US2261851A - Iron alloy for cutting tools - Google Patents

Description

Patented Nov. 4, 1941 2,261,851 IRON ALLOY FOR CUTTING TOOLS Leo Kliiger. Vienna, Germany, asslgnor to Fcmr Steel Corporation, of

Applicati In No Drawing.

rial No. 238,026. 1937 Lnxemburg on October 31, 1938, se-

Germany November 3,

1 Claim. (Cl. 75126) It has previously been proposed to make cutting tools, drills, reamers, milling and other tools, which must be made of specially hard material, from iron alloys which are capable of being cast and flow easily, the rough casting being substantially in the final shape required. These alloys have a somewhat high carbon content in order to ensure the fluidity necessary for casting; they also contain additions of tungsten, molybdenum and chromium. It has been found,

however, that the behaviour of these steel alloys is such that they cannot be widely used in practice.

The cutting speed of these steels can not be increased up to that of high speed steels because the surface of the object to be machined is then not smooth but becomes wavy to some extent and a subsequent grinding process is necessary. that these alloys must it has also been found be hardened at high temperatures and the parts of the tool which are subjected tothe greatest stress, namely the cutting edges, will not withstand such high temperatures but fuse away. Finally, it has also been found that erosion of the cutting edge takes place at red heat during working, for example during milling.

All these disadvantages are obviated when tools made of alloys in accordance with the present invention are used. In the alloys according to the invention a definite relationship is maintained between chromium on the one hand and the sum of all the other selected alloy additions on the other hand. Particular attention is drawn to the fact that milling cutters and other tools which are made from these alloys can be cast to the finished dimensions, ground andoperated at high cutting speeds, notwithstanding which the machined surface remains quite even and smooth and does not require to be subsequently smoothed or ground as usual.

An'alloy in accordance with the invention may consist for example of 6% chromium, 1% t1mgsten, 1% molybdenum, 1% cobalt, 0.5% manganese. 0.5% vanadium, carbon in an amount up to 1.5%, and the remainder iron. In this alloy the weight of the tungsten, molybdenum, cobalt,

manganese, vanadium, and carbon amounts to substantially 92% of the weight of the chromium when the alloy contains '1.5% carbon.

A feature which is essential if the alloys are to have the properties desired is that the sum of all the metallic and metalloid constituents excluding chromium amounts to or more of the chromium content of the alloy. The parts by weight of the constituents contained in the alloy can therefore be varied, for example, 'in accordance with the following table without departing from the condition stated above and without impairing the usefulness of the alloy for the purpose in question.

Cr W0 Mo .00 Mn Ya Percent Percent Percent Percent Percent Percent 6. 0 .l. 8 0. 6 1. 2 8.0 2.4 p 0.8 1.6 10.0 4.0 0.5 3.0 0. 5 0. 5

In the above table the weight of the alloying elements, other than chromium, ranges from 60% to of the weight of the chromium.

drills and the like can be cast alloys do not contract greatly under heat treatment.

in their final shape. and expand very They also become speeds is ensured; also the cutting edges do not fuse away. A milling cutter made of an alloy in accordance with the invention produces a tent diilers from that given in the examples also fall within the invention provided the relationship between the chromium content and the sum of the remaining metallic or metalloid additions is maintained. I claim:

A steel alloy, tools, containing Mo about 0.5%, Va about 0.5%, the remainder Cr about 10%, W0 about 4%. Co about 3%, Mn about 0.5%, C in an amount up to 1.5%. and Fe.

LEO KLUGER.

alloys flow easily so that milling cutters, I

adapted to be cast, for cutting