Stainless Steels

 

Stainless steels are iron alloys with a minimum of 10.5% chromium. Other alloying elements are added to enhance their structure and properties such as formability, strength and cryogenic toughness. These include metals such as:

  • Nickel

  • Molybdenum

  • Titanium

  • Copper

Non-metal additions are also made, the main ones being:

  • Carbon
  • Nitrogen

Stainless steel does not readily corrode, rust or stain with water as ordinary steel does, but despite the name it is not fully stain-proof, most notably under low oxygen, high salinity, or poor circulation environments.  There are different grades and surface finishes of stainless steel to suit the environment the alloy must endure. Stainless steel is used where both the properties of steel and resistance to corrosion are required.

Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film (the rust) is active and accelerates corrosion by forming more iron oxide, and due to the greater volume of the iron oxide this tends to flake and fall away. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal's internal structure, and due to the similar size of the steel and oxide ions they bond very strongly and remain attached to the surface.

 

Stainless Steel - Comparison of Grade Specifications

 

 
 

Grade

UNS No

Old British

Euronorm

Swedish SS

Japanese JIS

BS

En

No

Name

301

302

303

303Se

304

304L

304H

304N

(302HQ)

305

309S

310

310S

314

316

316L

316H

316N

316Ti

317L

321

329

347

403

405

409

410

416

416Se

420

420F

430

430F

431

434

440C

444

630

631

(904L)

(2111HTR)

(2205)

(2304)

(2507)

(4565S)

(Zeron100)

(UR52N+)

S30100

S30200

S30300

S30323

S30400

S30403

S30409

S30451

S30430

S30500

S30908

S31000

S31008

S31400

S31600

S31603

S31609

S31651

S31635

S31703

S32100

S32900

S34700

S40300

S40500

S40900

S41000

S41600

S41623

S42000

S42020

S43000

S43020

S43100

S43400

S44004

S44400

S17400

S17700

N08904

S30815

S31803

S32304

S32750

S34565

S32760

S32520

301S21

302S25

303S31

303S42

304S31

304S11

-

-

394S17

305S19

309S24

310S24

310S16

-

316S31

316S11

316S51

-

320S31

317S12

321S31

-

347S31

403S17

405S17

409S19

410S21

416S21

416S41

420S37

416S29

430S17

-

431S29

434S17

-

-

-

460S52

904S13

-

318S13

-

-

-

-

-

-

58A

58M

-

58E

-

-

-

-

-

-

-

-

-

58H,58J

-

-

-

-

-

58B,58C

-

58G

-

-

-

56A

56AM

-

56C

-

60

-

57

-

-

-

-

-

-

-

-

-

-

-

-

-

1.4310

1.4319

1.4305

-

1.4301

1.4306

1.4948

-

1.4567

1.4312

1.4833

1.4840

1.4845

1.4841

1.4401

1.4404

1.4919

1.4406

1.4571

1.4438

1.4541

1.4460

1.4550

1.4000

1.4002

1.4512

1.4006

1.4005

-

1.4021

-

1.4016

1.4104

1.4057

1.4113

1.4125

1.4521

1.4542

1.4568

1.4539

1.4835

1.4462

1.4362

1.4410

1.4565

1.4501

1.4507

X10CrNi18-8

-

X8CrNiS18-9

-

X5CrNi18-10

X2CrNi18-11

X6CrNi18-11

-

X3CrNiCu18-9-4

-

X12CrNi23-13

X15CrNi25-20

X8CrNi25-21

X15CrNiSi25-21

X5CrNiMo17-12-2

X2CrNiMo17-12-2

-

X2CrNiMoN17-11-2

X10CrNiMoTi18-10

X2CrNiMo18-16

X6CrNiTi18-10

X8CrNiMo27-5

X6CrNiNb18-10

X7Cr13

X7CrAl13

X6CrTi12

X12Cr13

X12CrS13

-

X20Cr13

-

X8Cr17

X12CrMoS17

X17CrNi16-2

X6CrMo17-1

X105CrMo17

X1CrMoTi18-2

X5CrNiCuNb16-4

X7CrNiAl17-7

X1NiCrMoCuN25-20-5

X9CrNiSiNCe21-11-2

X2CrNiMoN22-5-3

X2CrNiN23-4

X2CrNiMoN25-7-4

X2CrNiMnMoN24-17-6-4

X2CrNiMoCuWN25-7-4

X2CrNiMoCuN25-6-3

2331

-

2346

-

2332

2352

-

2371

-

-

-

-

2361

-

2347

2348

-

2375

2350

2367

2337

2324

2338

2301

-

-

2302

2380

-

2303

-

2320

2383

2321

2325

-

2326

-

2388

2562

2368

2377

2327

2328

-

-

-

SUS 301

SUS 302

SUS 303

SUS 303Se

SUS 304

SUS 304L

-

SUS 304N1

SUS XM7

SUS 305

SUS 309S

SUH 310

SUS 310S

-

SUS 316

SUS 316L

-

SUS 316N

SUS 316Ti

SUS 317L

SUS 321

SUS 329J1

SUS 347

SUS 403

SUS 405

SUH 409

SUS 410

SUS 416

-

SUS 420J1

SUS 420F

SUS 430

SUS 430F

SUS 431

SUS 434

SUS 440C

SUS 444

SUS 630

SUS 631

-

-

SUS 329J3L

-

-

-

-

-

 

 Stainless Steel Properties

Precipitation Hardening Stainless

The main characteristics of precipitation hardening stainless specifications are the combination of the corrosion resistance of an austenitic stainless with the hardenability of a martensitic stainless.

ASTMWerkstoffDINFirth Vickers
  • A564 Grade 630
  • 1.4542
  • X5CrNiMoCuNb145PH
  • 1.4594
   
     

High Alloyed Austenitic Stainless

High contents of chromium, nickel, molybdenum and nitrogen give high alloyed austenitic stainless steel grades different characteristics to those of standard austenitic specifications. 904L has similar mechanical properties to the more common austenitic grades but has superior resistance to uniform corrosion. UNS S31254 provides exceptionally good resistance to uniform corrosion combined with higher strength and mechanical properties than the more common austenitic grades

UNSAISIWerkstoffOutokumpuASTM
  • 1.4547
  • 254SMO
  • A276
  • N08904
 
  •  1.4539
  •  6Mo (Moly)
  • A479
   
  • EN10272
 
  • B677
       
  • F44

Austenitic Stainless

With the average chromium content of 18% and nickel content of 8% austenitic stainless steels are sometimes referred to as 18/8 (although the actual chromium and nickel content can vary from these figures). Austenitic stainless steels are non magnetic and cannot be hardened by heat treatment, though they can strain harden rapidly when cold worked.

BS970AISIWerkstoffDINUNS
  • 316S11
  • 1.4845
  • X5CrNi18-10
  •  S31000
  • 316S15
  • 1.4541
  • X5CrNi 18-10
  •  S31008
  • 310S24
  • 316
  • 1.4571
  • X8CrNiS18-9
  •  S32100
  • 321S31
  • 316Ti
  • 1.4301
  • X8CrNiS18-9
  •  S30400
  • 304S31
  • 321
  • 1.4305
  • X2CrNi 19-11
  •  S30300
  • 304S15
  • 304
  • 1.4306
  • X6CrNiTi 18-10
  •  S30403
  • 303S21
  • 304L
  • 1.4307
  • X12CrNi 25-21
  •  S30100
  • 304S11
  • 303
  • 1.4310
  • X6CrNiMoTi 17-12-2
  •  S31600
  • EN58E
  • 1.4539
 
  •  S31603
  • EN58AM
 
  • 1.4404
 
  •  S31635
  • EN58M
       
  • EN58E
       
  • EN58B
       
         

Martensitic Stainless

Heat treated martensitic stainless steel grades offer high strength and hardness. Martensitic grades can be heat treated due to having higher carbon content than other types of stainless steel. Martensitic grades are less ductile than other types of stainless steel. These grades are magnetic and are best suited for applications which require good corrosion resistance with good mechanical properties.

 

BS970AISIWerkstoffDINUNS
  • 416S21
  • 1.4112
  • X12CrS13
  • S41000
  • 410S21
  • 1.4125
  • X12Cr13
  • S42000
  • 420S29
  • 1.4057
  • X20Cr13
  • S43100
  • 420S37
  • 1.4005
  • X30Cr13
  • S44003
  • 420S45
  • 1.4006
  • X17CrNi16-2
  • S44004
  • 431S29
  • 1.4021
  • X90CrMoV18
 
  • EN56AM
 
  • 1.4208
  • X105CrMo17
 
  • EN56A
       
  • EN56C
       
  • EN56D
       
  • EN57
       

Duplex & Super Duplex Stainless

Duplex and Super Duplex stainless steel grades offer resistance to stress corrosion and crevice corrosion. They are higher strength grades than standard austenitic stainless steel specifications.

UNSASTMWerkstoff
  • A182
  •  1.4462
  • F51
  • 1.4501
 
  • F55
  • EN10083

Heat Treatment

Heat treatment is only suitable for specific grades of stainless. When heat treating a stainless the hardening temperatures, including rate of heating, cooling and soaking times will vary due to factors such as the shape and size of each  component. Other considerations during the heat treatment process include the type of furnace, quenching medium and work piece transfer facilities. Please consult your heat treatment provider for full guidance on heat treatment of stainless steel grades.