Method of manufacturing hot press-formed part, and hot press-formed part

Abstract

A method of manufacturing a hot press-formed part by hot pressing a coated steel sheet formed with a Zn—Ni plating layer on a surface of a steel sheet includes: heating the coated steel sheet to a temperature range of Ac 3 transformation temperature to 1000° C.; cooling the coated steel sheet to 550-410° C. at a cooling rate of 100° C./s or higher by squeezing the coated steel sheet with a press tool for cooling having flat surfaces configured to contact the coated steel sheet; press forming the coated steel sheet with a tool of press forming to obtain a formed body, the press forming being initiated within 5 seconds after the cooling while the temperature of the coated steel sheet is 550-400° C.; and quenching the formed body, while squeezing the formed body with the tool of press forming and holding at its press bottom dead center, to obtain a hot press-formed part.

1 . A method of manufacturing a hot press-formed part by hot pressing a coated steel sheet formed with a Zn—Ni plating layer on a surface of a steel sheet, the method comprising:
 heating the coated steel sheet to a temperature range of Ac 3  transformation temperature to 1000° C.; 
 cooling the heated coated steel sheet to a temperature of 550° C. or lower and 410° C. or higher, at a cooling rate of 100° C./s or higher, by squeezing the coated steel sheet with a press tool for cooling having flat surfaces configured to contact the coated steel sheet; 
 press forming the coated steel sheet with a tool of press forming to obtain a formed body, the press forming being initiated within 5 seconds after the cooling while the temperature of the coated steel sheet is 550° C. or lower and 400° C. or higher; and 
 quenching the formed body, while squeezing the formed body with the tool of press forming and holding at its press bottom dead center, to obtain a hot press-formed part. 
 
     
     
         2 . The method of manufacturing a hot press-formed part according to  claim 1 , wherein the Zn—Ni plating layer of the coated steel sheet contains 9 mass % or more and 25 mass % or less of Ni. 
     
     
         3 . A hot press-formed part manufactured by the method as recited in  claim 1 . 
     
     
         4 . A hot press-formed part manufactured by the method as recited in  claim 2 .