Hot press-formed member having excellent crack propagation resistance and ductility, and method for producing same

Abstract

Provided is a hot press-formed member having excellent crack propagation resistance and ductility. The hot press-formed member includes: a base steel sheet and a zinc or zinc alloy plating layer on at least one surface of the base steel sheet. The base steel sheet contains, by wt %, carbon (C): 0.08-0.30%, silicon (Si): 0.01-2.0%, manganese (Mn): 3.1-8.0%, aluminum (Al): 0.001-0.5%, phosphorus (P): 0.001-0.05%, sulfur (S): 0.0001-0.02%, nitrogen (N): 0.02% or less, and a balance of iron (Fe) and other impurities. The hot press-formed member comprises 1-30 area % of retained austenite as a microstructure, and a Mn(wt %)/Zn(wt %) content ratio in an oxide layer of 0.5-1.2 μm in a thickness direction from a surface layer of the plating layer is 0.1 or more.

1 . A hot press-formed member comprising:
 a base steel sheet; and
 a plating layer comprising Zn or Zn alloy on the base steel sheet, 
   wherein a Mn(wt %)/Zn(wt %) content ratio measured at a point 1 μm from a surface of the plating layer is 0.1 or more,   wherein a maximum crack depth penetrating the base steel sheet from an interface between the base steel sheet and the plating layer is 10 μm or less.   
     
     
         2 . The hot press-formed member of  claim 1 ,
 wherein a microstructure of the hot press-formed member comprises 1-30 area % of retained austenite.   
     
     
         3 . The hot press-formed member of  claim 1 ,
 wherein the microstructure of the hot press-formed member comprises 1-20 area % of retained austenite.   
     
     
         4 . The hot press-formed member of  claim 1 ,
 wherein the microstructure of the hot press-formed member comprises at least one of martensite and bainite, or at least one of tempered martensite and bainite.   
     
     
         5 . The hot press-formed member of  claim 1 ,
 wherein a prior austenite grain size of the hot press-formed member is 10 μm or less.   
     
     
         6 . The hot press-formed member of  claim 1 ,
 wherein a prior austenite grain size of the hot press-formed member is 7 μm or less.   
     
     
         7 . The hot press-formed member of  claim 1 ,
 wherein a prior austenite grain size of the hot press-formed member is 5 μm or less.   
     
     
         8 . The hot press-formed member of  claim 1 ,
 wherein the hot press-formed member comprises a metal coating comprising Fe or Ni between the base steel sheet and plating layer.   
     
     
         9 . The hot press-formed member of  claim 1 ,
 wherein the Mn(wt %)/Zn(wt %) content ratio is measured in an oxide layer of the plating layer.   
     
     
         10 . The hot press-formed member of  claim 1 ,
 wherein the base steel sheet comprises, by wt %, carbon (C): 0.08-0.30%, silicon (Si): 0.01-2.0%, manganese (Mn): 3.1-8.0%, aluminum (Al): 0.001-0.5%, phosphorus (P): 0.001-0.05%, sulfur (S): 0.0001-0.02%, nitrogen (N): 0.02% or less, and a balance of iron (Fe) and other impurities.   
     
     
         11 . The hot press-formed member of  claim 1 ,
 wherein the base steel sheet further comprises at least one selected from the group consisting of, by wt %,   (1) at least one of chromium (Cr) and molybdenum (Mo), a total content thereof being 0.001-2.0%;   (2) at least one of titanium (Ti), niobium (Nb), and vanadium (V), a total content thereof being 0.001-0.2%;   (3) at least one of copper (Cu) and nickel (Ni), a total content thereof being 0.005-2.0%; and   (4) Boron (B): 0.0001-0.01%.