Steel For Mechanical Parts, Method For Producing Mechanical Parts From Said Steel And The Thus Obtainable Mechanical Parts

Abstract

Steel for mechanical components, wherein the composition thereof is, in percentages by weight: 0.19%≦C≦0.25%; 1.1%≦Mn≦1.5%; 0.8%≦Si≦1.2%; 0.01%≦S≦0.09%; trace levels≦P≦0.025%; trace levels≦Ni≦0.25%; 1%≦Cr≦1.4%; 0.10%≦Mo≦0.25%; trace levels≦Cu≦0.30%; 0.010%≦Al≦0.045%; 0.010%≦Nb≦0.045%; 0.0130%≦N≦0.0300%; optionally trace levels≦Bi≦0.10% and/or trace levels≦Pb≦0.12% and/or trace levels≦Te≦0.015% and/or trace levels≦Se≦0.030% and/or trace levels≦Ca≦0.0050%; the balance being iron and impurities resulting from the production operation, the chemical composition being adjusted so that the mean values J 3m , J 11m , J 15m and J 25m for five Jominy tests are such that: α=| J 11m −J 3m ×14/22− J 25m ×8/22|≦2.5 HRC; and β= J 3m −J 15m ≦9 HRC. Method for producing a mechanical component using this steel and a mechanical component produced in this manner.

1 . Steel for mechanical components, wherein the composition thereof is, in percentages by weight: 
 0.19%≦C≦0.25%;    1.1%≦Mn≦1.5%;    0.8%≦Si≦1.2%;    0.01%≦S≦0.09%;    trace levels≦P≦0.025%;    trace levels≦Ni≦0.25%;    1%≦Cr≦1.4%;    0.10%≦Mo≦0.25%;    trace levels≦Cu≦0.30%;    0.010%≦Al≦0.045%;    0.010%≦Nb≦0.045%;    0.0130%≦N≦0.0300%;    optionally trace levels≦Bi≦0.10% and/or trace levels≦Pb≦0.12%    and/or trace levels≦Te≦0.015% and/or trace levels≦Se≦0.030% and/or trace levels≦Ca≦0.0050%;    the balance being iron and impurities resulting from the production operation, the chemical composition being adjusted so that the mean values J 3m , J 11m , J 15m  and J 25m  for five Jominy tests are such that:      α=| J   11m   −J   3m ×14/22− J   25m ×8/22|≦2.5 HRC; and  β= J   3m   −J   15m ≦9 HRC.    
   
   
       2 . Steel for mechanical components according to  claim 1 , wherein the composition thereof is adjusted so that  
       β= J   3m   −J   15m ≦8 HRC.  
   
   
       3 . Steel for mechanical components according to  claim 1 , wherein the composition thereof is: 
 0.19%≦C≦0.25%;    1.2%≦Mn≦1.5%;    0.85%≦Si≦1.2%;    0.01%≦S≦0.09%;    trace levels≦P≦0.025%;    0.08%≦Ni≦0.25%;    1.1%≦Cr≦1.4%;    0.10%≦Mo≦0.25%;    0.06%≦Cu≦0.30%;    0.010%≦Al≦0.045%;    0.015%≦Nb≦0.045%;    0.0130%≦N≦0.0300%;    optionally trace levels≦Bi≦0.07% and/or trace levels≦Pb≦0.12% and/or trace levels≦Te≦0.010% and/or trace levels≦Se≦0.020% and/or trace levels≦Ca≦0.045%, the balance being iron and impurities resulting from the production operation.    
   
   
       4 . Steel for mechanical components according to  claim 3 , wherein the composition thereof is: 
 0.20%≦C≦0.25%;    1.21%≦Mn≦1.45%;    0.85%≦Si≦1.10%;    0.01%≦S≦0.08%;    trace levels≦P≦0.020%;    0.08%≦Ni≦0.20%;    1.10%≦Cr≦1.40%;    0.11%≦Mo≦0.25%;    0.08%≦Cu≦0.30%;    0.010%≦Al≦0.035%;    0.025%≦Nb≦0.040%;    0.0130%≦N≦0.0220%;    optionally trace levels≦Bi≦0.07% and/or trace levels≦Pb≦0.12% and/or trace levels≦Te≦0.010% and/or trace levels≦Se≦0.020% and/or trace levels≦Ca≦0.045%, the balance being iron and impurities resulting from the production operation.    
   
   
       5 . Method for producing a mechanical component from carburised or carbonitrided steel, wherein a steel according to  claim 1  is used for this purpose, on which a machining operation, carburising operation or carbonitriding operation is carried out, then a quenching operation.  
   
   
       6 . Method according to  claim 5 , wherein the carburising or carbonitriding is carried out at a temperature of from 950 to 1050° C.  
   
   
       7 . Steel mechanical component, wherein it is produced using the method according to  claim 5 .  
   
   
       8 . Mechanical component according to  claim 7 , wherein it is a gear component.