Method of production of parts of ahs steel by controlled local cooling by a cooling medium and by interrupted cooling at required temperature to create a multiphase microstructure

Abstract

This invention generally relates to a method for producing parts of AHS steel via a controlled local cooling by a cooling medium and an interrupted cooling at a required temperature, without immersion in a cooling bath, to thereby create a multiphase microstructure. Typically, the steel part may be cooled by a jet of cooling medium so that, depending on the amount of heat which needs to be removed from the surface of the part, the locations from which a larger amount of heat needs to be removed are cooled at a higher intensity.

What is claimed is: 
     
         1 . A method for producing AHS steel parts, the method comprising:
 (a) cooling of a steel part at controlled locations by a jet of cooling medium at a first temperature; and   (b) cooling the steel part at a designated temperature that is different from the first temperature to thereby create a multiphase microstructure, wherein the cooling of step (b) occurs at one or more intervals between the cooling of step (a),   wherein the first temperature of the cooling of step (a) may be adjusted depending on the amount of heat that needs to be removed from a surface of the steel part.   
     
     
         2 . The method of according to  claim 1 , wherein thin regions of the steel part that contain less steel material relative to thicker regions of the steel part that contain more steel material are cooled in a controlled fashion during the cooling of step (a) and the cooling of step (b) so that an undercooling temperature in the thin regions is higher than a minimum required cooling temperature. 
     
     
         3 . The method according to  claim 1 , wherein a uniform temperature is maintained on the surface of the steel part. 
     
     
         4 . The method according to  claim 1 , wherein the cooling of step (a) and the cooling of step (b) are affected by a nozzle.