DE1608213B1 - PROCESS FOR THE MANUFACTURING OF A HOT AND / OR COLD-FINISHED ROLLED STRIP AND FORMED PRODUCTS FROM FERRITI SCHEM CHROME STEEL - Google Patents

Description

1 2

The invention relates to a method for the production

development of a hot-rolled and / or cold-finish-rolled strip. Usually the

of the sheet metal made from it and from it, hot strip annealing of these steels in the hood annealing

preferably cold, formed products-aiis oven at 800 to 850 ⁰ C with treatment times of 24

ferritic chromium steel with high corrosion resistance 5 to 30 hours (see magazine »Metallkunde«, 1963,

durability and a smooth surface, whereby the warm p. 724 to 728, as well as the magazine »Bänder, Bleche,

band is subjected to a hood annealing. Pipes ", 1963, pp. 61 to 69).

In the manufacture and use of ferritic materials, this compromise between the opposing

Steels with 13 to 18% chromium and a maximum of 0.15% in accordance with requirements for a rapid production process and

Carbon, similar to DIN designation X 8 Cr 17, io high surface quality is not satisfactory because

Material no. 1.4016, and similar to the US standard as a result of the annealing treatment described above

AISI type 430, are the surface propertiesB. a strong, firmly adhering layer of scale is formed

Strips and the sheets and molds made from them. A multitude of complex operations

parts (e. g., deep-drawn objects) of special is required, first through KomMoation

Meaning. A decisive criterion for the use of mechanical and / or chemical processes

reversibility of both the rolled products and the descaling of the surface and then the

Finished parts is the surface quality, unevenness. Eliminate surface roughness in the course of

(e.g. excessive roughness) and other defects annealing treatment and also the descaling treatment

visually annoying to everyone and can enter through it.

can also be recorded using measurement technology. With the same 20 With conventional hood annealing in the area The permanent alloy composition decreases from 800 to 850 ° C and a second disadvantage occurs Corrosion resistance with decreasing surface appearance, namely the so-called chrome quality also from. It has therefore long been one of the poor. The chromium content can be close to the surface the most important concern of all steel manufacturers, as far as possible shifts locally e.g. B. decrease from 17 to 12% what The high surface quality of the rust-resistant flat surface naturally affects the corrosion resistance of the products to achieve. These efforts cause the band in question to have a very detrimental effect. the However, in conventional strip production a chromium depletion is indeed considerable due to the removal Reduced effort in the most varied of work effects during subsequent pickling operations, stages. After the necessary annealing, the warm but not eliminated.

rolled strips, the surface is heavily scaled 30 had to be in the corresponding stainless steel works

and needs to be cleaned. For this purpose, special mechanical operating procedures are used for descaling

And / or chemical processes are used that are created in addition to treatment. Usually the

The disadvantage of the cost is that the surface of the strip is initially blast-descaled (e.g. with

Surface deterioration of the metallic base steel shot), then the remaining

Depend on the material. 35 scale particles removed by chemical baths.

This means that the descaled raw strips are naturally roughened up due to this distortion of parts with high demands on the scaling. This roughness, surface quality unsuitable. It belongs to the state of the art that had to be accepted so far, is with technology to re-roll the raw strips cold. Measurable with star surface probing devices (ζ. B. Perth-O-Meter, no deformation must, however, again anneal 40 see Stahl und Eisen S3 [1963], S- ) & 6 to 344). Pickling treatments will be switched on, which will determine the absolute surface roughness Rt (see DIN lent scale and roughness test according to 4767),

draw. The predominant amount of ferritic chromium- With descaled hot strips 13 to 18% igar steel strips must currently be used in the course of production. Such roughness values impair the upper forming into finished parts - mechanically, chemically or surface gloss and the polishing ability of the strips, especially since they are electrochemically post-treated (by grinding also after cold rolling as well as after furnace, buffing, polishing, etc. .). A high-gloss _a further deformation remain recognizable. At the same time rust-resistant, ferritic chromium steel tape, at 50 this roughness has a negative effect on the corrosion of it. Processing based on the special treatment resistance. This is particularly harmful, as it can be drawn, was not previously known. the chromium content of the near-surface layers below

Usually the 13 to 18 ⁰ JJgSn, ferri- em of the Giujjdmaterials,

tables chrome steels as hot strip in the hood annealing To eliminate these disadvantages, in particular oven treated. This annealing is said to be the result of the 55 roughness, different operations are one-hot rolling present, line-stretched con- were made. For example, there are cold rolling concentration differences as far as possible are used (type S e η d ζ i m i r), where and cause irregular grain growth. Frequent roll changes result in a smoothing of the it is known to every person skilled in the art that such a belt surface should be produced. Furthermore, the Structural homogenization by means of a higher annealing temperature- 60 belt sent over grinding systems. Such maturities is accelerated. On the other hand, there is the upper machine, each with a pay-off and a take-up reel surface - despite the usual use of a protective layer - can be combined, jmjssen, reach a length gas atmosphere - due to increased annealing temperatures of about 30 to 40 m. The stainless strips are worsened, this worsening with increasing - be it in hot strip thickness, be it in intermediate thicknesses Temperatures increases progressively. By 65 ken - once or several times in the course of the manufacturing process both requirements - on the one hand, the homogenization process is sent over these so-called »grinding lines«, tion, on the other hand usable surface - fair It is known to every person skilled in the art that after a the annealing temperature is limited to 850 ° C. »Pre-grinding«, which causes material to be removed

a "finish sanding" has to be switched on, bpi that with a fine-grained abrasive the surface roughness is to be reduced again, this solidifies in the course of cold rolling Band as a result of cold deformation. In this state it is unsuitable for much further processing ^ purposes, in particular for deep drawing, pressing, bending, folding etc. Deformation to be soft annealed; in the case of strong degrees of deformation, there is also a final annealing intermediate annealing is also required. Continuous furnaces have been used for these annealing treatments introduced. The same applies to the selection of the annealing temperature as for hood annealing, i.e. H., Temperatures between .800 and 85O ° C are common as a compromise between the opposing requirements after complete recrystallization on the one hand and protection of the surface on the other. The total furnace time is usually between 1 and 10 minutes, depending on the thickness of the strip. As with this annealing too If scaling occurs again in normal furnaces, the use of "bright annealing furnaces" is different. has been provided; however, these have structural and operational expenses because of 4 no general introduction found. In addition, the "bright annealing" has two further disadvantages themselves; on the one hand, the common protective gases contain nitrogen, so that the chrome steel strip on the Surface is embroidered in an undesirable manner, on the other hand, the bright annealing favors the extent the chromium depletion, since no removal of the chromium-depleted surface layer takes place.

For the reasons described, annealing is usually carried out in so-called "open continuous furnaces". The one with it Any scaling that occurs is eliminated in continuous pickling baths (so-called pickling lines). In this Stage 4 production prohibits the use of jet descaling machines, which are fast and work effectively, but the finish-rolled strip surprisingly avoided the disadvantages indicated. The surface and corrosion resistance of ferritic chromium steels is improved by according to the invention

a) Verr the following, but known, steel composition for the production of the belt is applied, namely in the alloy range I with

0.05 to 0.15% carbon, 0 to 0.50% silicon

0.50 to 3.50% manganese
13.0 to 18.00% chromium

0.30 to 2.50% nickel

0 to 0.40% molybdenum

0.050 to 0.25% nitrogen

0 to 0.50% copper

0 to 0.15% cobalt

0 to 0.08% aluminum, remainder iron and impurities

or in alloy range II with 0.065 to 0.135% carbon

0 until 0.350% silicon 0.6 until 2,000% manganese 13.5 until 16.800% chrome 0.45 until 1,800% nickel 0 until 0.300% molybdenum 0.055 ! until 0.130% nitrogen 0.02 until 0 ₅ 300% copper 0 until 0.130% cobalt 0 until 0.050% aluminum Remainder iron and impurities, and

b) the box annealing of the hot strip in the temperature range of 650 to 780 ° C, preferably ⁰ to 760 C, is carried out in the range of 700th

A major advantage of the invention is that the measure to b) without extension

would roughen in an inadmissible manner. Therefore 40 of the usual annealing time can be carried out, must here with several successive pickling The annealing material is treated so that it is in the area baths are worked. There are numerous above temperatures for 1 to 30 hours beat and occasionally other company loyalty is held.

sings become known, z. B, the pickling in salt- If that according to the method according to the invention

biäder, 4h serve the purpose of improving the surface quality of these chromium steel strips and reasons, for example to achieve a thin sheet of 45 produced, hot-rolled strip with little effort can be the prior art, then still cold rolled, and, wi $ must therefore described above, a considerable it was then-in between levels, be it in Licher Endstärke- expenditure of annealing treatments, smooth, pickling annealed in known manner 50 is, so sees the present and grinding processes are operated to a the de invention for this intermediate or final annealing

several possibilities.

Either this single or multiple annealing can be carried out in a manner known per se in the range of 800 up to 850 ° C. Surprisingly, however, it has been shown that the possibility exists to produce a flawless cold strip, if for the intermediate and / or final annealing reduced temperatures «are kept

OPTICAL PYROMETRY «, Verlag G. Braun, 6p den. Improving the surface quality and Karlsruhe), corrosion resistance occurs in particular,

It remains unsatisfactory, that the chromium content when said annealing in the range 650 of the surface layer by 2 to 5% on the base to 800 ⁰ C, preferably 700-780 ° C, is lowered material are performed.

Here, the object of the present invention is based on a further variant of the method a. Intermediate and / or final annealing in the area

The applicant has found a new method. carried out between 500 and 650 ° C.
It is important that the advantages according to the invention are achieved by a combination of two measures

Requirements in practice to produce approximately corresponding cold-rolled, ferritic strip, its physical properties are in the following range:

a) surface roughness 0.5 to 3 μ;

b) Reflectivity about 65% (see Euler, Ludwig; »ARBEITSMETHODE DER

even with such annealing times for the intermediate and / the qualitative improvement of the intermediate and

or final annealing, which resulted in the previously finished products, is not up to now

Do not exceed the usual limits. recognized.

From the according to the above-described ver. In the following examples, the invention is based on the tapes produced such counterparts are explained in more detail. The description is based on the statuses that are limited, even after minor work steps. Usual intermediate forming, preferably cold forming, in a single step, such as melting technology, stripping and the like.Improved surface, i.e. low roughness and heating of the slabs, transport processes, high reflectivity, whereby, if necessary and uncoiling processes, cutting, etc., increased corrosion resistance is also required. i ° let,
is enough. example 1

From Landolt - Börnstein, 6th edition, _TT , ",. , _T7,,

IV. Band Technik, Part 2, p. 519, Table I ₅ is used as the production of descaled hot strip

Stahl N the German Normstahl X 22 CrNi 17 be (, »WeiUDand«)

Knows whose target analysis is that of the invention to 15 Made of stainless, ferritic chromium steel, which in the

used steel partially overlaps. For this electric furnace was melted, is descaled

Normstahl, however, apply the usual, technologically broadband with a width of 1250 mm and a thickness of 3.5 mm

conditional nitrogen content. manufactured.

From US Pat. No. 2,750,283 a steel, "..,, _c . ,, ",.,

Group known that apart from 10 to 35% chrome Wahl- *> ^a > Production process according to the state of the art

wisely 0 to 50% nickel, up to 1.5% carbon, al) The crude steel was in the electric arc

up to 5% silicon, up to 20% manganese, up to 10% ° f ^en (melting weight 28 t) melted and in

Molybdenum, up to 10% tungsten, up to 5% vanadium, licher way tapped.

Zirconium, tantalum, niobium and titanium, up to 0.50% a 2) The analysis, according to the regulation

Nitrogen, up to 10% copper, up to 50% cobalt 25 DIN 17,440, steel grade X 8 Cr 17, resulted in the following

and up to 5% aluminum, the remainder iron. Contents (data in percent by weight):

The steel alloy to be used according to the invention

is therefore as falling in this steel range per se ^{c si Mn Cr Nl}

knows. _ 0.064 0.63 0.32 17.20 0.22% '

Regarding the change in the usual alloy _{- 30 J ^ 0} - ^ ^ j Q ₁ Q ₀

composition are in other context q ^ q Q3Q4 q 07 014 0 09 ° /

suggestions have also been made (USA.-Patent- 'j ■ ■ >> ■ 0

2 851 384). This process, incidentally, a 3) This steel became slabs in weight

has not been introduced in technical practice, deviates from 71 shed.

in the intended analysis areas from the previous 35 a 4) The slabs were laid in the usual way Invention and recommends annealing next to preliminary slabs with a thickness of 130 mm at temperatures that are above normal levels and then on a continuous broadband. In addition, this work developed the solution from other street to hot strip with a thickness of 3.5 mm. ^ Tasks to the goal and there is no technically used-rolled and reeled, possible way to solve the pending questions. 40 a 5) The bundles were then in a

In another work proposals are also used and annealed bell-type annealing furnaces. The change in the alloy composition Temzur loading temperature was 840 ⁰ C and the holding time at target Temkanntgeworden (USA. Patent 3,128,211). Even temperature 6 hours, these suggestions aim in a completely different direction. a 6) After cooling, the bundles were initially

There is also a publication about 45 in the "Descaling Line" blasted and renewed ferritic chromium steels in which the influence is twisted. Part of the scale was removed from file; denier anylase variants on the so-called »Um- but a part remained on the surface, changing behavior« is described. In this work with the smallest particles under the influence of being hit the austenite formation at high temperatures the steel shot deeper into the basic substance. and which were pressed out of 5 ° on subsequent cooling.

standing structural components described. There are a 7) Then the tape had to be

there test melts (25 kg melts) are subjected to multiple heating, the have been sought that have been melted in a laboratory furnace in a continuous cycle of several, are. (Mem. Sei. Rev. Metallurg. 59 [1962] p. 571 and successive pickling baths more different 587, 68 [1966], p. 657). 55 composition and temperature. Measure

However, this work does not contain a method for eliminating the intensity of the pickling in the run-through of the problems described. procedure is the »effective immersion length«, the

There are also indications of a change in the over- in this case had to be 40 m, Lent hood annealing temperature (USA patents The strip treated in this way showed the following properties -

992; 2 808 353 and 3139 358), however, in 60ths (average values from beginning, middle and end): this work an increase in the annealing temperature roughness (absolute surface roughness) 24 μ (see Fig. 1). recommended. In addition, this work does not give any clarification of the surface improvement,

Reference to the solution of the above-described ones achieved by the method according to the invention Problems. are those with the help of a surface device

The simultaneous significance of the steel 65 (Perth-O-Meter) used measurement results in the composition and a lowering of the incandescent images reproduced, wherein the Fig. 1, Temperatures that significantly simplify the production of the 3 and 4 of the left column according to the state conventional production, combined with an important technology, while FIGS. 2, 5, 6, 7 and 8

the right column show the values according to the method according to the invention.

Chromium content of the surface layer, determined with the microprobe: 13.6%.

As a result of the various annealing treatments, there was a depletion of chromium on the surface 17.2 minus 13.6 = 3.6% occurred.

b) Method according to the invention

For the same order, another melt was produced and cast into slabs, which were then closed Descaled hot strip ("white strip") were processed.

b 1) Melting in an electric furnace (see a I).

b 2) The analysis showed the following composition:

C.
0.093

Mon
0.06

Si
0.18

N ₂
0.076

Mn
0.85

AI
0.007

Cr
16.10

Cu
0.16

Ni
0.64%

Co
0.037%

b 3) See example a 3).

b 4) See example a 4).

b 5) The hot rolled coils were annealed in the annealing furnace at 750 ⁰ C, the holding time at target temperature was 5 hours.

b 6) Descaling by steel blasting was not necessary and did not take place.

b 7) As a result of the slight scaling of the hot strip a pickling treatment in the usual continuous process was sufficient for descaling [s. a 7)]; could however, the effective diving length can be limited to 25 m.

The tape treated in this way showed the following properties:

Average surface roughness 12 μ (see Fig. 2)

Chromium content in the surface layer 14.9%.

With less roughness, the chromium depletion was only 16.1 minus 14.9 = 1.2%.

The comparison of the manufacturing process according to the conventional type made in this example [Example 1 a)] in contrast to the method according to the invention [Example 1 b)] leads to the following result:

With the new process, a higher quality hot strip can be produced with less effort will. In particular, the cost of annealing the hood is lower, since both the temperature is reduced as well as the glow time could be shortened. This reduces investment and operating costs. as well the effort involved in descaling is lower, as there is no need to go through the jet descaling system can. With the new method, the spreading is better at the same time, i. H. the weight ratio from ready-to-ship, finished white tape to used raw tape, which results in a further reduction in manufacturing costs affects. With the reduced effort, a product of higher quality is achieved because on the one hand the roughness, expressed by the roughness depth, is lower, while on the other hand the chromium depletion is restricted, d. That is, the surface layer which is decisive for the corrosion resistance has a higher chromium content.

Example 2
Production of cold strip

Another bundle of the "white tape" produced in the preceding examples 1 a and 1 b) became cold strip from at the steelmaker's after the interim investigation described above 0.6 mm thick and 1200 mm finished width rolled out. A multi-roll stand was used as the cold rolling mill, Type »Sendzimir« available. The »grinding line« used was equipped with four grinding heads, which are optionally provided with abrasives of different grain sizes for "coarse sanding" and "fine sanding" can be. The facilities for annealing and

ίο Pickling works continuously, ie in a continuous process. A reversing duo was available for the optional "skin pass", ie for the so-called smoothing pass.
In detail, the following operations resulted from the conventional process:

a 1) Cold rolling of the white strip on a Sendzimir stand to a thickness of 1.6 mm,
a 2) pre-grinding in the grinding line,
a 3) Finish grinding in the grinding line.

a 4) intermediate annealing in a continuous furnace at 820 ⁰ C, oven time 4 minutes. This intermediate annealing was necessary because the strip cold-worked from 3.6 to 1.6 mm had already assumed ^{a strength of 95 kp / mm 2.} As is known in specialist circles, smoothing, i.e. elimination of grinding marks, is only guaranteed by further cold rolling with ductile, soft-annealed belt with a strength of about 48 to 55 kp / mm ^2,
a 5) continuous pickling; effective rope length 22 m.

a 6) Cold rolling with a Sendzimir stand to a final thickness of 0.6 mm. Since the beginning of finish rolling The work rolls used became rough after a short time, the rolling process had to be interrupted. A second and finally a third pair of freshly ground, polished work rolls were used.

a 7) final annealing was carried out in a continuous furnace at a temperature of 83O ⁰ C and a furnace time of 80 seconds.

a 8) In the case of final pickling, an effective immersion length of 20 m had to be observed to remove the scale.
Samples from the beginning, middle and end of the strip treated in this way showed the following properties:

When examining the microstructure, random grain growth was found. The surface roughness (absolute peak-to-valley height) was 1.1 μ (see FIG. 3).

A gloss measurement showed a reflectivity of 65%. The chromium content in the near-surface Layer was determined to be 14.8% with the microprobe, i.e. that is, the chromium depletion was still minus 17.2 14.8 = 2.4%.

a 9) One half of the tape was then trained in a manner known per se, d. H. cold deformation subjected to about 1%. This measure further reduced the roughness and the gloss improves.

On the stainless steel strip treated in this way (end product), the absolute surface roughness was 0.7 μ (see Fig. 4), while the gloss measurement showed a reflectivity of 75%.

This cold strip was then turned into automobile hubcaps in a locally separate processing plant processed. In consideration of the very strict acceptance regulations of the vehicle manufacturers For the surface quality of the finished parts it was necessary

109 542/301

Claims (5)

9 10 Bring deep-drawn rolling part in the form for the eye of the beholder. The good surface properties of the The more visible area through the so-called »Schwab cold strip has been preserved to such an extent that one bein «can be improved. Correction of the surface quality by mechanical b) In the further processing of the reworking or polishing according to the invention was not necessary, produced "white tape" (see example 1 b) could the 5 The above examples explain that the erZahl the number of operations can be reduced. Apart from measures according to the invention for the raw strip, too of other simplifications, explained below, which are considerable advantages in the manufacture of cold gens was able to produce rolled strip in particular on the double grinding. While in cold rolling and - as a consequence of this - also on the intermediate operation in a "white annealing" treated according to the invention be waived. io band «first of all work steps 2 to 6 and The individual operations include: at the same time, of course, the corresponding manufacturing b 1) Cold rolling with a multi-roll rolling effort can be omitted, the work to a final thickness of 0.6 mm. In the course of the cold-rolling final annealing according to the invention with lowered temperature The process was carried out twice a pair of freshly sanded, temperature. This would be with a conventional polished work rolls inserted; other sub-15 customarily manufactured tape was not possible because no breaks. in the case of state-of-the-art production in this case b 2) to b 6) could be omitted. b 7) final annealing. The final annealing took place, sufficient recrystallization does not take place. the deviating from the state of the art, at only 760 ° C lower scaling has, in turn, a shorter and with an oven time of 80 seconds. 20 result in a more cost-effective pickling process, b 8) During the continuous pickling treatment, the product, with or without smoothing "Effective diving length" of 12 m required. stich, according to the new procedure in every respect The tape produced in this way showed improved properties. The disturbing rough metallographic examination of a random grain is, as the pictures make clear, on a practical growth; the roughness (absolute roughness depth) is reduced to an insignificant level; the consumer deception average of several samples 0.6 μ (s. F ig. 5), circles particularly important "gloss behavior," ausgedas reflectivity 80%> The chromium content suppressed by the physically determined Reflexionsder surface layer was 15.3 ° / _0, d. This means that the chromium capacity is increased and the reduction in corrosion resistance compared to the overall cross-section is achieved as a result of the physically and in its chemical composition only 16.1 minus 15.3 = 0.8% · 30 chemical composition. b 9) The smoothing pass (skin pass) was carried out as if increased under the surface layer, a 9). For parts that only require minor cold forming In the case of the cold strip produced in this way (which can be thrown for dispatch, the process variant follows End product) resulted in an absolute surface roughness of the example 3 previously unattained properties. At the 0.4 μ (see Fig. 6) and a reflectivity of 35. Comparison of the operations according to the conventional one 86% · Procedure with those of the new procedure will also During the finishing process into hubcaps the reduction in manufacturing costs is evident,
(analogous to Example 2 a) there were no difficulties whatsoever. Post-polishing of the deformed parts is required in the examples described above. H. the hubcaps, was not required because upper 40 issued. Another important aspect is the improvement of the surface quality and gloss to meet the requirements of corrosion resistance. So are z. B. Force of the buyer. vehicle parts subjected to 3 corrosion resistance of stainless steels increased as represented by the -. ,,,, .., "" used for snow combating road salt verHerstellung cold-rolled strip for d _le Preparation of _{45 ursacht wkd The} corrosion attack is particularly moldings _{danQ very} ^^ ^^ _{if on} the relevant Another collar, which, according to example Ib), has a steel part (e.g. hubcap), a covering made of road dirt was procreated, was processed in the same way that was made with salty water. tet as in Example 2 b); it just resulted in soaking. This sustained attack can The following differences: 5 ° -like steel parts that are made in the conventional b 1) Cold rolling to 0.45 mm, produced, lead to rust attack. It is therefore b 7) final annealing 630 C; Furnace time 70 seconds, even the use of the more expensive austenitic, rustproof b 8) Pickling, effective immersion length 8 m. free steels have been proposed and carried out. The roughness of the cold strip was 0.4 μ (see, on the other hand, everyday objects that are made of Fig. 7); the reflectivity was 85% x 55 for the cold strip produced by the new process b 9) The skin pass corresponded to the process - to be produced, improved corrosion properties - step a 9) or b 9) in example 2. th; so are z. B. such automobile hubcaps less On the cold strip that could be shipped, the rough- ed was sensitive to the aforementioned corrosion The speed has dropped to 0.27 μ (see Fig. 8) and the reflective attack by road salt. assets increased to 90%. The chromium content of the 60 The hot- The surface layer was 15.4 ⁰ J ₀ , ie the chrome or cold-rolled strips can otherwise be in Impoverishment amounted to 16.1 minus 15.4 = 0.7% In the further processing of the cold strip in a ratebau), household items etc. are processed, locally separated supplier of the motor vehicle industry _n
were made from the cold strip by punching and processing.
molding moldings made for automobiles. 1. Process for the production of a hot-despite the somewhat higher strength properties and / or cold-finish-rolled strip, from this the parts can be perfectly placed in the desired sheet metal and from it, preferably I 608 cold, formed products made of ferritic chromium steel with high corrosion resistance and smooth surface, the hot strip being subjected to a hood annealing, characterized in that an known steel that consists of 0.05 until 0.15 Vo carbon 0 until 0.50% silicon 0.50 until 3.50% manganese 13th until 18.00% chrome 0.30 until 2.50% nickel 0 until 0.40% molybdenum 0.050 until 0.25% nitrogen 0 until 0.50% copper 0 until 0.15% cobalt 0 until 0.08% aluminum Remainder iron and impurities exists, is used and the hood annealing of the hot strip is carried out in the temperature range from 650 to 780 ^° C., preferably in the range from 700 to 760 ^° C. 2. The method according to claim 1, characterized in that the used, known per se Steels off 0.065 to 0.135% carbon
0 to 0.350 V ₀ silicon 0.60 to 2.000% manganese
13.5 to 16.800% chromium 0.45 to 1.800% nickel 0 to 0.3007 ₀ molybdenum 0.055 to 0.130% nitrogen 0.02 to 0.300% copper 0 to 0.130% cobalt 0 to 0.050% aluminum
Remainder iron and impurities exist. 3. A method for producing a cold finish-rolled strip according to claim 1 or 2, characterized in that characterized in that the strip cold re-rolled after the hood annealing in a manner known per se intermediate and / or final annealing is carried out between 800 and 850 ° C. 4. A process for the preparation of a final cold rolled strip according to claim 1 or 2, characterized in that the kaltnachgewalzte after box annealing band 650-800 ⁰ C, preferably 700 to 800 ⁰ C, intermediate and / or final annealed. 5. A process for the preparation of a final cold rolled strip according to claim 1 or 2, characterized in that the kaltnachgewalzte after box annealing band between 500 and 650 ⁰ C is intermediate / or final annealed and. 1 sheet of COPY drawings