HIGHER-STRENGTH, COLD-FORMABLE STEEL AND STEEL SHEET PRODUCT CONSISTING OF SUCH A STEEL

摘要

#CMT# #/CMT# High-strength cold- molded steel comprises carbon (0.1-1 wt.%); manganese (10-25 wt.%); silicon (up to 0.5 wt.%); aluminum (0.3-2 wt.%); chromium (1.5-3.5 wt.%); sulfur (less than 0.03 wt.%); phosphorus (less than 0.08 wt.%); nitrogen (less than 0.1 wt.%); molybdenum (less than 2 wt.%); boron (less than 0.01 wt.%); nickel (less than 8 wt.%); copper (less than 5 wt.%); calcium (up to 0.015 wt.%); vanadium (0.01-0.5 wt.%) or niobium (0.01-0.5 wt.%); optionally titanium (0.01-0.5 wt.%); and iron and unavoidable pollutants (balance). #CMT# : #/CMT# An independent claim is included for flat steel products produced from the steel. #CMT#USE : #/CMT# The steel is useful for the manufacture of flat steel products (claimed), which are useful for the manufacture of body parts for motor vehicles #CMT#ADVANTAGE : #/CMT# The high-strength cold-molded steel exhibits good resistance to hydrogen-induced delayed cracking, good ductility and corrosion resistance. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Components: The amount of: carbon is 0.3-0.5 wt.%; manganese is 17-22 wt.%; silicon is at least 0.2 wt.%; aluminum is 0.5-1.5, preferably 0.5-1.3 wt.%; chromium is 1.7, preferably 1.8 wt.% or maximum 2.5, preferably 2.2 wt.%; nitrogen is 0.003-0.025 wt.%; nickel is less than 5 wt.%; copper is less than 3 wt.%; and calcium is at least 0.0015 wt.%. The steel exhibits tensile strength of at least 800 MPa. The flat steel product is coated with a metallic protective coating to the protection its surfaces from corrosion, where the metallic protective coating is formed by electrolytic galvanization, hot dip galvanization, fully annealed or galvannealed coating, zinc-nickel coating or hot-dip aluminization. #CMT#EXAMPLE : #/CMT# Typical cold-molded steel comprised of (in wt.%): carbon (0.418); manganese (19.3); silicon (0.48); aluminum (0.52); chromium (1.85); sulfur (0.007); phosphorus (0.004); nitrogen (0.0082); boron (less than 0.001); copper (less than 0.01); vanadium (0.12); niobium (less than 0.001); and titanium (less than 0.001).