METHOD FOR PRODUCING A FORMED COMPONENT FROM A STEEL BLANK, USE OF SUCH A COMPONENT, AND CORRESPONDING BLANK AND COMPONENT

Abstract

A method for producing a component from a blank made of a medium manganese steel having 4 to 12 wt. % Mn and a TRIP effect at room temperature, in which method the blank is mechanically cut to make a prepared blank having the desired dimensions, cut edges are produced on the prepared blank by means of mechanical cutting, and the prepared blank with the cut edges is cold-formed to obtain the component at room temperature or at a temperature above room temperature but below 60 C. The method is distinguished by cost-effective production, improved formability with reduced cracking at the formed cut edges, while simultaneously reducing the forming forces. The mechanical cutting is performed at a pre-heating temperature in the range of 60 C. to less than 250 C.

Claims

1. A method for producing a component from a plate comprising a medium manganese-containing steel with 4 to 12 wt. % Mn and with a TRIP effect at room temperature, wherein the method comprises: mechanically separating the plate to form a prepared plate with desired dimensions, and wherein separation edges are produced on the prepared plate by said mechanically separating the plate; and cold forming the prepared plate with the separation edges to form the component at room temperature or at a temperature above room temperature and below 60 C.; wherein said mechanically separating the plate is effected at a preheating temperature in the range of 60 C. to less than 250 C.

2. The method as claimed in claim 1, wherein the steel is a medium manganese-containing steel, with more than 5 to less than 10 wt. % Mn.

3. The method as claimed in claim 1, wherein the plate is heated locally to the preheating temperature only in regions of the separation edges to be produced by said mechanically separating.

4. The method as claimed in claim 1, wherein the preheating temperature is 100 to 200 C.

5. The method as claimed in claim 1, wherein the separation edges are heated to the preheating temperature in a heating device arranged in a cutting or punching tool.

6. The method as claimed in claim 1, wherein the separation edges are heated to the preheating temperature in a separate heating device.

7. The method as claimed in claim 5, wherein the separation edges are heated inductively, conductively or via radiant heat.

8. Use of a component produced according to claim 1 in at least one of automobile construction, rail vehicle construction, shipbuilding, plant construction, infrastructure construction, mining, the aerospace industry, and household appliance technology.

9. A prepared plate for producing a component by cold forming the prepared plate at room temperature, said prepared plate comprising: at least one separation edge of a mechanical separation from an original plate comprising a medium manganese-containing steel with 4 to 12 wt. % Mn and with a TRIP effect at room temperature; wherein the at least one separation edge determines or at least co-determines the dimensions of the prepared plate, and wherein TWIP effect-induced deformation twins are present in the microstructure at the separation edge.

10. A component comprising a plate of a steel with a TRIP effect at room temperature, wherein the plate is a prepared plate as claimed in claim 9.

11. The component as claimed in claim 10, produced by: mechanically separating the plate to form a prepared plate with desired dimensions, and wherein separation edges are produced on the prepared plate by said mechanically separating the plate; and cold forming the prepared plate with the separation edges to form the component at room temperature or at a temperature above room temperature and below 60 C.; wherein said mechanically separating the plate is effected at a preheating temperature in the range of 60 C. to less than 250 C.

12. The component as claimed in claim 10, wherein the component is a component for at least one of automobile construction, rail vehicle construction, shipbuilding, plant construction, infrastructure construction, mining, the aerospace industry, and household appliance technology.

13. The method as claimed in claim 6, wherein the separation edges are heated inductively, conductively or via radiant heat.

14. The method as claimed in claim 3, wherein the separation edges are heated to the preheating temperature.

15. The method as claimed in claim 14, wherein the separation edges are heated inductively, conductively or via radiant heat.

16. The method as claimed in 14, wherein the separation edges are heated to the preheating temperature in a heating device arranged in a cutting or punching tool, or the separation edges are heated to the preheating temperature in a separate heating device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a graph of hole expansion tests;

[0038] FIG. 2a is a scanning microscopy image of the formed sample of A1 shown in the graph of FIG. 1; and

[0039] FIG. 2b is a scanning microscopy image of the formed sample of A3 shown in the graph of FIG. 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The good results for the formability of separation edges produced in accordance with the invention become apparent from FIG. 1 for results of hole expansion tests according to ISO 16630, as illustrated in the appendix.

[0041] A TRIP/TWIP steel in wt. % with 0.14 C, 6 Mn, 0.15 Si and 1.2 Al, which has a TRIP effect at room temperature between 5 to 30 C., was selected for the tests. Holes were produced in a steel metal sheet by punching at different preheating temperatures and these were expanded at different temperatures in the course of the hole expansion test according to ISO 16630.

[0042] Sample A1 (light grey) was punched at room temperature (25 C.) and the expansion by means of the hole expansion test was also effected at room temperature (25 C.).

[0043] Sample A2 (dark grey) was punched at room temperature (25 C.) and expanded at 150 C.

[0044] Sample A3 (black) was punched at 150 C. and expanded at room temperature (25 C.).

[0045] Sample A4 (spotted) was punched at 150 C. and expanded at 150 C.

[0046] It is clearly apparent that the expansion value A (lambda) increases at a preheating temperature of the punching edge of 150 C. compared to punching at room temperature of 25 C. The value for sample A3 of =31.8% is significantly higher than the value of sample A1 of =14.18.

[0047] However, forming by hole expansion at an elevated temperature of 150 C. compared to forming at room temperature does not provide any significant improvement to the hole expansion ratio. The value for sample A2 with =16.92% is only slightly above the value of A1. The value for sample A4 with =35.40% is only slightly above the value of A3.

[0048] In addition, the micrographs obtained by scanning electron microscopy in FIG. 2a (sample A1, without preheating) and FIG. 2b (sample A3, with preheating) prove that significantly fewer and smaller cracks are produced on the formed cut edges when the punching procedure was effected on preheated samples.

[0049] In FIG. 2a which shows a scanning microscopy image of the formed sample A1 without preheated separation edges, cracks are very clearly visible as dark lines at the concavely curved separation edges. However, in FIG. 2b which shows a scanning microscopy image of the formed sample A3 with preheated separation edges, no such clear cracks are visible at the concavely curved separation edges.

[0050] In accordance with the invention, a use of a component produced according to the previously described method is advantageously provided in the automobile construction, rail vehicle construction, shipbuilding, plant construction, infrastructure construction, the aerospace industry, household appliance technology.

[0051] Provision is preferably made that the component is produced from a medium manganese-containing steel with the following chemical composition (in wt. %) in order to achieve in particular the described advantages: [0052] C: 0.0005 to 0.9, preferably 0.05 to 0.35; [0053] Mn: 4 to 12, preferably greater than 5 to less than 10 and with the remainder being iron including unavoidable steel-associated elements, with the optional addition by alloying of the following elements in wt. %: [0054] Al: 0 to 10, preferably 0.05 to 5, particularly preferably greater than 0.5 to 3; [0055] Si: 0 to 6, preferably 0.05 to 3, in a particularly preferred manner 0.1 to 1.5; [0056] Cr: 0 to 6, preferably 0.1 to 4, particularly preferably greater than 0.5 to 2.5; [0057] Nb: 0 to 1, preferably 0.005 to 0.4, in a particularly preferred manner 0.01 to 0.1; [0058] V: 0 to 1.5, preferably 0.005 to 0.6, in a particularly preferred manner 0.01 to 0.3; [0059] Ti: 0 to 1.5, preferably 0.005 to 0.6, in a particularly preferred manner 0.01 to 0.3; [0060] Mo: 0 to 3, preferably 0.005 to 1.5, in a particularly preferred manner 0.01 to 0.6; [0061] Sn: 0 to 0.5, preferably less than 0.2, in a particularly preferred manner less than 0.05; [0062] Cu: 0 to 3, preferably less than 0.5, in a particularly preferred manner less than 0.1; [0063] W: 0 to 5, preferably 0.01 to 3, in a particularly preferred manner 0.2 to 1.5; [0064] Co: 0 to 8, preferably 0.01 to 5, in a particularly preferred manner 0.3 to 2; [0065] Zr: 0 to 0.5, preferably 0.005 to 0.3, in a particularly preferred manner 0.01 to 0.2; [0066] Ta: 0 to 0.5, preferably 0.005 to 0.3, in a particularly preferred manner 0.01 to 0.1; [0067] Te: 0 to 0.5, preferably 0.005 to 0.3, in a particularly preferred manner 0.01 to 0.1; [0068] B: 0 to 0.15, preferably 0.001 to 0.08, in a particularly preferred manner 0.002 to 0.01; [0069] P: less than 0.1, preferably less than 0.04; [0070] S: less than 0.1, preferably less than 0.02; and [0071] N: less than 0.1, preferably less than 0.05.

[0072] This composition is provided both for the plate and for the component produced therefrom. The plate preferably has a microstructure with the following proportions: 10 to 80 vol. % austenite, 20 to 90 vol. % martensite, ferrite and bainite, wherein at least vol. % of the martensite is present as tempered martensite. In a particularly preferred manner, the microstructure has 40 to 80 vol. % austenite, less than 20 vol. % ferrite/bainite, with the rest being martensite.

[0073] In the case of the microstructure of the resulting component, the corresponding proportions are preferably present approximately in the same limits as in the case of the plate.

[0074] The information regarding composition and microstructure corresponds to that from the document DE 10 2016 117 494 A1 mentioned in the introduction. Effects of the alloy elements used can be found in this document.