US2331899A - Piercing die and alloy - Google Patents

Description

Patented Oct. 19, 1943 PIERCING DIE AND ALLOY William F. Finkl, Chicago, Ill., assignor to A.

Finkl & Sons Company, Chicago, 111., a corporation of Illinois No Drawing. Application March 25, 1942, r Serial No. 436,183

4 Claims. (Cl. 75126) This invention r'elatefs'to improvements in steel alloys which are adapted for use in piercing dies used with hot work dies, and particularly for punches, plungers, inserts and plugs or similar die members of relatively small section made of .such alloy, and used in'hot work forging processes under high temperature conditions.

The principal object of'the invention is to pro-, ducea steel alloy die part combining the special characteristics which have been found to be essential to theuses 'above .set forth, including facility and economy of manufacture, and in particular the capability of holding its working hardness at extremely high. temperatures and having a greater resistance to breakage than other alloys previously used for similar purposes.

The improved alloy has been developed to overcome the difficulties of breakage and excessive wear which have been encountered with punches and plungers and similar small-sectioned die parts used with hot work dies. Such die parts are subjected to the most rigorous and exacting conditions because of the extreme variations in temperatures encountered. These small-sectioned die parts must remain in contact with the work at extremely high temperatures for relatively long periods of time, and are usually cooled as by water between uccessive operations.

Several types of steel alloys have heretofore been employed for the particular purposes above mentioned, of which tungsten-bearing alloys are especially notable. It has been found, however, that none of these prior alloy steels arewholly satisfactory since the small-sectioned die parts such as punches, plungers, inserts andthe like are usually the first parts to break or: show wear in dies of this general character. Moreover, such -alloy teels, particularly those containing tungsten, have been "found relatively costly to manufacture, and the virtues of tungsten itself as an" alloying element are more than oifset by an undesirable brittleness after working a short time at relatively high temperatures.

' In carrying out my present invention for the particular purposes above indicated, I utilize molybdenum, chromium, silicon and manganese, all confined within relatively narrow ranges. The preferred ranges of the principal alloying elements of this special steel are as follows:

Per cent Carbon .25 to .35 Molybdenum 2.00 to 2.50 Chromium 4.50 to 5.00 Silicon .80 to 1.00 .20 to .40

Manganese Other elements of a more or less residual char- As an example of a steel alloy made in accordance with my present invention, the following anyalysis may be cited:

Per cent Carbon .30 Molybdenum 2.00 Chromium 5.00

Silicon 1.00 Manganese .35

It will be observed from the above analysis that the carbon content is relatively low (.25 to .35) as compared with steelalloys heretofore generally employed for hot die work, whereas both the molybdenum and chromium contents are rela-- tively high as compared with molybdenum and chromium alloys such as broadly disclosed in my prior Patent No. 1,464,174. I find that the addition of a relatively substantial fraction of silicon (.80 to 1.00%) also adds to the desired wearresisting propertie at the high temperatures of the steels these die parts are used to form.

The special characteristics essential for superior performance in punches, plungers, inserts, plugs and similar small-sectioned die parts, particularly those used for piercing in extrudin punches and for plungers on upsettingv machines, can be obtained to a high degree by limiting the percentages of the several alloying elements within the narrowranges specified for each. Such small-sectioned die parts can be initially manufactured and handled for heat treatment and machined much more economically and safely than tungsten-bearing and similar special alloys heretofore employed for like purposes. Die parts made of my alloy are capable of holding their hardness at extremely high temperatures and can withstand water cooling during the time they are operated, with much less likelihood of breakage.

l have found that in practice under most severe shown an average production greatly in excess of acter such as nickel may'also be present in small I fractions, as is often the case in special alloy steels of this class.

that obtained from dies having similar parts made of special tungsten-bearing alloy of the kind heretofore generally employed for this special purpose.

I claim as my invention:

1. A steel alloy which comprises as its alloying elements carbon ranging from .25 to 35%, molybdenum from 2.00 to 2.50%, chromium from 4.50 to 5.00%, silicon from .80 to.1.00%, manganese from .20 to .40%, and the balance substantially all iron.

2. A steel alloy which comprises as its alloying elements carbon approximately 30%, molybdenum approximately 2.00%, chromium approximately 5.00%, silicon approximately 1.00%, manganese approximately 35%, and the balance substantially all iron.

3. A piercing die for hot work forging made of a steel alloy which comprises as its alloying el e v ments carbon ranging from .2 5 to'.35%,molyb-- denum from 2.00 to 2.50%; chromium 1rom 4.50"- to 5.00% silicon irom'.80 to 1.00%, manganese? from .20 to .40%, all iron.

4. A piercing .di

and the halance substantially v e m not work forzin inade stantiallyallirpn. r