Material Selection – Types of stainless steel
Austenitic – A family of alloys containing chromium and nickel (and manganese and nitrogen when nickel levels are reduced), generally built around the type 302 chemistry of 18% Cr, 8% Ni, and balance mostly Fe. These alloys are not hardenable by heat treatment.
Ferritic – This group of alloys generally containing only chromium, with the balance mostly Fe, are based upon the type 430 composition of 17% Cr. These alloys are somewhat less
ductile than the austenitic types and again are not hardenable by heat treatment.
Martensitic – The members of this family of stainless steels may be hardened and tempered just like alloy steels. Their basic building block is type 410 which consists of 12% Cr, 0.12% C, and balance mostly Fe.
Precipitation-Hardening – These alloys generally contain Cr and less than 8% Ni, with other elements in small amounts. As the name implies, they are hardenable by heat treatment.
Duplex – This is a stainless steel alloy group, or family, with two distinct microstructure phases — ferrite and austenite. The Duplex alloys have greater resistance to chloride stress
corrosion cracking and higher strength than the other austenitic or ferritic grades.
Cast – The cast stainless steels, in general, are similar to the equivalent wrought alloys. Most of the cast alloys are direct derivatives of one of the wrought grades, as C-8 is the cast equivalent of wrought type 304. The C preceding a designation means that the alloy is primarily used for resistance to liquid corrosion. An H designation indicates high temperature applications.
| Family of Stainless Steels | ||||||
| Alloy Group | Common Grades | |||||
| Austenitic | UNS No. | S30100 | S30400 | S3403 | S31600 | S31603 |
| Commonly | 301 | 304 | 304L | 316 | 316L | |
| UNS No. | S32100 | S31000 | S30815 | N08904 | S31254 | |
| Commonly | 321 | 310 | 253MATM or 2111HTRTM |
904L | 254SMOé | |
| Ferritic | UNS No. | S40900 | S43000 | * | S44400 | S44600 |
| Commonly | 409 | 430 | DIN 1.4003 3CR12TM or 5CR12TM |
444 | 446 | |
| Martensitic | UNS No. | S41000 | S42000 | S43100 | S44004 | |
| Commonly | 410 | 420 | 431 | 440C | ||
| Duplex | UNS No. | S32304 | S31803 | S32750 | S32550 | S32760 |
| Commonly | 2304 | 2205 | 2507 | Ferrallium 255TM |
Zeron 100TM | |
| Precipitation Hardening |
UNS No. | S17400 | S17700 | S15500 | ||
| Commonly | 17-4PH or 630 |
17-7PH or 631 |
15-5PH | |||
| * UNS No. not yet allocated | ||||||
Reference: http://www.fanagalo.co.za
