The technological process  of C70S6BY  steel  for automobile  engine  connecting rod is  130 t BOF-LF-RH- CCM-Heating-Rolling.   The content   of   S   and   N   in   steel(0.064%～0.068%Sand   136×10

-6

～142×10

-6

N) can   be   accurately  controlled  by  using1.5~2.0  low  basicity  CaO-SiO

2

-Al

2

O

3

-MgO  slag  system  in  LF  refine

nitrogen  driving  in  RH and for 5～10 min circulation after pump withdrawal. The microstructure of the steel is pearlite and a small amount of fer- rite by slow cooling in pit after rolling

the non-metallic inclusions in the steel are mainly MnS and composite inclusions.Of 1050℃  30  min  air  coling   steel

the  tensile   strength  is 995~1018  MPa

the  yield   strength  is   586~611  MPa

the  elongation   is   11.5%～13.0%

the   reducti

on   of  area   is   22%~24%

and   the   HB  brinell   hardness   number   is   285~301. All   indexes meet the requirements of breaking connecting rod.