Impact beam comprising precipitation hardenable stainless steel

Abstract

The present invention relates to an impact beam for use in a vehicle. More specifically, the invention relates to an impact beam comprising precipitation hardenable stainless steel, and a method of producing such a beam. The precipitation hardenable stainless steel has a composition, all in percent by weight, of: C max 0.07 Si max 1.2 Mn max 0.7 Cr 10-14 Mo max 1.5 Ni 7-12 Cu max 2.6 Ti 0.6-2.0 (Nb+Ta) max 0.7 balance Fe and normally occurring impurities. An impact beam comprising precipitation hardenable stainless steel, according to the invention, provides improved impact absorbing properties per unit of weight, and can be formed by conventional hot forming techniques.

1 . Impact beam comprising precipitation hardenable stainless steel, wherein the steel has a composition, all in percent by weight, of: 
     
       
         
               
               
               
             
                   
                   
               
                   
                 C 
                  max 0.07 
               
                   
                 Si 
                 max 1.2 
               
                   
                 Mn 
                 max 0.7 
               
                   
                 Cr 
                 10-14 
               
                   
                 Mo 
                 max 1.5 
               
                   
                 Ni 
                  7-12 
               
                   
                 Cu 
                 max 2.6 
               
                   
                 Ti 
                 0.6-2.0 
               
                   
                 (Nb + Ta) 
                 max 0.7 
               
               
               
             
                   
                 balance Fe and normally occurring impurities 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
              
              
              
              
             
          
           
              
              
             
          
         
       
     
   
   
       2 . Impact beam, according to  claim 1 , wherein the beam is adapted so as to absorb impact energy through deformation of the beam. 
   
   
       3 . Impact beam, according to  claim 1 , wherein the beam is adapted so as to transmit impact energy to an adjacent structure. 
   
   
       4 . Impact beam according to  claim 1 , wherein the stainless steel is UNS S45500. 
   
   
       5 . Impact beam according to  claim 1 , wherein the stainless steel is UNS S45503. 
   
   
       6 . Impact beam according to  claim 1 , wherein the stainless steel is UNS S46500. 
   
   
       7 . Impact beam according to  claim 1 , wherein the steel is precipitation hardened. 
   
   
       8 . Impact beam according to  claim 1 , wherein the beam structure comprises a cross section with at least two intersecting tangents defining a two-dimensional plane, wherein the structure is extended in a direction essentially perpendicular to the plane. 
   
   
       9 . Impact beam assembly, comprising an impact beam according to  claim 1 , and at least one part of a vehicle frame and/or a vehicle body structure. 
   
   
       10 . Impact beam assembly according to  claim 9 , wherein the impact beam is joined to at least one part of a vehicle frame and/or a vehicle body structure, by any technique. 
   
   
       11 . Method of producing an impact beam according to  claim 1 , wherein the impact beam is manufactured by hot forming. 
   
   
       12 . Method according to  claim 11 , wherein the impact beam is manufactured at a temperature equal to, or exceeding, 750° C., typically around 900° C. 
   
   
       13 . Method according to  claim 11 , wherein the hot forming technique is press hardening. 
   
   
       14 . Method according to  claim 11 , wherein the beam is subjected to precipitation hardening after hot forming 
   
   
       15 . Method according to  claim 11 , wherein at least a part of the surface of the beam is coated with a primer, such as a silicon based primer. 
   
   
       16 . Method according to  claim 12 , wherein the hot forming technique is press hardening