Deformation-hardened component made of galvanized steel, production method therefor and method for producing a steel strip suitable for the deformation-hardening of components

A deformation-hardened component made of galvanized steel by cutting a plate from a steel strip or steel sheet coated with zinc or with a zinc-based alloy and subsequently heating the plate to a deformation temperature above Ac3 for deformation and hardening, said galvanized steel having an at least partially martensitic transformation structure and comprising as a chemical composition in wt. %

• C:
• 0.10-0.50
• Si:
• 0.01-0.50
• Mn:
• 0.50-2.50
• P:
• <0.02
• S:
• <0.01
• N:
• <0.01
• Al:
• 0.015-0.100
• B:
• <0.004
• remainder iron, including unavoidable smelting-induced, steel-accompanying elements, wherein the chemical composition further comprises at least one element selected from the group consisting of Nb, V, Ti, with a sum of the contents Nb+V+Ti being in a range of 0.01 to 0.20 wt. %, wherein the structure of the steel after deformation-hardening comprises an average grain size of the former austenite grains of <15 μm.

A method for producing a steel strip suitable for deformation-hardening of a component, said method comprising:

• smelting a steel with a following chemical composition in wt. %
• C:
• 0.10-0.50
• Si:
• 0.01-0.50
• Mn:
• 0.50-2.50
• P:
• <0.02
• S:
• <0.01
• N:
• <0.01
• Al:
• 0.015-0.100
• B:
• <0.004
• remainder iron, including unavoidable smelting-induced, steel-accompanying elements, wherein the chemical composition further comprises at least one element selected from the group consisting of Nb, V, Ti, with a sum of the contents of Nb+V+Ti being in a range of 0.01 to 0.20 wt. %;
• casting the steel by a continuous casting process to form individual slabs with subsequent cooling in static air;
• reheating the slabs to a temperature in a range of 1200° C. to 1280° C.;
• hot-rolling the reheated slabs at a final rolling temperature in a range of 780° C. to 920° C. to form a hot strip;
• winding the hot strip at a temperature in the range of 630° C. to 750° C.;
• optional cold-rolling the hot strip with subsequent optional recrystallisation annealing;
• coating the hot-rolled or cold-rolled strip with zinc or a zinc-based alloy;
• and
• optional heat treatment to transfer the zinc coating or zinc alloy coating into a zinc-iron alloy layer.

A method for producing a deformation-hardened component from a steel strip, comprising:

• producing the steel strip by smelting a steel with a following chemical composition in wt. % C:
• 0.10-0.50, Si:
• 0.01-0.50, Mn:
• 0.50-2.50, P<0.02, S<0.01, N<0.01, Al:
• 0.015-0.100, B<0.004, remainder iron, including unavoidable smelting-induced, steel-accompanying elements, wherein the chemical composition further comprises at least one element selected from the group consisting of Nb, V, Ti, with a sum of the contents of Nb+V+Ti being in a range of 0.01 to 0.20 wt. %, casting the steel by a continuous casting process to form individual slabs with subsequent cooling in static air, reheating the slabs to a temperature in a range of 1200° C. to 1280° C., hot-rolling the reheated slabs at a final rolling temperature in a range of 780° C. to 920° C. to form a hot strip, winding the hot strip at a temperature in the range of 630° C. to 750° C., optional cold-rolling the hot strip with subsequent optional recrystallisation annealing;
• coating the hot-rolled or cold-rolled strip with zinc or a zinc-based alloy;
• and optional heat treatment to transfer the zinc coating or zinc alloy coating into a zinc-iron alloy layer;
• deforming the steel strip to form a slit pipe;
• welding the slit pipe along its strip edges;
• and
• deformation-hardening the welded slit pipe to form a component.