Sheet steel for use as packaging steel and method for producing packaging steel

Abstract

The invention relates to sheet steel for use as packaging steel, made of a non-alloy or low-alloy and cold-rolled steel having a carbon content of less than 0.1%. According to the invention, in order to use such sheet steel for packaging steel that has good formability and can be produced in a cost-effective way, the sheet steel contains less than 0.4 wt % of manganese, less than 0.04 wt % of silicium, less than 0.1 wt % of aluminum, and less than 0.1 wt % of chromium and is provided with a multi-phase structure, comprising ferrite and at least one of the structure constituents martensite, bainite, and/or residual austenite. The invention further relates to a method for producing such packaging steel from cold-rolled sheet steel.

1 . Sheet steel for use as packaging steel made from a nonalloy or low alloy and cold rolled steel having a carbon content of less than 0.1%, wherein the sheet steel contains less than 0.4 wt % manganese, less than 0.04 wt % silicon, less than 0.1 wt % aluminum, and less than 0.1 wt % chromium, and has a multiphase structure, which comprises ferrite and at least one of the structural components martensite, bainite, and/or residual austenite. 
     
     
         2 . Method for making a packaging steel from a cold rolled sheet steel which is made from a nonalloy or low alloy steel having a carbon content of less than 0.1%, wherein the sheet steel is first subjected to a recrystallization annealing by means of electromagnetic induction at a heating rate of more than 75 K/s and is cooled after the recrystallizing induction annealing at a cooling rate of at least 100 K/s and preferably more than 500 K/s, through which a multiphase structure develops, which comprises ferrite and at least one of the structural components martensite, bainite, and/or residual austenite. 
     
     
         3 . Method as in  claim 2 , wherein the low alloy steel contains less than 0.4 wt % Mn, less than 0.04 wt % Si, less than 0.1 wt % Al, and less than 0.1 wt % Cr. 
     
     
         4 . Sheet steel as in  claim 1 , wherein the multiphase structure contains more than 80% and preferably at least 95% of the structural components, ferrite, martensite, bainite, and/or residual austenite. 
     
     
         5 . Sheet steel as in  claim 1 , wherein the sheet steel is made from a low alloy steel, which contains boron and/or niobium and/or titanium. 
     
     
         6 . Sheet steel as in  claim 1 , wherein the sheet steel is a cold rolled fine or ultrafine sheet. 
     
     
         7 . Sheet steel as in  claim 1 , wherein the sheet steel is coated with a surface coating of tin, chromium, aluminum, zinc, or zinc/nickel after the recrystallization annealing and cooling. 
     
     
         8 . Sheet steel as in  claim 1 , wherein the sheet steel has a tensile strength of at least 500 MPa, preferably more than 650 MPa, and an elongation at break of more than 5%, preferably more than 10%, after the recrystallization annealing and cooling. 
     
     
         9 . Sheet steel as in  claim 1 , wherein the cooling rate at which the sheet steel is cooled after the recrystallization annealing is greater than 100 K/s and preferably greater than 500 K/s. 
     
     
         10 . Sheet steel as in  claim 1 , wherein the sheet steel is made from a low alloy steel with the following upper limits for the weight fraction of the alloy components:
 N: max. 0.02%,   Mn: max. 0.4,   Si: max. 0.04%,   Al: max. 0.1%,   Cr: max. 0.1%,   P: max. 0.03%,   Cu: max. 0.1%,   Ni: max. 0.1%,   Sn: max. 0.04%,   Mo: max. 0.04%,   V: max. 0.04%,   Ti: max. 0.05%, preferably less than 0.02%;   Nb: max. 0.05%, preferably less than 0.02%;   B: max. 0.005%   and other alloying components including contaminants: max. 0.05%.   
     
     
         11 . Method as in  claim 2 , wherein the sheet steel after the recrystallizing induction annealing, is cooled by a cooling fluid at a cooling rate between 100 K/s and 1000 K/s and preferably at a cooling rate between 350 and 1000 K/s. 
     
     
         12 . Method as in  claim 2 , wherein the recrystallization annealing takes place in a time interval of 0.5 to 1.5 s, preferably about 1 s, where the sheet steel is inductively heated to temperatures above 720° C. 
     
     
         13 . Use of a sheet steel as in  claim 1  as packaging steel, in particular for making cans for foods, beverages, and other materials such as chemical or biological products and for making aerosol cans and closures. 
     
     
         14 . Method as in  claim 2 , wherein the multiphase structure contains more than 80% and preferably at least 95% of the structural components, ferrite, martensite, bainite, and/or residual austenite. 
     
     
         15 . Method as in  claim 2 , wherein the sheet steel is made from a low alloy steel, which contains boron and/or niobium and/or titanium. 
     
     
         16 . Method as in  claim 2 , wherein the sheet steel is a cold rolled fine or ultrafine sheet. 
     
     
         17 . Method as in  claim 2 , wherein the sheet steel is coated with a surface coating of tin, chromium, aluminum, zinc, or zinc/nickel after the recrystallization annealing and cooling. 
     
     
         18 . Method as in  claim 2 , wherein the sheet steel has a tensile strength of at least 500 MPa, preferably more than 650 MPa, and an elongation at break of more than 5%, preferably more than 10%, after the recrystallization annealing and cooling. 
     
     
         19 . Method as in  claim 2 , wherein the cooling rate at which the sheet steel is cooled after the recrystallization annealing is greater than 100 K/s and preferably greater than 500 K/s. 
     
     
         20 . Method as in  claim 2 , wherein the sheet steel is made from a low alloy steel with the following upper limits for the weight fraction of the alloy components:
 N: max. 0.02%,   Mn: max. 0.4,   Si: max. 0.04%,   Al: max. 0.1%,   Cr: max. 0.1%,   P: max. 0.03%,   Cu: max. 0.1%,   Ni: max. 0.1%,   Sn: max. 0.04%,   Mo: max. 0.04%,   V: max. 0.04%,   Ti: max. 0.05%, preferably less than 0.02%;   Nb: max. 0.05%, preferably less than 0.02%;   B: max. 0.005%   and other alloying components including contaminants: max. 0.05%.