AUTOMOBILE COLUMN AND METHOD FOR PRODUCING A HOT-FORMED AND PRESS-HARDENED AUTOMOBILE COLUMN
An automobile column and to a method for producing an automobile column are disclosed. The automobile column has a region of a first type and a region of a second type which have mutually different strengths. A transition region having a width of less than 50 mm is formed between the two regions. The automobile column has in the region of the first type a bainitic structure and in the region of the second type a martensitic structure.
1 . An automobile column comprising:
at least two regions of different strength produced by hot-forming and press-hardening, wherein a region of a first type has after press-hardening a substantially bainitic structure and a region of a second type has after press-hardening a substantially martensitic structure, and
a transition region between the region of the first type and the region of second type being smaller than 80 mm.
2 . The automobile column of claim 1 , wherein the transition region is smaller than 50 mm.
3 . The automobile column of claim 1 , wherein the transition region is smaller than 30 mm.
4 . The automobile column of claim 1 , wherein the transition region is smaller than 20 mm.
5 . The automobile column of claim 1 , wherein the substantially martensitic structure of the region of the second type comprises additional structure components in a concentration of less than 50%.
6 . The automobile column of claim 1 , wherein the substantially martensitic structure of the region of the second type comprises additional structure components in a concentration of less than 30%.
7 . The automobile column of claim 1 , wherein the substantially martensitic structure of the region of the second type comprises additional structure components in a concentration of less than 15%.
8 . The automobile column of claim 5 , wherein the additional structure component comprises bainite.
9 . The automobile column of claim 1 , wherein the substantially bainitic structure of the region of the first type comprises additional structure components in a concentration of less than 50%.
10 . The automobile column of claim 1 , wherein the substantially bainitic structure of the region of the first type comprises additional structure components in a concentration of less than 30%.
11 . The automobile column of claim 1 , wherein the substantially bainitic structure of the region of the first type comprises additional structure components in a concentration of less than 15%.
12 . The automobile column of claim 1 , wherein the region of the first type is at least partially enclosed by the region of the second type.
13 . The automobile column of claim 12 , wherein the region of the first type is completely enclosed by the region of the second type.
14 . The automobile column of claim 1 , wherein the region of the first type is spot-shaped with a diameter of less than 40 mm.
15 . The automobile column of claim 1 , wherein the region of the first type is spot-shaped with a diameter of less than 20 mm.
16 . The automobile column of claim 1 , wherein the region of the first type is spot-shaped with a diameter of less than 10 mm.
17 . The automobile column of claim 1 , wherein the region of the first type is constructed as a flange, a connecting flange or an outside edge of the automobile column, or a combination thereof.
18 . The automobile column of claim 1 , wherein the region of the first type is formed in regions of the automobile column which are subject to strong deformations in a crash or which are configured to dissipate crash energy through deformations.
19 . The automobile column of claim 1 , wherein the region of the first type has an increased wall thickness in relation to the region of the second type.
20 . The automobile column of claim 1 , further comprising a passage or an edge, or both, in the region of the first type after hot-forming.
21 . The automobile column of claim 1 , wherein the region of the first type has a stretchability A 50 between 10% and 30%.
22 . The automobile column of claim 1 , wherein the region of the first type has a stretchability A 50 between 12% and 20%.
23 . The automobile column of claim 1 , wherein the region of the first type has a stretchability A 50 between 12% and 16%.
24 . The automobile column of claim 1 , wherein the region of the first type has a stretchability A 50 between 14% and 16%.
25 . The automobile column of claim 1 , wherein the region of the first type has a tensile strength between 500 and 1000 N/mm 2 .
26 . The automobile column of claim 1 , wherein the region of the first type has a tensile strength between 550 and 800 N/mm 2 .
27 . The automobile column of claim 1 , wherein a yield strength or a tensile strength decreases or increases in the transition region with a gradient of more than 100 N/mm 2 per 10 mm.
28 . The automobile column of claim 1 , wherein a yield strength or a tensile strength decreases or increases in the transition region with a gradient of more than 200 N/mm 2 per 10 mm.
29 . The automobile column of claim 1 , wherein a yield strength or a tensile strength decreases or increases in the transition region with a gradient of more than 400 N/mm 2 per 10 mm.
30 . The automobile column of claim 1 , wherein the region of the second type has a strength of more than 1000 N/mm 2 .
31 . The automobile column of claim 1 , wherein the region of the second type has a strength of more than 1200 N/mm 2 .
32 . The automobile column of claim 1 , wherein the region of the second type has a strength of more than 1400 N/mm 2 .
33 . The automobile column of claim 1 , wherein region of the first type has a yield strength between 200 and 800 N/mm 2 .
34 . The automobile column of claim 1 , wherein region of the first type has a yield strength between 250 and 600 N/mm 2 .
35 . The automobile column of claim 1 , wherein region of the first type has a yield strength between 250 and 500 N/mm 2 .
36 . The automobile column of claim 1 , wherein region of the first type has a yield strength between 300 and 500 N/mm 2 .
37 . The automobile column of claim 1 , wherein the automobile column is manufactured from a Tailor Welded Blank or a Tailor Rolled Blank.
38 . A method for producing a hot-formed and press-hardened automobile column having at least two regions of different hardness, said method comprising the steps of:
providing a hardenable metal plate or semi-finished product and heating the hardenable metal plate or semi-finished product to at least an austenizing temperature,
intermediately cooling a region of a first type of the metal plate or semi-finished product with a cooldown speed selected to be greater than a lower critical cooldown speed of a material of the metal plate or semi-finished product, and
hot-forming and press-hardening the metal plate or semi-finished product in a press-hardening tool to form the automobile column.
39 . The method of claim 38 , wherein a region of a second type is held above the austenizing temperature until the region of a second type is transported into the press-hardening tool.
40 . The method of claim 38 , wherein the cooldown speed during intermediate cooling of the region of the first type is selected such that a bainitic structure is obtained.
41 . The method of claim 40 , wherein the region of the first type is cooled to a cooling temperature between 600 and 400° C.
42 . The method of claim 41 , wherein the region of the first type is cooled to a cooling temperature of about 500° C.
43 . The method of claim 40 , wherein the region of the first type is held at the cooling temperature for a predetermined time.
44 . The method of claim 40 , wherein the region of the first type is held at the cooling temperature isothermally.
45 . The method of claim 38 , further comprising the step of quenching the region of the first type in the press-hardening tool from a bainitic structure transformation stage, whereby a mixed structure of martensite and bainite, or a mixed structure of martensite, bainite and at least one of ferrite and perlite, is adjusted in the region of the first type.
46 . The method of claim 38 , further comprising the step of holding the region of the first type isothermally so as to form a substantially pure bainitic structure by press-hardening.
47 . The method of claim 38 , wherein the cooldown speed of the intermediate cooling is selected to be greater than an upper critical cooling-down speed.
48 . The method of claim 38 , wherein the intermediate cooling of the region of the first type is performed in the press-hardening tool.
49 . The method of claim 48 , wherein the intermediate cooling of the region of the first type is performed by using cooling plates arranged in the press-hardening tool.
50 . The method of claim 38 , wherein the metal plate is pre-formed into a semi-finished product while cold before being heated to at least the austenizing temperature.