15-5 PH stainless steel	S15500	14.00 to 15.50	3.50 to 5.50	–	max 0.07	–	max 1.00	max 1.00	Cu 2.50 to 4.50; Nb+Ta 0.15 to 0.45	Service Steel Aerospace
Custom 465 stainless steel	S46500	11.00 to 12.50	10.75 to 11.25	0.75 to 1.25	max 0.02	max 0.01	max 0.25	max 0.25	Ti 1.50 to 1.80; Al 0.90 to 1.35	Service Steel Aerospace

Values are printed exactly as the cited source gives them, so decimals differ between grades. A value after "max" in a list headed "max" is read as a maximum. Phosphorus and sulphur limits (and the other sources' limits) are in the CSV.

Do sources print different composition limits for the same stainless steel?

Yes. Sources print different composition limits for the same grade in 7 of 37 profiles. For Stainless steel 304L (UNS S30403), ICAST prints 18.0 to 20.0 wt% chromium and the ATI 304L page prints 17.5 to 19.5 wt%. For Stainless steel 409 (UNS S40900), ICAST prints 10.500 to 11.750 wt% chromium and Combined Metals (for UNS S40910, S40920 and S40930) prints 10.50 to 11.70 wt%.

Both values are shown side by side. Use the limits of the standard named in your purchase order; the matcher lists a grade that fits only the other source's limits as "close".

Composition limits that differ between sources for the same grade, wt%
Grade	Element	Main source, wt%	Other source or analysis, wt%	Other source
Stainless steel 304L	chromium	18.0 to 20.0 ICAST	17.5 to 19.5	ATI 304L page
AISI 347 stainless steel	nickel	9.00 to 13.00 Aalco	9.00 to 12.00	UPMET and Combmet
Super-austenitic stainless steel 904L	chromium	19 to 23 Sandmeyer	19.8 (typical)	Outokumpu typical analysis (typical analysis, not a limit)
Super-austenitic stainless steel 904L	nickel	23 to 28 Sandmeyer	24.2 (typical)	Outokumpu typical analysis (typical analysis, not a limit)
Super-austenitic stainless steel 904L	molybdenum	4 to 5 Sandmeyer	4.3 (typical)	Outokumpu typical analysis (typical analysis, not a limit)
Super-austenitic stainless steel 904L	copper	1 to 2 Sandmeyer	1.4 (typical)	Outokumpu typical analysis (typical analysis, not a limit)
Super-austenitic stainless steel 904L	carbon	max 0.02 Sandmeyer	0.01 (typical)	Outokumpu typical analysis (typical analysis, not a limit)
Stainless steel 409	chromium	10.500 to 11.750 ICAST	10.50 to 11.70	Combined Metals (for UNS S40910, S40920 and S40930)
Stainless steel 409	carbon	max 0.080 ICAST	max 0.030	Combined Metals (for UNS S40910, S40920 and S40930)
Stainless steel 409	nitrogen	no limit printed ICAST	max 0.030	Combined Metals (for UNS S40910, S40920 and S40930)
Stainless steel 409	chromium	10.500 to 11.750 ICAST	10.50 to 12.50	EN 10088-2 limits (Aalco)
Stainless steel 444	molybdenum	1.75 to 2.50 ATI	1.8 to 2.5	Ugitech
Stainless steel 444	nitrogen	max 0.035 ATI	max 0.03	Ugitech
Stainless steel 444	sulphur	max 0.030 ATI	max 0.015	Ugitech
Stainless steel 430F	chromium	16.0 to 18.0 Atlas Steels	15.5 to 17.5	EN 1.4104 (Deutsche Edelstahlwerke)
Stainless steel 430F	carbon	max 0.12 Atlas Steels	0.10 to 0.17	EN 1.4104 (Deutsche Edelstahlwerke)
Stainless steel 430F	molybdenum	max 0.60 Atlas Steels	0.20 to 0.60	EN 1.4104 (Deutsche Edelstahlwerke)
Stainless steel 430F	sulphur	min 0.15 Atlas Steels	0.15 to 0.35	EN 1.4104 (Deutsche Edelstahlwerke)
Stainless steel 440C	molybdenum	max 0.75 Rolled Alloys	0.40 to 0.80	EN 10088-3 (Aalco)

What do these compositions change in strength, density and expansion?

Composition sets the family, and the family sets the range, but heat treatment and product form decide where a grade sits inside it. At room temperature or with no temperature stated, our yield strength records run from 170 MPa (Stainless steel 316L, as printed) to 1,896 MPa (Stainless steel 440C, as printed), so every value below keeps its own condition and source.

The strength table shows the lowest and highest record at room temperature (or with no temperature stated) in each family, each with its own grade, condition and source: they are not the same temper, form or test, so the two ends of a row are not a range for one material. Values printed in ksi are converted to MPa (1 ksi = 6.894757 MPa).

Lowest and highest strength record in each family at room temperature or with no temperature stated, MPa, with the condition of each record
Family	Property	Lowest record	Highest record	Records
Austenitic	Yield strength (0.2% offset)	170 MPaStainless steel 316L · as printed · form: plate, sheet, strip; basis: minimum value as printed; offset not stated on this page; temper: not stated · per ATI	1,103 MPaStainless steel 301 · as printed · temper: full hard (as rolled); orientation: longitudinal; basis: typical · per ATI	55
Austenitic	Tensile strength	480 MPaStainless steel 316 · as printed · form: not stated; temper: not stated; temperature: not stated · per AZoM	2,200 MPaAISI 302 stainless steel (UNS S30200, EN 1.4310) · range · temper: spring temper; basis: approximate, as supplied · per Alloy Wire International	48
Ferritic	Yield strength (0.2% offset)	170 MPaStainless steel 409 · minimum · form: 409 sheet, ASTM A240 basis (Combined Metals data sheet); temper: annealed (Min); temperature: room temperature (typical r... · per Combined Metals	500 MPaStainless steel 430F · minimum · form: 1.4104 bar, quench and tempered to QT650; temper: QT650 (hardened 950 to 1070 C, tempered 550 to 650 C); temperature: roo... · per Deutsche Edelstahlwerke	16
Ferritic	Tensile strength	380 MPaStainless steel 409 · minimum · form: 409 sheet, ASTM A240 basis (Combined Metals data sheet); temper: annealed (Min); temperature: room temperature (typical r... · per Combined Metals	850 MPaStainless steel 430F · range · form: 1.4104 bar, quench and tempered to QT650; temper: QT650 (hardened 950 to 1070 C, tempered 550 to 650 C); temperature: roo... · per Deutsche Edelstahlwerke	16
Martensitic	Yield strength (0.2% offset)	205 MPaStainless steel 410 · range · condition: A (annealed); basis: typical range, printed as 30 (205) to 42 (290) ksi (MPa) · per UPMET	1,896 MPaStainless steel 440C · as printed (printed 275 ksi) · heat treatment: hardened 1900 F, oil quench, tempered 600 F; temperature: 70 F; basis: 0.2 percent offset yield, as printed · per Rolled Alloys	41
Martensitic	Tensile strength	414 MPaStainless steel 410S · minimum (printed 60 ksi) · condition: not printed; basis: minimum, plate · per Rolled Alloys	1,965 MPaStainless steel 440C · as printed (printed 285 ksi) · heat treatment: hardened 1900 F, oil quench, tempered 600 F; temperature: 70 F · per Rolled Alloys	42
Duplex	Yield strength (0.2% offset)	400 MPaLean duplex stainless steel 2304 · minimum · form: ATI 2304 plate, ASTM A240 minimum; heat treatment: annealed (ASTM A240 minimum); temperature: room temperature · per ATI	895 MPaDuplex stainless steel 2205 · minimum · form: seamless tube and pipe, cold worked for oil and gas production; heat treatment: cold worked, no subsequent heat treatment... · per Alleima	9
Duplex	Tensile strength	600 MPaLean duplex stainless steel 2304 · minimum · form: ATI 2304 plate, ASTM A240 minimum; heat treatment: annealed (ASTM A240 minimum); temperature: room temperature · per ATI	1,000 MPaSuper duplex stainless steel 2507 · range · form: seamless tube and pipe, wall up to 20 mm; temper: solution annealed and quenched; temperature: 20 °C · per Alleima	10
Precipitation hardening	Yield strength (0.2% offset)	310 MPa17-7 PH stainless steel · as printed · condition: A (annealed); basis: typical, room temperature; form: not stated in table · per Cleveland-Cliffs	1,896 MPa17-7 PH stainless steel · as printed · condition: CH 900; basis: typical, room temperature; form: not stated in table · per Cleveland-Cliffs	23
Precipitation hardening	Tensile strength	827 MPa17-7 PH stainless steel · as printed · condition: A (annealed); basis: typical, room temperature; form: not stated in table · per Cleveland-Cliffs	2,034 MPa17-7 PH stainless steel · as printed · condition: CH 900; basis: typical, room temperature; form: not stated in table · per Cleveland-Cliffs	23

Density and mean thermal expansion by family: lowest and highest record, with the grade that prints it
Family	Density, g/cm3 (records at 20 °C or temperature not stated)	Mean thermal expansion, 10^-6/K (0, 20 or 30 to 100 °C)
Austenitic	7.8 (310S) to 8.09 (321)29 records	15.3 (904L) to 17.3 (302)17 records
Ferritic	7.6 (409) to 7.75 (409)9 records	10 (430F) to 10.5 (409)5 records
Martensitic	7.61 (S41500) to 8.1 (S41500)15 records	9.9 (410) to 10.8 (410S)7 records
Duplex	7.8 (2205) to 7.82 (2205)6 records	13 (2205) to 13.5 (2507)5 records
Precipitation hardening	7.65 (17-7 PH) to 7.86 (17-4 PH)10 records	not found in any source we hold

Can the composition be turned into a pitting-resistance number?

The pitting resistance equivalent number (PREN) is a figure computed from chromium, molybdenum and nitrogen content. Our data holds a PREN for only 2 profiles (904L and 2507), listed below with the basis each source gives. We do not compute PREN from the limits on this page, so the other 35 grades have none. For marine selection see stainless steel for seawater.

Pitting resistance equivalent number (PREN) records in the database, dimensionless
Grade	PREN	Kind	Conditions and basis as printed	Source
Super-austenitic stainless steel 904L	34	as printed	grade: Ultra 904L (EN 1.4539); basis: Outokumpu typical composition, PRE = %Cr + 3.3 x %Mo + 16 x %N	Outokumpu
Super duplex stainless steel 2507	42.5	minimum	form: seamless tube and pipe; temperature: not stated; basis: minimum PRE; PRE = %Cr + 3.3 x %Mo + 16 x %N	Alleima
Super duplex stainless steel 2507	41	minimum	form: general minimum for SAF 2507, product form not stated; temperature: not stated; basis: minimum PRE; PRE = %Cr + 3.3 x %Mo + 16 x %N	Alleima

How much chromium does steel need to be stainless?

Steel is generally called stainless when it holds at least about 10.5 wt% chromium (general engineering knowledge, not in our data). The lowest chromium minimum printed in our data is 10.500 wt% for Stainless steel 409 (UNS S40900, per ICAST), and all 37 grades that print a chromium limit or nominal value print at least that much.

Chromium forms a thin oxide film on the surface that resists corrosion, and nickel, molybdenum and nitrogen change the crystal structure and the resistance to pitting (general engineering knowledge, not in our data). In our data, the lowest chromium minimum in each family is austenitic 16.0 wt% (Stainless steel 301); ferritic 10.500 wt% (Stainless steel 409); martensitic 11.5 wt% (Stainless steel 410); duplex 21.0 wt% (Lean duplex stainless steel 2101 (UNS S32101)); precipitation hardening 11.00 wt% (Custom 465 stainless steel).

What stainless steel composition data is missing?

Not found in any source we hold: a molybdenum limit for 17 of 37 grades, a nitrogen limit for 21, and printed limits (rather than nominal values) for Super duplex stainless steel 2507. Product-analysis tolerances, which let a mill certificate fall slightly outside a limit, are not in our data, and PREN is held for only 2 profiles.

Not on the page. No stainless steel profile is left out. Profiles added to these families later are picked up automatically when their chromium limit can be read.
Nominal values only. Super duplex stainless steel 2507 prints nominal values, not limits, for chromium, nickel, molybdenum and nitrogen, so it can only be "close" in the matcher.
Typical analyses are not limits. Super-austenitic stainless steel 904L also carries a typical analysis from a mill datasheet next to the specification range; it is shown, but the matcher does not treat it as a limit.
Elements without limits. 17 grades print no molybdenum limit, 21 no nitrogen limit and 4 no nickel limit; the cited source may simply not list them. Product-analysis tolerances and the allowed variation between heats are not in our data.
One source per grade. The tables show the limits of the main source; where the profile text names another source with different numbers, both are shown above. A purchase order's own standard governs.
PREN. Held for 2 profiles only. We do not compute it.
Condition of the strength records. Many strength records do not state temper or form. They are shown with whatever the source states.

Questions people ask

What is the composition of 316L stainless steel?

Stainless steel 316L (UNS S31603) is specified at 16.0 to 18.0 wt% chromium, 10.0 to 14.0 wt% nickel, 2.00 to 3.00 wt% molybdenum, at most 0.030 wt% carbon, at most 0.10 wt% nitrogen, at most 2.00 wt% manganese and at most 0.75 wt% silicon, with iron as the balance (per Combined Metals, nominal composition table). The low carbon limit separates it from Stainless steel 316 (UNS S31600), which prints at most 0.08 wt% carbon (per UPMET).

What is the composition of 430 stainless steel?

Stainless steel 430 (UNS S43000) is a ferritic grade specified at 16.0 to 18.0 wt% chromium, at most 0.12 wt% carbon, at most 0.75 wt% nickel, at most 1.00 wt% manganese and at most 1.00 wt% silicon, with iron as the balance (ASTM A240 limits as printed by ATI). Its record has at most 0.50 wt% molybdenum and no nitrogen limit.

What is the composition of duplex stainless steel?

Duplex stainless steel 2205 (UNS S32205) prints 22.0 to 23.0 wt% chromium, 4.5 to 6.5 wt% nickel and 0.14 to 0.20 wt% nitrogen (per ICAST); Lean duplex stainless steel 2304 (UNS S32304) prints 21.5 to 24.5 wt% chromium, 3.0 to 5.5 wt% nickel and 0.05 to 0.20 wt% nitrogen (per ICAST). Across the 4 duplex grades in our data, nickel limits run 1.35 to 7 wt% (the top value is a nominal one).

What is the difference between 304 and 316 stainless steel composition?

Stainless steel 316 (UNS S31600) adds molybdenum: it prints 2 to 3 wt% molybdenum (per UPMET), while Stainless steel 304 (UNS S30400) prints 17.5 to 20 wt% chromium and 8 to 11 wt% nickel and has no molybdenum limit in our record (per AZoM). The 316 chromium and nickel limits are 16 to 18 and 10 to 14 wt%.

Does stainless steel always contain nickel?

No. 33 of 37 grades print a nickel limit, and the ferritic family prints a nickel maximum of 1.00 wt% at most, for example at most 0.75 wt% nickel for Stainless steel 430 (per ATI). Austenitic grades print nickel 6.0 to 28 wt%.

How much chromium and nickel is in 18/8 stainless steel?

The name 18/8 means roughly 18 wt% chromium and 8 wt% nickel (general engineering knowledge, not in our data). In our data, Stainless steel 304 (UNS S30400) prints 17.5 to 20 wt% chromium and 8 to 11 wt% nickel (per AZoM), and Stainless steel 304L (UNS S30403) prints 18.0 to 20.0 wt% chromium and 8.0 to 12.0 wt% nickel (per ICAST).

Related on Space Mushroom

How this was made

Each grade is a profile in the Space Mushroom database, drafted by AI assistants from the cited pages, with a script that checks each value against its source; each profile page lists its sources. The element limits on this page are read from the composition record of each profile when the page is built, and the strength, density and expansion values come from the profile property blocks with their conditions. The phrases the text relies on are checked against the profiles at build time. A named reviewer has not yet signed this article. Download everything as one CSV file (CC BY 4.0).

Data checked 2 November 2026. Next review when a profile changes.

How to cite: Space Mushroom, "What is stainless steel made of? Composition of 30+ grades", https://spacemushroom.com/articles/composition-of-stainless-steel/, data checked 2 November 2026.