US1625524A - Manufacture of steel sheets - Google Patents

Description

Patented Apr. 19, 1927.

UNITED STATES PATENT OFFICE.

.WILLIAM E. C AUGHERTY F NATRONA,

PENNSYIJFANIA, 'A-SSIGNOR, IBY mnsnn AS- SIGNMENTS, TO- ALLEGHENY STEEL COMIANY, OI BRACKENRIDGE, PENNSYL- VANIA, A CORPORATION OF PENNSYLVANIA.

MANUFACTURE OF STEEL SHEETS.

N'o Drawing.

This inventionrelates to'the manufacture of steel sheets and particularly to the manufactureofsteel sheets suitable for use where difiicult stamping or drawing operations are necessary.

In the ordinary manufacture of such sheets, the ingot is rolled in a standard three high mill into a sheet bar which is eutinto suitable lengths for completion into sheets.

The length of the cut bars becomes the width of the sheets and because ofthis, the rolling of the sheets takes place atright angles to the direction of rolling of the bars. This cross rolling, to some extent, causes a refinement of thegrain structure of the sheets. This refinement, however, is only relative,

because the rolling at the sheet mill is done at low temperatures and therefore the elongation of thegrain is still pronounced.

employed in 'rollin this class of sheets and the methodutilize depends on the quality of surface desired. .One method is the socalled, tight rolling method and the other, the loose rolling method.

In the tight rolling method,-the bars are roughed down on the roughing mill, matched or paired, depending on the gauge and size, reheated and finished to length 'on a finishing mill. In this method, the sheets are always'stuck together so that the rolling operation is yirtua] y the same as though the combined sheets existed as one plate. The

scale elongates'fairly uniformly with the elongation of the sheets and; a fairly satisfactory surface can ordinarily be obtained. It frequently happens, however, that -isolated areas of surface scale become detached and cause defective spots on the sheet and in opening the sheets after shearing, it frequently happens that this scale. does not spread evenly over the surface ofadjacent s eets, and causes a grainy 'or. wood-like surface.

he loose rolling method was evolved in order to overcome the defects in the tight rolling method. Inth'e loose rolling method, the sheets are roughed down to approxi- "matel one-half their final length. They are t en pickled to remove the scale and dipped in an emulsion of charcoal and water.

A coated sheet is then sandwiched between two uncoated sheets and the pack is heated to a relatively low teinperature and finished Application filed. June 18,

There are two distinct methods at present have the advantages' pf both the present 'tomary in the tight rolling method,.thc

structure of the steel is very much distorted with the result that it is very diflicult to refine the steel by subsequent annealing. The smooth glassy surface of the loosely rolled sheets adds to the difiiculty of final annealing, since after the sheets are pickled, they have a great tendency to stick together when annealed in bulk as in'commercial box annealing. In order to avoid this sticking, it is customary to anneal immediately after rolling; the original scale on the sheet serves to prevent the sheets 1 from sticking. This annealing is done at a high temperature in order to get as much refinement as possible. Since it is necessary to picklev the scale ofl? after annealing it becomes necessary to give the sheets a second anneal to remove the hydrogen which has been absorbed from the picklin operation.

An 0 ject of this invention is to provide a method of rolling s'teel sheets which will tight and loose rolling methods without the disadvantages of either.

'A further object is to provide a'relatively cheap method of rolling high grade steel sheets suitable for difficult stamping and drawing operations. These, as well as other objects which will readily appear to those skilled in this particular art," I attain by means of the method described in the spec'- ification forming part of this a plication.

In carrying out my improve method, the sheets are roughed down to approximately one-half their finished lengt They are then singly annealed in a standard blueanneal urnac operated continuously at a temperature sufliclently high to completely transform the rain or normalize the structure. After this anneal, the sheets are pickled and then coated by being dipped in an emulsion of charcoal and water. They are then matched or paired and raised to a relatively low rolling temperature and rolled to length.

The final rolling while at a relatively low temperature does not distort the structure which has been produced by the annealing operation, since the sheets are approxin'iately one-half the finished length at the commencemcnt of the final rolling operation, the work necessary being relatively slight.

If cold rolling is desired, this can be interjected either before pickling or after pickling.

I have found that the structure produced by this method is much superior to that obtained by either the present tight or loose rolling method.

By this method it is possible to considerably chcapon the production of high grade sheets. Instead of rolling the ingot into a bar and roughing the bar down in the sheet mill with high priced labor as is now customary, I roll the ingot into slabs in a slab mill and convert these slabs into blue-annealed plates or sheets of large size which can be annealed and subsequently sheared to sizes suitable for the sheet mill finishing operations. These sheared plates or sheets, after being pickled, become the raw stock for the sheet mill operation, and, since the final rolling is of relatively short duration, it is obvious that the roduction of the sheet mill is considerab y increased. The crews are reduced for the reason that it is not necessary to heat and rough down the bars, and since this labor is considerably higher than that employed in rolling the blue-annealed plates or sheets, I accomplish a considerable reduction in cost.

From the above, it will be seen that I carry on the final rolling operation only, in the sheet mill. In all other steps I employ the standard commercial operations used in the production of blue-annealed sheets.

By way of example: If it is desired to produce a 20 gauge sheet 36"XlOO long.

produce in the blue annealed plate and sheet department a blue annealed and pickled sheet 36"1-160 long of a gauge suflicient to produce a 20 gauge sheet when rolled to 120". These sheets I furnish to the sheet mill department where they are dipped in an emulsion of charcoal and water, matched or paired, heated to a relatively low temperature and rolled to length in one operation.

In this method, the ingot is bloomed down into slabs by rolling in one direction. The slabs are sheared so that the length of the sheared pieces" becomes the Width of the blue annealed plate or sheet; the second operation being at right angles to the first operation. After the slab has been converted into a blue annealed plate or sheet, it is sheared to size for the sheet mill opera tion in such manner that the final rolling is at right angles to the second rolling operation. or in the same direction as the first.

inaasei I find that this has a tendency to benefieially influence the size of the grain and materially toughen the final product.

Having thus described my invention, What I claim is:

1 The method, which consists in roughing down steel sheets to approximately onehalf their finished length, in annealing the roughed down sheets at a temperature sufficiently high to transform the grain structure thereof, in pickling said annealed sheets, in matching or pairing the roughed down sheets, in rolling the paired or matched sheets to length, in pickling the sheets after rolling and then in annealing the same.

2. The method, which consists in roughing down steel sheets to approximately one-half their finished length, in annealing the roughed down sheets at a temperature sulficiently high to normalize the grain structure thereof, in pickling said annealed sheets, in matching or pairing the roughed down sheets, in loose rolling the paired or matched sheets to length, in pickling the sheets after loose rolling and then in box annealing the same.

3. The method, which consists in roughing down steel sheets to approximately one-half their finished length, in singly annealing the roughed down-sheets at a temperature sufiiciently high to normalize the grain structure thereof, in pickling said annealed sheets, in matching or pairing the roughed down sheets after preparing the same to prevent sticking during rolling, in rolling the paired or matched and treated sheets to length, in pickling the sheets after rolling and then in box annealing the same.

4. The method, which consists in roughing down steel sheets to approximately onehalf their finished length, in annealing the roughed down sheets at a temperature sufficiently high to normalize the grain structure thereof, in pickling said annealed sheets, in matching or pairing the roughed down sheets, in loose rolling the paired or matched sheets to length, in pickling the loose rolled sheets, in cold rolling the sheets either before or after said second pickling and then in annealing the same.

5. The method, which consists in roughing down steel sheets to approximately onehalf their finished length, in singly annealing the roughed down sheets at a temperature sufliciently high to transform the grain structure thereof, in pickling said annealed sheets, in loose rolling the paired or matched sheets to length, in pickling the loose rolled sheets, in cold rolling the sheets either before or after said second pickling and then in box annealing the sheets.

In testimony whereof, I have hereunto subscribed my name this 12th dayof June,

WILLIAM E. GAUGHERTY.