SSAB has been granted a patent for a hot-rolled steel with a tensile strength of at least 950 MPa. The steel has a microstructure consisting of bainite at an area ratio of 70% or more, martensite at an area ratio of 30% or less, and optionally ferrite at an area ratio of 20% or less. The chemical composition includes specific percentages of carbon, silicon, manganese, chromium, nickel, copper, molybdenum, aluminum, niobium, vanadium (optional), and titanium (optional). The remaining composition is iron and unavoidable impurities. GlobalData’s report on SSAB gives a 360-degree view of the company including its patenting strategy. Buy the report here.

According to GlobalData’s company profile on SSAB, gas pipeline network monitoring was a key innovation area identified from patents. SSAB's grant share as of June 2023 was 1%. Grant share is based on the ratio of number of grants to total number of patents.

Patent granted for hot-rolled steel with specific microstructure and composition

Source: United States Patent and Trademark Office (USPTO). Credit: SSAB AB

A recently granted patent (Publication Number: US11655528B2) describes a hot-rolled steel with specific characteristics and a method for manufacturing it. The steel has a minimum tensile strength of 950 MPa and a microstructure consisting of bainite, martensite, and optionally ferrite. The microstructure is primarily composed of upper bainite, with martensite and ferrite present in smaller proportions. The chemical composition of the steel includes specific percentages of carbon, silicon, manganese, chromium, nickel, copper, molybdenum, aluminum, niobium, vanadium, titanium, and iron.

The patent also claims that the hot-rolled steel can have a yield strength ranging from 720 to 950 MPa, an elongation of at least 8%, and a hole expansion ratio of at least 25%. Additionally, the steel can have a thickness of 4 mm or less. The patent further mentions that the hot-rolled steel can be used in vehicles, particularly automotive vehicles.

The method for manufacturing the hot-rolled steel involves several steps. First, a steel with the specified chemical composition is heated to a temperature of at least 1250°C. Then, the steel is hot-rolled at a finishing rolling temperature of 850-930°C. After hot-rolling, the steel is quenched to a coiling temperature of 450-575°C and then coiled at that temperature. The steel is subsequently cooled and subjected to a skin pass rolling step. The skin pass rolling is performed at a reduction of 0.5-2%. The quenching step is carried out at a rate of at least 60°C/s, and the cooling step is done at a cooling rate of 10°C/s or less.

In summary, this granted patent describes a specific hot-rolled steel with a unique microstructure and chemical composition, as well as a method for manufacturing it. The steel exhibits high tensile strength, yield strength, elongation, and hole expansion ratio, making it suitable for use in vehicles, particularly automotive vehicles. The manufacturing process involves precise heating, hot-rolling, quenching, coiling, cooling, and skin pass rolling steps to achieve the desired properties of the steel.

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GlobalData Patent Analytics tracks bibliographic data, legal events data, point in time patent ownerships, and backward and forward citations from global patenting offices. Textual analysis and official patent classifications are used to group patents into key thematic areas and link them to specific companies across the world’s largest industries.