What is Stainless Steel?

Stainless steels are iron-based alloys containing a minimum of 10.5% Chromium with or without other alloying elements.

The term "STAINLESS" implies a resistance to staining, rusting, and pitting in the general normal environment.

Stainless Steels are technically known as "heat and corrosion resisting steels". That means they have in general a higher resistance to corrosion in some definite environment, as well have a higher resistance to scaling at high temperature. With specific restrictions in certain types, the stainless steels can be shaped and fabricated in conventional ways. They can be produced and used in the as-cast condition, shapes can be produced by powder-metallurgy techniques, cast ingots can be rolled or forged. The rolled product can be drawn, bent, extruded, or spun. Stainless Steel can be further shaped by machining, and it can be joined by soldering brazing, and welding. It can be used as an integral cladding on plain carbon or low-alloy steels.

Classification of Stainless Steels

Based on alloy contents, internal structure, magnetic or non magnetic properties, and other qualities, stainless steels can be broadly classified into under noted five categories.

1. Martensitic Stainless Steels Martensitic Stainless steel contain 11 to 18 % chromium along with carbon in specific percentage, making it hardenable by air cooling. These stainless steels are extensively used for cutlery, knives surgical instruments, industrial blades, chemical plant equipments, aerospace applications and other industrial components. In addition to chromium and carbon elements like nickel, molybdenum, vanadium, tungsten etc. are also added in some special purpose grades.

2. Ferritic Stainless Steels These stainless steels contain chromium in the range of 11 to 30% with no or very little nickel, are ferromagnetic in nature and generally not hardenable by heat treatment, provide good corrosion resistance and good formability at low cost, and are extensively used for many automotive components. Inferior weldability of these steel can be improved by alloying with titanium or columbium A 15430 is the general purpose stainless steel of this group.

3. Austenitic Stainless Steel These steels contain 16 to 30% chromium 6 to 20 % nickel and low carbon content, has excellent corrosion resistance, high ductility and toughness. Work hardening during cold working helps to get desired mechanical properties. These can not be hardened by heat treatment. In AISI 200 series steels, nickel is partially substituted by manganese and nitrogen is also added which helps in improvement of corrosion resistance, strength and stabilisation of austenitic structure. In some grades, copper is also added to improve cold forming and corrosion resisting properties.

Austenitic grades are most widely used stainless steels. 200 series grades are having higher strength than 300 series stainless steel.

4. Precipitation Hardening Stainless Steels These steels contain titanium, copper, niobium, aluminum, tantalum, phosphorous which precipitates during ageing or heat treatment and improve the mechanical properties of the alloy. Precipitation hardening steels are of three types viz, austenitic, semi austenitic and martensitic are corrosion and oxidation resistant and retain its strength at elevated temperature. These are mostly used in aerospace applications.

5. Duplex Stainless Steels In these steels structure is controlled in order to give equal ferrite and austenite to develop excellent corrosion resistance property to with stand chloride steels corrosion cracking. These steels exhibit higher yield strength than the austenitic grades and better resistance to chloride corrosion, of these properties makes it suitable for fabrication of various industrial equipments for typical corrosive environments, where austenitic or ferritic grades are generally found unsuitable.

Grades

Stainless Steel Grades

Grade C%(Max.) Si% Mn% P% S% Cr% Mo% Ni% Other% AISI 303 0.15 1.00 2.00 0.200 0.150 17.00/19.00 0.60(optional) 8.00/10.00 - AISI 304 0.08 1.00 2.00 0.045 0.030 18.00/20.00 - 8.00/10.50 - AISI 304L

0.030 1.00 2.00 0.045 0.030 18.00/20.00 - 8.00/12.00 -

AISI 310 0.25 1.50 2.00 0.045 0.030 24.00/26.00 - 19.00/22.00 - AISI 310S

0.08 1.50 2.00 0.045 0.030 24.00/26.00 - 19.00/22.00 -

AISI 316 0.08 1.00 2.00 0.045 0.030 16.00/18.00 2.00/3.00 10.00/14.00 - AISI 316L

0.030 1.00 2.00 0.045 0.030 16.00/18.00 2.00/3.00 10.00/14.00 -

AISI 316Ti

0.08 1.00 2.00 0.045 0.030 16.00/18.00 2.00/3.00 10.00/14.00 Ti=5xC%Min to Max 0.70%

AISI 321 0.08 1.00 2.00 0.045 0.030 17.00/19.00 - 9.00/12.00 Ti=5xC%Min to Max 0.70% AISI 347 0.08 1.00 2.00 0.040 0.030 17.00/19.00 - 9.00/13.00 Columbium + Tantalum 10xC% Min

to 1.10 Max) AISI 410 0.15 1.00 2.00 0.040 0.030 11.50/13.50 - - - AISI 416 0.15 1.00 1.25 0.060 0.150 12.00/14.00 0.60(optional) - - AISI 420 0.15 1.00 1.00 0.040 0.030 12.00/14.00 - - - AISI 430 0.12 1.00 1.00 0.040 0.030 16.00/18.00 - - - AISI 431 0.20 1.00 1.00 0.040 0.030 15.00/17.00 - 1.25/2.50 -

Alloy Steel Grades

Grade C%(Max.) Mn% P% S% Si% Cr% Mo% Ni% Other%

F-1(SA-182) 0.28 Max 0.60/0.90 0.045 0.045 0.15/0.35 - 0.44/0.65 - - F-2(SA-182) 0.05/0.21 0.30/0.80 0.040 0.040 0.10/0.60 0.50/0.81 0.44/0.65 - - F-5(SA-182) 0.15 Max 0.30/0.60 0.030 0.030 0.50 MAX. 4.00/6.00 0.44/0.65 0.50 MAX. -

F-5a (SA-182) 0.25 Max 0.60 Max 0.040 0.040 0.50 MAX. 4.00/6.00 0.44/0.65 0.50 MAX. - F-6a(SA-182) 0.15 Max 1.00 Max 0.040 0.030 1.00 MAX. 11.5/13.5 - 0.50 MAX. - F-9(SA-182) 0.15 Max 0.30/0.60 0.030 0.030 0.50/1.00 8.00/10.00 0.90/1.10 - -

F-11 class -I (SA-182) 0.05/0.15 0.30/0.60 0.030 0.030 0.50/1.00 1.00/1.50 0.44/0.65 - - F-11 class -2 (SA-182) 0.10/0.20 0.30/0.80 0.040 0.040 0.50/1.00 1.00/1.50 0.44/0.65 - - F-11 class 3 (SA-182) 0.10/0.20 0.30/0.80 0.040 0.040 0.50/1.00 1.00/1.50 0.44/0.65 - - F-12 class -I (SA-182) 0.05/0.15 0.30/0.60 0.045 0.045 0.50 MAX. 0.80/1.25 0.44/0.65 - - F-12 class-II (SA-182) 0.10/0.20 0.30/0.80 0.040 0.040 0.10/0.60 0.80/1.25 0.44/0.65 - - F-21 class -I (SA-182) 0.05/0.15 0.30/0.60 0.040 0.040 0.50 MAX. 2.65/3.35 0.80/1.06 - - F-22 class -I (SA-182) 0.05/0.15 02.30/0.60 0.040 0.040 0.50 MAX. 2.00/2.50 0.87/1.13 - V=0.30

Cb=0.20 LF2

(SA -350) 0.20/0.25 1.20/1.35 0.025 0.025 0.15/0.30 0.20 MAX. 0.80 MAX. 0.25 MAX. -

F-429 0.12 Max 1.00 Max 0.040 0.030 0.75 MAX. 14.00/16.00 - 0.50 MAX. -

F-430 0.12 Max 1.00 Max 0.040 0.030 0.75 MAX. 16.00/18.00 - 0.50 MAX. - EN-19 0.35/0.45 0.50/0.80 0.050 0.050 0.10/0.35 0.90/1.50 0.20/0.40 - - EN-24 0.35/0.45 0.45/0.70 0.050 0.050 0.10/0.35 0.90/1.40 0.20/0.35 1.30/1.80 - EN-353 0.20 MAX. 0.50/1.00 0.050 0.050 0.35 MAX. 0.75/1.25 0.80/0.15 1.00/1.50 - EN-354 0.20 MAX. 0.50/1.00 0.050 0.050 0.35 MAX. 0.75/1.30 0.10/0.20 1.50/2.00 -

20MM Cr5 0.17/0.22 1.10/1.40 0.035 0.035 0.15/0.35 1.00/1.30 - - - SAE8620 0.17/0.23 0.70/0.90 0.040 0.040 0.20/0.35 0.40/0.60 0.15/0.25 0.40/0.70 - EN-36A 0.15 Max 0.30/0.60 0.050 0.050 0.10/0.35 0.60/1.10 - 3.00/3.75 - EN-36B 0.15 Max 0.30/0.60 0.050 0.050 0.10/0.35 0.60/1.10 3.00/3.75 EN-36B 0.12/0.18 0.30/0.60 0.050 0.050 0.10/0.35 0.60/1.10 0.10/0.25 3.00/3.75

Precipitation Hardening Stainless Steels

(% Max.)

Type Trade Design C P S Si Mn Cr Ni Mo Other Austenitic

600 A-286 0.08 * * 0.40 1.40 15.00 26.00 1.30 V0.3,Ti2.0, Al 0.35,B 0.003

- 17-10P 0.12 0.25 0.030 0.60 0.75 17.00 10.00 * Semi-Austenitic

631 17-7PH 0.07 0.020 0.010 0.40 0.60 17.00 7.00 * Al 1.15 632 PH 15-7Mo 0.07 0.020 0.010 0.40 0.60 15.00 7.00 2.20 Al 1.15 633 AM-350 0.10 0.020 0.010 0.25 0.80 16.50 4.30 2.75 N 0.10 634 Am-355 0.13 0.020 0.010 0.25 0.95 15.5 4.30 2.75 N 0.10

Martensitic 630 17-4PH 0.04 0.020 0.010 0.60 0.25 16.0 4.00 * cu 3.2, cb+Ta 0.25 635 Stainless W 0.07 * * 0.50 0.50 16.5 6.75 * Al 0.40, Ti 0.8

Duplex Stainless Steel

Type C P S Si Mn Cr Ni Mo N Cu % Ferrite 329 0.08 0.045 0.03 1.00 2.0 26.00 5.00 1.0/2.0 - - 60-70

Ferralium-225 (Cobot corpn.) 0.08 0.04 0.04 2.00 2.00 24.0/27.0 4.5/6.5 2.0/4.00 0.1

(Min.) 1.3/4.0 50 3 RE-60 0.03 0.03 0.03 1.7 1.5 18.5 4.7 2.7 50

U-50 (Creusot Lorie) 0.03 0.04 0.03 1.0 2.00 20.0/22.0 5.5/8.5 2.0/3.0 0.2 0.5 30-50

Mechanical Properties

MARTENSITIC STAINLESS STEEL

Grade Tensile Strength Ksi Mpa

Yield Strength(02 % offset) Ksi Mpa

Elongation in 2" (50.80mm)

% Hardness

(Rockwell) Product

Form

403 70 483 45 310 25 B80 410 70 483 45 310 25 B80 414 120 827 105 724 15 B98 416 75 517 40 276 30 B82 (Bar)

416 Sc 75 517 40 276 30 B82 (Bar) 420 95 655 50 345 25 B92 (Bar)

420 F 95 655 55 379 22 220 (Brinell) (Bar) 422 145 1000 125 862 18 320 (Brinell) (Bar) 431 125 862 95 655 20 C24 (Bar)

440 A 105 724 60 414 20 B95 (Bar) 440 B 107 738 62 427 18 B96 (Bar) 440 C 110 758 65 448 14 B97 (Bar)

FERRITIC STAINLESS STEELS

Grade Tensile Strength Ksi Mpa

Yield Strength (02 % offset)

Ksi Mpa Elongation in 2"

(50.80mm) %

Hardness (Rockwell)

Product Form

405 65 448 40 276 25 B75 409 65 448 35 241 20 B75 429 70 483 40 276 30 B80 (Plate) 430 75 517 50 345 25 B85

430 F 95 655 85 586 10 B92 430 F Se 95 655 85 586 10 B92 (Wire)

434 77 531 53 365 23 B83 436 77 531 53 365 23 B83 442 80 552 45 310 20 B90 (Bar) 446 80 552 50 345 20 B83

AUSTENITIC STAINLESS STEEL

Grade Tensile Strength Ksi Mpa

Yield Strength (02 % offset)

Ksi Mpa Elongation in 2"

(50.80mm) %

Hardness (Rockwell)

Product Form

201 95 655 45 310 40 B90 202 90 612 45 310 40 B90 205 120.5 831 69 476 58 B98 (Plate) 301 110 758 40 276 60 B85 302 90 612 40 276 50 B85

302 B 95 655 40 276 55 B85 303 90 621 35 241 50 (Bar)

303 Se 90 621 35 241 50 (Bar) 304 84 579 42 290 55 B80

304 L 81 558 39 269 55 B79 S30430 73 503 31 214 70 B70 304 N 90 621 48 331 50 B85 305 85 586 38 262 50 B80 308 115 793 80 552 40 (Wire) 309 90 621 45 310 45 B85

309 S 90 621 45 310 45 B85 310 95 655 45 310 45 B85

310 S 95 655 45 310 45 B85 314 100 689 50 345 40 B85 316 84 579 42 290 50 B79

316 F 85 586 38 262 60 B85 316 L 81 558 42 290 50 B79 316 N 90 621 48 331 48 B85 317 90 621 40 276 45 B85

317 L 86 593 38 262 55 B85 321 90 621 35 241 45 B80 329 105 724 80 552 25 230

(Brinell) (Strip)

330 80 552 38 262 40 B80 347 95 655 40 276 45 B85 348 95 655 40 276 45 B85 384 75 517 35 241 55 B70 (Wire)

PRECIPITATION HARDENING STAINLESS STEELS

Yield Strength (0.2% offset) Tensile Strength Type Condition

ksi Mpa Ksi Mpa Elongation Hardness Rockwell

600 Aged 720 C 100 690 145 1000 24 C 29 17.10P Aged 705 C 98 676 144 993 20 C 32 630 Aged 480 C 185 1275 200 1380 14 C 44 631 Aged 565 C 190 1310 205 1415 9 C 13 632 Aged 565 C 205 1415 215 1480 7 C 44 633 CR Tempered 190 1310 210 1450 10 - 634 CR Tempered 210 1450 230 1585 12 - 635 Aged 510 C 170 1170 190 1310 8 C 50 DUPLEX STEEL Type Yield Strength

Ksi Mpa Tensile Strength Ksi Mpa Elongation

329 80 550 105 724 25 Ferralium-25.5 70 480 107 740 20 3 RE-60 65 450 102-131 700-900 30 U-50 46-64 315-440 86-116 590-80 20-25

Equivalent Grades

EQUIVALENT SPECIFICATIONS OF VARIOUS COUNTRIES AISI USA

IS India

DIN Germany

AFNOR France

JIS Japan

BS Britain

SIS Sweden

UNS UNI Italy

301 10 Cr 17 Ni 7 1.4310 Z 12 CN 17-08 SUS 301 301 S 21 142331 S 30100 X 12 Cr Ni 1707 304 04 Cr 18 Ni 10 1.4301 Z 6 CN 18-09 SUS 304 304 S 15 142333 S 30400 X 5 Cr Ni 1810

304 L 02 Cr 18 Ni 11 1.4306 Z 2 CN 18-10 SUS 304 L 304 S 11 142352 S 30403 X 2 Cr Ni 1811 310 S 1.4845 SUS 310 S 142361 S 31008 X 6 Cr Ni 2520 316 04 Cr 17 Ni 12 Mo 1.4401

1.4436

Z 6 CND 17-11 SUS 316 316 S 31 142347

142343

S 31600 X 8 Cr Ni Mo 1713

1713

316 L 02 Cr 17 Ni 12 Mo 2 1.4404

1.4435

Z 2 CND 17-12

Z 2 CND 17-13

SUS 316 L 316 S 11 142348

142353

S 31603 X 2 Cr Ni Mo 1712

X 2 Cr Ni Mo 1713

321 04 Cr 18 Ni 10 Ti 20 321 Z 6 CNT 18-12 SUS 321 321 S 31 142337 S 32100 X 6 Cr Ni Ti 1811 409 1.4512 Z 5 CT 12 SUS 409 409 S 17 S 40900

410 S 430 05 Cr 17 1.4016 Z 8 C 17 SUS 430 430 S 17 142320 S 43000 X 2 Cr 17 17C