(1) Hardened stainless steel

This type of stainless steel is made up of steel that can be hardened by heat treatment in the 400 series. Among them, the free-cutting steels are: Y12Cr13 (416), Y30Cr13 (420F) and Y108Cr17 (440F); the cutting performance is generally 12Cr12 ( 403), 12 Cr13 ( 410 ), 20Cr13 (420), 17Cr16Ni2 ( 431 ), 68Cr17 (440A), 85Cr17 (440B) and 108Cr17 (440C). All of the above steels are martensitic steels and are therefore magnetic in the annealed state; they can be quenched and tempered to various grades. The most easily cut of this type of steel is Y12Cr13 (416), and the most difficult to machine is 108Cr17 (440C), because the high carbon content of 108Cr17 (440C) steel will cause severe wear of cutting tools.

(2) Non-hardened stainless steel

This type of steel large-diameter thick-walled pipe includes those steels in the 400 series that are unlikely to be significantly hardened by heat treatment. These steels are made of ferrite and are therefore magnetic in the annealed state. Among them, YlOCr17 (430F) is easy to cut; the cutting performance is generally 06Cr13A1 (405), IOCr12 (430) and 16Cr25N (4; 46).

(3) Austenitic stainless steel

This type of steel is the so-called chromium-nickel 300 series steel. Their range has recently expanded to include several Cr-Ni-Mn steels in the 200 series. The structure of this type of steel in an annealed state is austenite and thus is substantially non-magnetic, and it is impossible to achieve hardening by heat treatment. Large-diameter thick-walled pipes However, most of these steels have a high work hardening rate, which is, of course, much higher than that of ferritic and martensitic stainless steels.

Among these steels, Y12Cr18N19 (303) and Y12Cr18N19Se (303Se) are easily cut. In addition, some standard austenitic stainless steels are also included, such as 12Cr17Mn6N15N (201), 12Cr18Mn9Ni5N (202), 12Cr17N17 (301), 12Cr18N19 (302), 06Cr19Nil0 (304), lOCr18Ni12 (305), 06Cr20Nill (308), 16Cr23N113 ( 309), 20Cr25N120 (310), 06Cr17Ni12M02 (316), 06Cr19N113M03 (317), 06Cr18NillTl (321), 06Cr18NillNb (347), etc., and many other austenitic steels not listed in the national standard.