Method for Manufacturing a Product from a Flexibly Rolled Strip Material

Abstract

A method for manufacturing a product from a flexibly rolled strip material includes the steps of: providing a strip material made from sheet steel; flexibly rolling the strip material such that a variable thickness is produced along the length of the strip material; electrolytically coating the strip material with a metallic coating material containing at least 93% of zinc by mass after the flexible rolling; heat treating at temperatures above 350° C. and below a solidus line of the coating material after the electrolytic coating; working a blank from the flexibly rolled strip material; and hot forming the blank.

What is claimed is: 
     
         1 . A method for manufacturing a product from a flexibly rolled strip material comprising the steps of:
 providing a strip material made from hardenable sheet steel,   flexible rolling the strip material, wherein a variable thickness is produced along the length of the strip material,   electrolytically coating the strip material with a metallic coating material that contains at least 93% by mass of zinc, wherein the electrolytic coating is carried out after the flexible rolling,   heat treating the strip material at temperatures above 350° C. and below a solidus line of the coating material, wherein the heat treatment is carried out after the electrolytic coating,   working a blank from the flexibly rolled strip material, and   hot forming the blank.   
     
     
         2 . The method according to  claim 1  wherein the metallic coating material has a minimum of 5% by mass of iron and a maximum of 7% by mass of iron. 
     
     
         3 . The method according to  claim 2  wherein the proportions of zinc and iron in the coating material are selected such that at least partially δ1-phase is present after the step of electrolytically coating the strip of material. 
     
     
         4 . The method according to  claim 2  wherein the temperature is increased during the heat treatment. 
     
     
         5 . The method according to  claim 2  wherein the heat treatment is carried out inductively or by means of annealing in a bell-type annealing furnace, wherein the annealing is carried out with a holding time of 10 hours to 80 hours. 
     
     
         6 . The method according to  claim 1  wherein before the electrolytically coating step, the strip material is coated with an intermediate layer. 
     
     
         7 . The method according to  claim 6  wherein the intermediate layer contains nickel or aluminum or manganese. 
     
     
         8 . The method according to  claim 1  wherein after the electrolytically coating step, a scaling prevention is deposited. 
     
     
         9 . The method according to  claim 1  wherein the hot forming includes the steps of:
 cold pre-forming of the blank to a cold pre-formed component, 
 heating at least a partial area of the cold pre-formed component up to austenitization temperature, and 
 hot post-forming of the cold pre-formed component for producing a final contour. 
 
     
     
         10 . The method according to  claim 1  wherein the hot forming step includes the steps of:
 heating at least a partial area of the blank up to the austenitization temperature, and 
 hot forming of the blank for producing a final contour. 
 
     
     
         11 . The method according to  claim 1  wherein at a point of time when initiating the hot forming step, the coating material is in a solid state.