US2121415A - Process for the manufacture of sheets, bands, tubes, rods, and the like, and in particular wire - Google Patents

Description

June 1933 A. VOM 'BRAUCKE I PROCESS FOR THE MANUFACTURE OF SHEETS, BANDS, TUBES, RODS, AND THE LIKE, AND IN PARTICULAR WIRE Fi1ed Sept. 6, 1935 1 w) ga rban INVENTOR ADOLF YOM BRAUCKE,

ATTORNEY.

Patented June 21, 1938 PnooEss FOR THE MANUFACTURE OF SHEETS, BANDS, TUBESRODS, AND THE .LIKE, AND IN PARTICULAR WIRE Adolf vom Braucke, Berge, Germany Application September 6, 1935, Serial No. 39,496

In Germany September 7, 1934 3 Claims.

In the manufacture of steel wire the process starts as a rule from wire made by rolling which is then drawn in one or more steps to the desired diameter. As, in the drawing, the danger 5 of an excessive increase in hardness due to cold working and of resultant breaking of the wire may arise, the piece to be drawn is sometimes heat treated before the drawing and also between the various drawing'sta'ges. As regards this heat treatment,- the' so-called "patenting of thewire is generally eiiected, that is to say, the wire is heated to'somewhat above the Ac; point which, according to the carbon content, lies at temperatures between 900 C. and about 700 C., and is 5 finally quenched in a lead bath to temperaturesv of about 500 C. This heat treatment gives it a sorbitic structure with a fine grain. Owing to' the fact that the heating is carried out for onlyw a short time at or above the A03 point, the socalled normalizing range is arrived at in which the, material assumes a fine grained structure.

Extensive research has now shown that the fine initial structure of wire which is to be drawn or rolled to a smaller cross-section has an unfavorable efiect on the drawing process and .the properties of the material, because the various grains can only be stretched to a well de-- fined limit of length before they will break.

It has been found by my esperiments that the long fibred wire has the best properties. Such a long fibred final structure can however be obtained only when starting from large grains. The coarse grained starting materialis capable of the greatest decrease in cross-sectional area, that is to say, extensive cold working and thus, in addition toother advantages, makes a considerable economy in operation possible.

The invention relates to a process of heat treatment which will givethe coarsest readily o attainable grain. formation in the material.

In the iron-carbon diagram illustrated in the drawing, the temperature ranges or zones characterizing the new process are designated I, II, and III. 7 v V For obtaining as coarse a structure as possible, the wire, according to its carbon content and it's cross-section. is, in accordance with the invention, quickly brought to a temperature substantially'above the Ac: point (800 C .-l300 0.).

At this temperature, the: whole carbon content is'in solid solution and the material acquires a coarse structure; From the range l,.th'e wire is then quenched to a temperature within the temperature range II which, according to the carbon content, is from 720i .C.-1050 C. and finally is quenched in a lead, air, salt, oil, blubber, petroleum, tallow, acid or alkaline bath to a temperature within the range 111 (0 C.-720 C.) and, if desired, down to room temperature. The temperature to be reached in the range I of the 5 iron-carbon diagram depends upon the quenching temperature in range II. -The temperature is always determined so that a structure is ob tained which is as coarse grained as possible.

It has also been found that it is advantageous to heat up to the high temperature as quickly as possible. This appears to be due to the fact that thereby complete solution 01 the carbide is obtained more quickly than would otherwise be the case. The new process has the advantage 15 that no undissolved lamellae of cementite from a previous heat treatment are left in the material, so that during the quenching (range III of the iron-carbon diagram) no cementite can agglomerate with. cementite lamellae remaining from a previous treatment. established that' with a heat jtreatment in ac-. cordance with the invention, the distribution of any foreign substances along the grain boundaries is more favorable than with therpreviously as usual treatment. By rapid heating to the high temperature, there is no time for this substance to separate out at the new grain boundaries but it separates out in a harmless intracrystallinear fashion.

Summarizing, extraordinary advantages have been revealed in the practice of the new process. One of the most important is that wire can becold drawn to a ,much greater extent with the same ultimate tensile strength and the number of heat treatments can be reduced to a minimum. The number of torsions, alternating torsions and bends .under test increased by approximately by the use of the process in accordance with the invention.

The new heat treatment process is not confined to the manufacture of wire. It is most useful wherever the material is to be cold worked as for example, in the manufacture of sheet metal, tubes, bands, rods and the like.

treated asjnow proposed is coarse grained and, 55

It has also been 20 as I have found that a material having a coarse structure can be drawn out to a much greater ex-.

' tent with the same ultimate tensile strength, it

materials ensures a complete destruction of the cementite. I

The heat treatment will take place before the cold working of the material and, when this is carried out in stages it can be repeated a number of times. The finished cold worked objects can, as in prior practice, be subjected to a temperature in the a or ranges. In this way, where it is required for the use to which it is to be put, its structure can be made finer. It the objects are to be drawn or rolled to a special hardness, the drawing or rolling process can be interrupted at a correspondingly early stage according to the desired hardness, so that afterthe necessary consequent cold working to the final size, the desired hardening will also be attained simultaneously therewith.

The new process is suitable in particular for iron alloys but it can also be used for the manufacture of cold worked articles of other metals.

I claim:-

1. In the manufacture of sheets, bands, tubes, rods, wire and the like by cold working of iron or steel alloys, the step of treating the material to preparatory to its cold working, for the purpose of providing it with a coarse-grained structure,

which step comprises, rapidly heating the material to a temperature depending upon its carbon content and lying .within zone I (800 to 1300 0.), quenching the material to a temperature within zone II (720 to 1050 C.), holding the material at said latter temperature for such time as is required toattain a temperature within zone II, and quenchingsaid cooled material to a temperature within zone III (0 to 720 C.)

2. A process for manufacturing sheets, bands, tubes, rods, wire and the like, which comprises subjecting the material to cold working in a number of stages and heattreating said material both before and after at least one of said stages, said heat treatment comprising rapidly heating the material to a temperature depending upon its carbon content and lying within zone I (800 to a 1300" C.), quenching the material to a temperature within zone II (720 to 1050 0.), holding the material at said latter temperature for such time as is required to attain a temperature within zone II, and quenching said cooled material to a temperature within zone/III (0 to 720 C.).-

3. A process for manufacturing sheets, bands, tubes, rods, wire and the like, which comprises rapidly heating the' material to. a temperature depending upon its carbon content and, lying within zone I (800 to 1300 0.), quenching the material toa temperature within zone II (720 to 1050 C.), holding the material at said lat- 7 ter temperature for such time as is required t6 attain a temperature within zone II, and quenching said cooled material to a temperature within zone III (0 to 720 C.), cold working said heat treated material, heating said cold worked material to a temperature below the AC1 cooling said material in air.

ADOLF vetama point and 1

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