Non-heat treated steel for connecting rod and connecting rod formed of same

Abstract

A non-heat treated steel for hot forging and for a connecting rod, containing, in mass percent: 0.3 to 0.8% of C; 0.1 to 2.0% of Si; 0.5 to 1.5% of Mn; 0.01 to 0.15% of P; 1.0% or less of Cr; 0.4% or less of V; 0.05% or less of Al; 0.005 to 0.03% of N; and the balance Fe and inevitable impurities. The non-heat treated steel has a value E of not larger than 150, the value E being calculated from the following equation: E =2804−1549× Ceq −8862× P −23.4× H where H is a value of a Rockwell hardness of the connecting rod made of the non-heat treated steel; P is a phosphorus content (%) in the connecting rod; and Ceq is a value of a carbon equivalent.

1 . A non-heat treated steel for hot forging and for a connecting rod, comprising, in mass percent: 
 0.3 to 0.8% of C;    0.1 to 2.0% of Si;    0.5 to 1.5% of Mn;    0.01 to 0.15% of P;    1.0% or less of Cr;    0.4% or less of V;    0.05% or less of Al;    0.005 to 0.03% of N; and    the balance Fe and inevitable impurities,    wherein the non-heat treated steel has a value E of not larger than 150, the value E being calculated from the following equation:        E= 2804−1549 ×Ceq− 8862 ×P− 23.4 ×H      where H is a value of a Rockwell hardness (C-scale) of the connecting rod made of the non-heat treated steel; P is a phosphorus content (%) in the connecting rod; and Ceq is a value of a carbon equivalent, the value Ceq being calculated from the following equation:        Ceq =C(%)+0.166Si(%)+0.22Mn(%)+0.25Cr(%)+1.8V(%).    
   
   
       2 . A non-heat treated steel as claimed in  claim 1 , further comprising at least one selected from the group consisting of 0.03 to 0.15% of S, 0.3% or less of Pb and 0.01% or less of Ca.  
   
   
       3 . A connecting rod comprising, in mass percent: 
 0.3 to 0.8% of C;    0.1 to 2.0% of Si;    0.5 to 1.5% of Mn;    0.01 to 0.15% of P;    1.0% or less of Cr;    0.4% or less of V;    0.05% or less of Al;    0.005 to 0.03% of N; and    the balance Fe and inevitable impurities,    wherein the connecting rod has a value E of not larger than 150, the value E being calculated from the following equation:        E= 2804−1549 ×Ceq− 8862 ×P− 23.4 ×H      where H is a value of a Rockwell hardness (C-scale) of the connecting rod; P is a phosphorus content (%) in the connecting rod; and Ceq is a value of a carbon equivalent, the value Ceq being calculated from the following equation:        Ceq =C(%)+0.166Si(%)+0.22Mn(%)+0.25Cr(%)+1.8V(%).    
   
   
       4 . A connecting rod as claimed in  claim 3 , further comprising at least one selected from the group consisting of 0.03 to 0.15% of S, 0.3% or less of Pb and 0.01% or less of Ca.  
   
   
       5 . A connecting rod as claimed in  claim 3 , wherein the connecting rod has a Rockwell hardness (C-scale) of from 24 to 35.