Flat steel product with an AI-coating, method for producing the same, steel component and method for producing the same

A steel component produced by hot press forming a flat steel product,

• wherein the flat steel product comprises:
• a steel substrate comprising 0.1-3% by weight Mn and 0.0005-0.01% by weight B;
• and
• a protective coating applied to the steel substrate, wherein the protective coating comprises 3-15% by weight Si, 0.05-0.5% by weight in total of one or more alloy constituents which have a greater affinity for oxygen than Al, and the remainder Al, wherein one of the alloy constituents is Mg and an Mg content of the protective coating is 0.05-0.5% by weight,
• wherein the steel component comprises an oxide of Mg and an oxide of Al each formed on an outer surface of the protective coating,
• wherein the steel component comprises a layer that forms a finish of the protective coating relative to surroundings, the layer including the alloy constituents and having a thickness of up to 200 nm, and
• wherein a hydrogen content of the steel substrate in the steel component is below 0.25 ppm by weight.

A steel component produced by hot press forming a flat steel product for hot forming, comprising:

• a steel substrate comprising 0.1-3% by weight Mn and 0.0005%-0.01% by weight B;
• and
• a protective coating applied to the steel substrate, the protective coating comprising 3-15% by weight Si, 0.105-0.5% by weight in total of at least two alloy constituents which have a greater affinity for oxygen than Al and are elements selected from the group consisting of alkaline earth and transition metals, and the remainder Al,
• wherein two of the alloy constituents are Mg and Sr,
• wherein an Mg content of the protective coating is 0.1-0.5% by weight and an Sr content of the protective coating is 0.005-0.25% by weight,
• wherein an oxide of the at least two alloy constituents selected from the group consisting of alkaline earth and transition metals is formed on an outer surface of the protective coating during hot forming of the flat steel product,
• wherein the alloy constituents are present in a layer that forms a finish of the protective coating relative to surroundings and has a thickness of up to 200 nm.

A method for producing a flat steel product, the method comprising:

• providing a steel substrate in a form of a flat steel product produced from a steel comprising 0.1-3% by weight Mn and 0.0005-0.01% by weight B;
• and
• coating the steel substrate with a coating that comprises 3-15% by weight Si, 0.105-0.5% by weight in total of at least two alloy constituents which have a greater affinity for oxygen than Al and are elements selected from the group consisting of alkaline earth and transition metals, and the remainder Al,
• wherein the alloy constituents comprise at least Mg, Ca, and Sr,
• wherein an Mg content of the protective coating is 0.1-0.5% by weight, a Ca content of the protective coating is at least 0.01% by weight, and an Sr content of the protective coating is 0.005-0.25% by weight.

A method for producing a steel component comprising:

• hot press forming a flat steel product that comprises a steel substrate comprising 0.1-3% by weight Mn and 0.0005-0.01% by weight B, and a protective coating applied to the steel substrate,
• wherein the protective coating comprises 3-15% by weight Si, 0.05-0.5% by weight in total of alloy constituents which have a greater affinity for oxygen than Al, and the remainder Al, and
• wherein one of the alloy constituents is Mg and an Mg content of the protective coating is 0.05-0.5% by weight,
• the method comprising:
• heating the flat steel product to a heating temperature for hot forming for an annealing time up to 800 s, wherein the heating occurs under an ambient atmosphere or under an H2O-reduced atmosphere;
• and
• hot forming the flat steel product to create the steel component,
• wherein an oxide of Mg and an oxide of Al are each formed on an outer surface of the protective coating,
• wherein the alloy constituents are present in a layer that forms a finish of the protective coating relative to surroundings and has a thickness of up to 200 nm, and
• wherein hydrogen diffusion into the steel substrate is 0.25 ppm by weight or less.