?????????????3.6?4.6?4.8?5.6?6.8?8.8?9.8?10.9?12.9?10???????8.8???????????????????????(?????)???????????????????????????????????????????????????????????48??4.8?

???????4.8??????????

1????????????400MPa?;

2???????????0.8;

3?????????????400×0.8=320MPa

????10.9?????????????????????

1????????????1000MPa?;

2???????????0.9;

3?????????????1000×0.9=900MPa?

?????????????????????????????????????????????????????????????

??????8.8??10.9??????????????8.8GPa?10.9GPa 8.8 ??????800N/MM2 ??????640N/MM2 ???????"X.Y"??????X*100=?????????X*100*(Y/10)=????????(????????????/????=Y/10??0.Y????) ?4.8? ???????????400MPa;??????400*8/10=320MPa????????????A4-70?A2-70??????????????????????????????????????????(m)???(cm)???(mm)??????????????????????????????????????(inch)?????????????????1??????(10??) 1m =100 cm=1000 mm2??????(8??) 1??=8?? 1??=25.4 mm 3/8??×25.4 =9.523?1/4???????????????????? 4#? 5#? 6#? 7#? 8#?10#?12#?