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EP-4741524-A1 - STEEL ALLOY FOR PRODUCING A PROFILED BEAM AND METHOD FOR PRODUCING SAME

EP4741524A1EP 4741524 A1EP4741524 A1EP 4741524A1EP-4741524-A1

Abstract

The invention relates to a steel alloy for the production of a profile beam, comprising: C: 0.01% - 0.16% Si: 0.1% - 0.5% Mn: 1% - 1.7% Cr: 0% - 0.3% Mon: 0% - 0.1% Ni: 0% - 0.4% Cu: 0% - 0.55% N: 0% - 0.015% Note: 0.02% - 0.07% Ti: 0.005% - 0.05% V: 0.02% - 0.06% Al: 0% - 0.014% P: 0% - 0.02% P: 0% - 0.02% S: 0% - 0.02% Rest: Fe as well as unavoidable impurities.

Inventors

  • Liesner, Thomas

Assignees

  • Schwerter Profile GmbH

Dates

Publication Date
20260513
Application Date
20241111

Claims (12)

  1. Steel alloy for the manufacture of a profile beam, comprising: C: 0.01% -0.16% Si: 0.1% - 0.5% Mn: 1% - 1.7% Cr: 0% - 0.3% Mon: 0% - 0.1% Ni: 0% - 0.4% Cu: 0% - 0.55% N: 0% - 0.015% Note: 0.02% - 0.07% Ti: 0.005% - 0.05% V: 0.02% - 0.06% AI: 0%–0.014% P: 0% - 0.02% P: 0% - 0.02% S: 0% - 0.02% Rest: Fe as well as unavoidable impurities.
  2. Steel alloy according to claim 1, characterized in that the Al content is 0 - 0.010%.
  3. Steel alloy according to one of claims 1 or 2, characterized in that the Nb content is 0.025% - 0.05%, preferably 0.035% - 0.05%, and the V content is 0.02% - 0.04%.
  4. Steel alloy according to one of claims 1 to 3, characterized in that the N content is 0.008 - 0.015%.
  5. Steel alloy according to one of claims 1 to 4, characterized in that the Ti content is 0.006 - 0.015%.
  6. Steel alloy according to one of claims 1 to 5, characterized in that the Mn content is 1.2 - 1.65%, more preferably 1.55 - 1.65%.
  7. Steel alloy according to one of claims 1 to 6, characterized in that the Cu content is 0 - 0.45%.
  8. Steel alloy according to one of claims 1 to 5, characterized in that the alloy composition fulfills the following condition: 0,42 ≤ C + Si 8 + Mn 6 + Cr + Mo + V 5 + Ni + Cu 15 ≤ 0,55
  9. Steel alloy according to claim 8, characterized in that the lower limit is 0.44 and/or the upper limit is 0.54.
  10. Use of the steel alloy according to one of claims 1 to 9 for a guide profile, in particular a lifting mast for a forklift truck.
  11. Method for producing a steel alloy product from a steel alloy according to one of claims 1 to 9, characterized in that the steel alloy is cast into semi-finished products in a first step and hot-rolled above A C3 temperature in a second step and then cooled in moving air.
  12. Method according to claim 11, characterized in that machining is carried out after rolling.

Description

The invention relates to a steel alloy for manufacturing a highly stressed profile beam, in particular a guide beam. Such a guide beam is, for example, a lifting mast of a forklift truck. The invention further relates to a method for manufacturing a profile beam. Profile beams are beams for carrying loads that typically have a complex cross-section, such as an H-profile, U-profile, C-profile, etc. The profiling gives such a beam an improved section modulus, so that it can carry essentially the same loads at a lower weight compared to a solid beam. Guide rails are used in a variety of technical applications, particularly in industrial trucks and cranes, to ensure precise guidance, high stability, and reliable load transfer. In industrial trucks, especially in the masts of forklifts and other lifting vehicles, guide rails ensure precise movement of the telescopic sections and guarantee an even distribution of forces during the lifting process. This prevents the masts from tilting or jamming and enables safe and efficient handling of loads. In cranes, guide rails ensure the stable guidance of loads along the crane runway and, thanks to their robust construction, minimize vibrations and torsional forces. Further applications for guide rails are also known. Guide beams, especially lifting masts, are therefore highly stressed components in operation: Not only must they withstand high bending forces while maintaining the lowest possible weight, but also rolling over them. A lifting mast is required to withstand approximately 500,000 loaded rolling cycles. Considering the Hertzian contact pressure, these rolling cycles result in a highly localized compressive load on the profile. This necessitates a high surface hardness of the profile to ensure durability even under these conditions. to ensure the necessary dimensional accuracy under highly stressed conditions. In addition to the required high hardness, sufficient toughness is also required so that suddenly introduced loads, for example in an accident or in case of incorrect operation, do not lead to the profile beam breaking. Finally, good machinability, especially for cutting, is essential for the production of guide carriers. This includes both rolling into a specific profile shape and subsequent machining. Various alloys are known in the prior art. CN 116445810 A This document discloses a steel plate for wind turbines with a specific composition. In particular, it emphasizes that the aluminum content must be present in the alloy on a relatively large scale to prevent the titanium from binding and thus allowing it to be used for other purposes. CN 112553519 A A steel plate for a building component is revealed. Here, too, the deoxidizing effect of aluminum is mentioned, and it is therefore named as an essential component. DE 11 2021 006 024 T5 This concerns a steel plate for thick-walled pressure vessels. Here, too, a relatively high aluminum content is required. EP 3 872 206 B1 This concerns a process for flat steel production. Here, too, the aluminum content, which is defined as mandatory, is considered relatively high. The object of the invention is to provide an alloy that fulfills the aforementioned requirements. Furthermore, the invention provides a use of the steel alloy and a method for manufacturing a steel profile beam from the steel alloy. The alloy-related problem is solved by a steel alloy having the features of claim 1. A preferred use is specified in claim 7. The method is specified in claim 8. Advantageous embodiments result from the dependent claims and the description. Where a percentage is specified in these documents with regard to alloying elements, the corresponding content refers to wt.%. The alloying elements are referred to by their SI names. The core of the invention lies in the recognition that the specified alloy can meet the increased requirements for a guide beam, particularly a lifting mast, despite the alloy being relatively inexpensive in terms of material usage and simultaneously easy to process. The inventors consider it a special feature that the aluminum content in the alloy is significantly reduced and merely tolerated. Preferably, within the limits of what is technically feasible, the alloy is free of aluminum using scrap commonly used in steel production, meaning an aluminum content of < 0.010%. It has been observed that aluminum also binds the nitrogen contained in the alloy at an early stage during cooling (i.e., even at high temperatures during solidification). This is undesirable in this case, so that the nitrogen remains available for precipitation processes occurring at lower temperatures in conjunction with nitrogen and volatile matter. The optional and reduced use of aluminum minimizes the formation of coarse aluminum oxides, which increases the purity of the steel and improves its workability. This is particularly advantageous for applications requiring high toughness and ductility in addition to high hardness. I