??????????????????????
????
?????????????MPa 345-305 ????????????bMPa 510-490???????5%??21??
Q345QC???????????Q345QC??????
??????
??????????????????????????????????????е?????????????
???????????????????????
??????????????????????????????????????????????????????????????????????????????????????????????г?????????????Ρ??磬?????????????????????????????????????????????λ??????ò??????д?????б????????淶?????????????????????????????г?????ɡ????????????????????????????????????????Ч????????????
??????????????????????
10??2000??8000+ 70??
10??2000??8000+ 76??
10??2000??8000+ 70??
4??1500??8000+ 21??
10??2000??8000+ 70??
4??1500??800035??
4??1500??8000+ 80??
8??1800??8000+ 70??
6??1800??8000+ 80??
???????????????лл ?? ????? ????:???????????????
?????????76??????????????????????