Japanese Automobile Standards
Carbon Steels and Boron Steels
Chemical Composition, %
No. Steel
Grade		 C Si Mn P S B Cu Ni Cr Ni + Cr
1 S 10 C .08/.13 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
2 S 12 C .10/.15 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
3 S 15 C .13/.18 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
4 S 17 C .15/.20 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
5 S 20 C .18/.23 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
6 S 22 C .20/.25 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
7 S 25 C .22/.28 .15/.35 .30/.60 .030 max .035 max — .30 max .20 max .20 max .35 max
8 S 28 C .25/.31 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
9 S 30 C .27/.33 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
10 S 33 C .30/.36 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
11 S 35 C .32/.38 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
12 S 38 C .35/.41 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
13 S 40 C .37/.43 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
14 S 43 C .40/.46 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
15 S 45 C .42/.48 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
16 S 48 C .45/.51 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
17 S 50 C .47/.53 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
18 S 53 C .50/.56 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
19 S 55 C .52/.58 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
20 S 58 C .55/.61 .15/.35 .60/.90 .030 max .035 max — .30 max .20 max .20 max .35 max
21 ASBo 20 .18/.23 .15/.35 .30/.60 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
22 ASBo 25 .22/.28 .15/.35 .30/.60 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
23 ASBo 28 .25/.31 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
24 ASBo 30 .27/.33 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
25 ASBo 33 .30/.36 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
26 ASBo 35 .32/.38 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
27 ASBo 38 .35/.41 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
28 ASBo 40 .37/.43 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
29 ASBo 43 .40/.46 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
30 ASBo 45 .42/.48 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
31 ASBo 48 .45/.51 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
32 ASBo 50 .47/.53 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max
33 ASBo 53 .50/.56 .15/.35 .60/.90 .030 max .035 max .0005 min .30 max .20 max .20 max .35 max

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