US221281A - Improvement in the manufacture of chrome-steel - Google Patents

Description

whereas by my process there is 11 UNITED STATES RICHARD BROWN, 0F .AYR, COUNTY OF AYE, SCOTLAND.

IMPROVEMENT. IN THE' MANUFAOTUREOF CH ROM E-STEEL,

Specification forming part of Letters Patent NO. 221381, dated Novombcr'd, 1879 application filed May 9, 1879.

chromium with iron'in a better and more-satlsfactory mannerthan has been hitherto ac complished, in order to obtain what are known as chrome-steels, or steel-like metals of improved qualities Chrome-steel may by my invention be made either of the hard or mild variety or of an intermediate quality by suitably proportiouing the substance I employ for effecting the improvements. My invention has also the advantage that castings of the steel made by it are 'very solid and comparatively free fromthe blow-holes which give so much' trouble with castings of steel made by the Bessemer or Siemens-Martin or other processes.

, My invention consists in combining the chroimium with the iron or steel by employing one or more of certain compounds of chromium,

hereinafter specified,'these compounds having theimportant practical advantage over what hasbeen previously used of not only being a convenient, expeditious, certain, and effective means of introducing the chromium into the iron orsteel, but 'also of-elimiuatiug impuri ties or injurious ingredients to a greater or less extent, and of neutralizing the injurious I actionof impurities or utilizing such iugredt cuts as are not eliminated. Analyses of so-called chrome-steel as made 7 by'i'pro'cess'es hitherto-used have showii that such processes have been extremely uncertain, and in many cases altogether ineffective in. combining 'ifi'fie'ct ing the desired combination.

I The compounds to be used in carrying out lniyiinvention are bichromates of? potash and soda and chromates of potash, soda, lime, and magnesia. Of these compounds I/b'elieve the bichromates to be the most advantageous, and

-I' prefer to employ the bich romate of potash,

especially when the metal operated on-contains phosphorus.

' ln"curryin'g out mysaid invention the ironchromium with the iron or steel,

or metal to be operated on,and which may, if

by being blown in, in powder, by a blast applied as .in the Bessemer process; or it may be simply mixed into the molten metal. It

should, however, in all cases be thoroughly intermixed, and the temperature should be such asto keep the metal sufficiently fluid for the mixing to be effectively performed. The powdered material may be introducedintothe blast-pipe of the Bessemer converter by means of a small hopper communicating with the pipe bya descending passage fltted'with. two

valves, the material belngti'rst admitted into the space between the valves, and, after closin g the upper valve allowed' to descend gradually by opening the lower valve; or the material may be introduced into the metal from v the mouth of the converter, the blast-being stopped during the introduction, and. afterward renewed for a few minutes, in order to effect a thorough mixture. When adding the material in areverberatory furnace or cruci-' his, or other vessel, it may be iu powder or in small pieces put up in several paper hagsor other wrappers, which will afl'ord a slight pro tection while .it is being introduced, and while introducing the material the slag must be pushed aside by means of an iron rod or other instrument When the metal is in a erucir blethe cover must be kept more or less open for a short time after adding the material, in

order to'allow of the escape of gas,.and the crucible shouldnbe. kept in the furnace for about fifteen .niinutes after closing the cover. The selection of bichrom'ate of potash or other compouhdor compounds and the pro portion thereof to be employed will vary in each case with the particular qualities of steeldesired, audalso with the kind and propor- ,tion of impurities operated on.

, When-the iron or metal to be operated on 4 contains'much carbon the excess of carbon PATENT "OFFICE,

presentin the iron or metal should be eliminated by means of the Bessemer or other suitable process before treating the metal according to my presentinvention. Taking, for example,- cast-irou containing .75 per cent-um of phosphorus and a variable quantity of carbon, the proportion of carbon should be reduced to about .2 per centum, and about I .75 per centum of bichromate of potash should then be mixed with the melted metal.

This

will yield a ductile steel. A larger proportion of bichroma-te of potash will give a harder nor imparts undesirable qualities, but, on the contrary, improves the metal, particularly by rendering it capable ot' beingcast in every solid condition, and free, or nearly so,.from

cavities or blon -ho1es. Witha larger proportion of phosphorus present in the metal than that given in the above example, the steel, will be harder, other things remaining the same.

When the proportion of phosphorus is less than that given .in: the example a larger proportion of carbon may be retained; and similar results may be obtained with a smaller proportion of bichromate of potash. I

After the iron or metal has been'treated as hereinbefore: described, spiegeleiseu or ferromanganese or peroxide of manganese may be added toit; hnt inmany cases this will not be necessary.

I claim as my invention- In the manufactnre'ot' chrome-steel, the

method of facilitating the introduction of the chromium and of improving the quality of the steel produced-that is to say, by mixing with the molten bath chromates or bichromates, such as hichromate of potash or soda or chromate of potash, soda, lime, or magnesia, substantially in the manner described-.-

RIGHARD BROWN Witnesses:

EDMUND Hour, LOCK Moons.