Japan’s standard of steel grading basically take the America’s standard of AISI, but prefixed with SUS, which represents stainless steel, and SUH, heat resistant steel, the letters are explained as follows:
- The first letter S means Steel
- The Second letter U is Use, meaning Special Use
- The last letter S means Stainless, while H means Heat resistant
Numbers after SUS follow the standard of AISI.
In addition, to distinguish steel types, it is suffixed with English letters, they are:
- B: Bar, means bar steel
- HP：Hot Plate, means hot rolled plate steel
- CP: Cold Plate, means cold polled plate steel
- HS: Hot Strip, means hot rolled strip steel
- CS: Cold Strip, means cold rolled strip steel
- WR: Wire, means steel wire
- TP: Tube Pipes, means steel pipes for pipelines
- TB: Boiler Heat Exchange Tube, means steel pipes for heat exchanging
- L: Low Carbon, means low carbon content
- N: Nitrogen, means nitrogen is added
- J: Japan, means unique grading of Japan
German expression of stainless steel grade
Low-alloy Steel
A steel grade of Low-alloy Steel begins with the number which represents average carbon content by ten thousandth, followed by the alloying element symbols and the specified values calculated from their content. The alloying element symbols should be arranged by their content, or in alphabetical order if they have the same average percentages.
Please refer to the following list for the divisor of alloying element symbols (rounded to whole numbers).
The divisor of alloying element symbols（the multiplier of average%）
Cr、Co、Mn、Ni、Si、W：4
Al、Cu、Mo、Nb、Ta、Ti、V：10
C、N、P、S：100
Such as:
15Cr3—Chromium steel with 0.15%C、(3/4)%Cr (=0.75%)
24CrMoV5-5—Chromium-molybdenum-vanadium steel with 0.24%C、(5/4)%CR(=1.25%)、(5/10)%Mo(=0.50%)
High-alloy Steel
A steel grade of High-alloy Steel begins with a letter X, followed by the number which represents average carbon content by ten thousandth, and then the alloying element symbols arranged by their content; lastly average percentage of alloying elements contents (rounded to whole numbers).Please refer to the following example.
X1OCrNi18-8——Stainless steel with 0.10%C, 18%Cr, 8%Ni.
X1OCrNi18-8——0.10％C、18％Cr、8％Ni
British (BS) expression of stainless steel grade
The main feature of the steel grade is the fourth letter S. The first number, and the second and third number before the letter represents steel type and series, and a partial of grades are basically the same with the American AISI stainless steel series. The major part of grades are:
3××S××
represents austenite stainless steel (including nickel-chromium steel series, nickel-chromium-molybdenum steel series, and etc.)
4××S××
represents martensite steel and ferritic stainless steel.
A few steel grades are:
2××S××
represents chromium-manganese-nickel-nitrogen austenitic stainless steel with chromium added, which is set to be distinguished with 3××S×× series and the free-cutting series 2××M××.
Numbers after the letter S, the fifth and sixth number distinguishes individuals in a steel group with the same basic composition, and it is numbered with reference of carbon content and changes of other compositions.Steel examples are as follows:
BS 304 S 12——18-8 austenitic stainless steel with C≤0.03%, SiO.20～1.00%, MnO.50～2.00%, Cr17.50～19.00%, Ni9.00～12.00%;
it is similar to American AISI 304L steel.
BS 304 S 15——with C≤0.06%, Si8.00～11.00%,
while the other compositions are the same with 304 S12 steel, similar to American AISI304 steel.
BS 403 S 17——Cr13 ferritic stainless steel with C≤0.08%, Si≤0.08%, Mn≤1.00%, Cr12.00～14.00%;
similar to American AISI403 steel.
