20号工字钢规格有两种

20a号工字钢规格:h=200mm,b=100mm,d=7mm,t=11.4mm,t=9mm,r1=4.5mm

20b号工字钢规格:h=200mm,b=102mm,d=9mm,t=11.4mm,t=9mm,r1=4.5mm