Stabilizer bar

Abstract

A tubular stabilizer bar for a vehicle suspension is formed from an as-quenched steel material that is not subjected to a tempering process, and which has a hardness of at least 40 Rockwell C. The stabilizer bar includes an ultimate tensile strength that is greater than 200 ksi with a ratio of yield strength to ultimate tensile strength that is no more than 0.9. The stabilizer bar is significantly harder and has significantly improved fatigue life without compromising ductility, when compared with prior designs.

1 . A method for forming a tubular stabilizer bar including: 
 (a) quenching stabilizer bar tubing material formed from a lower carbon content steel having a carbon content of approximately 0.07-0.40% to produce an as-quenched stabilizer bar tube; and    (b) forming a final stabilizer bar from the as-quenched stabilizer bar tube from step (a) having a hardness of at least 40 Rockwell C.    
   
   
       2 . The method according to  claim 1  including the steps of applying a paint to the as-quenched stabilizer bar tube and curing the paint subsequent to steps (a) or (b).  
   
   
       3 . The method according to  claim 2  wherein step (a) provides the as-quenched stabilizer bar tube with a first hardness value and wherein curing the paint provides the as-quenched stabilizer bar tube with a second hardness value that is less than the first harness value.  
   
   
       4 . The method according to  claim 1  wherein step (b) includes providing the hardness of at least 40 Rockwell C without tempering the as-quenched stabilizer bar tube subsequent to step (a).  
   
   
       5 . The method according to  claim 4  including providing the final stabilizer bar with an ultimate tensile strength of at least 200 ksi.  
   
   
       6 . The method according to  claim 1  wherein step (a) is the only heat treating step applied to the stabilizer bar tubing material.  
   
   
       7 . The method according to  claim 1  wherein the hardness is at least 42 Rockwell C.  
   
   
       8 . The method according to  claim 1  wherein the carbon content is approximately 0.20-0.35%.  
   
   
       9 . A stabilizer bar for a suspension assembly comprising: 
 a tubular body having a hardness of at least 40 Rockwell C without tempering.    
   
   
       10 . The stabilizer bar according to  claim 9  wherein said tubular body is comprised of an as-quenched lower carbon steel material.  
   
   
       11 . The stabilizer bar according to  claim 10  wherein said tubular body is non-tempered.  
   
   
       12 . The stabilizer bar according to  claim 9  wherein said tubular body includes a cured paint coating.  
   
   
       13 . The stabilizer bar according to  claim 9  wherein said tubular body is formed from a material having a ratio of yield strength to ultimate tensile strength that is less than 0.9.  
   
   
       14 . The stabilizer bar according to  claim 13  wherein said material has an ultimate tensile strength of at least 200 ksi.  
   
   
       15 . The stabilizer bar according to  claim 9  wherein said hardness is at least 42 Rockwell C.  
   
   
       16 . The stabilizer bar according to  claim 9  wherein said tubular body has a percent elongation property of at least 15% and a percent reduction in area property of at least 46%.  
   
   
       17 . The stabilizer bar according to  claim 9  wherein said tubular body is formed from a lower carbon content steel having a carbon content of approximately 0.07-0.40%.  
   
   
       18 . The stabilizer bar according to  claim 17  wherein the carbon content is approximately 0.20-0.35%.