US2392821A

US2392821A - Metal-working tool

Info

Publication number: US2392821A
Application number: US519323A
Authority: US
Inventors: Malcolm G Kreag
Original assignee: HAYNES SELLITE Co
Current assignee: HAYNES SELLITE Co
Priority date: 1944-01-22
Filing date: 1944-01-22
Publication date: 1946-01-15
Anticipated expiration: 1963-01-15

Description

Jan. 15, 1946. a E 2,392,821

X METAL WORKING TOOL Filed Jan. 22, 1944 INVENTOR MaZwZm 6110609 ATTOR Y Patented Jan. 15, 1946 METAL-WORKING TOOL Malcolm G. Kreag, Chicago, Ill., assignor to Haynes Sellite Company, a corporation of Indiana Application January 22, 1944, Serial No. 519,323

6 Claims.

This invention relates to metal-working tools,

and refers more particularly to tools of the type used in working or deforming hot metal, for example piercing points, hot-forming dies and the like. For conciseness the invention will be described with particular reference to metal-piercing tools. a In the manufacture of seamless steel tubing and tubular articles such as shells and the like, a hole is formed in a hot steel billet by forcing a piercing point into the billet, usually along the central longitudinal axis of the billet. The temperature of the billet is high, and the pressure required to force the piercing point through the hot metal is heavy. The piercing point is thus subjected to extremely rigorous conditions, and its life is quite short, failure usually occurring because of severe wear or cracking.

Attempts to provide piercing points having reasonably long life in service have been made but have generally been unsuccessful. One proposal, that piercing points be hard-faced with the well known wear-resisting cobalt-chromiumtungsten alloys generally used for hard-facing articles subjected to severe conditions of wear, proved especially disappointing, points hard-faced with these alloys failing after a short time by cracking and partial loss of the surface layer of alloy.

It is the principal object of this inventionto provide metal working tools of the type used in working or deforming hot metal and subjected to pressure, such as piercing points, which have a longer life in service than those tools heretofore known and used. g

This object is achieved by the invention which comprises a metal-working tool having a surface composed of a nickel-base alloy containing molybdenum and chromium and is based on the discovery that a tool having such a surface has a life several times longer than the life of other tools used in the same service. This discovery is surprising because the alloy used, developed and long used for resistance to corrosion by acids, has never been considered as having the properties required of wear-resistant materials.

In the accompanying drawing the single figure is an elevational view of a specific type of tool embodying the invention, part being broken away.

Although the tool of the invention may be composed wholly of the nickel-base alloy, for reasons of economy it is preferred that the body of the tool be composed of a cheaper metal and that a layer of the alloy be deposited on the wearing surfaces of the tool, suitably by welding. The

single figure of the drawing illustrates the application of the invention to a piercing point P. The

body of the point P is composed of steel, and its wearing surfaces are protected by a layer of a nickel-molybdenum alloy deposited thereon.

The alloy surface of the tool of the invention is composed of a nickel-base alloy containing 5% to 25% molybdenum, 10% to 30% chromium, about 0.1% to 1.5% carbon, the remainder prin cipally nickel. The alloy may, and preferably does, contain up to about 10% tungsten, and iron may be present as a diluent up to about 35% of the alloy, but the nickel content should exceed 30%. A composition that has given excellent results. is 15% t 18% molybdenum, 13% to 16% chromium. 4% to 6% tungsten, 5% to 8% iron, 0.1% to 0.2% carbon, and the remainder nickel. The nickel content is most desirably at least and between about 55% and For most purposes the molybdenum content should be at least 10%, the chromium content'not exceeding about 20% of the alloy.

In manufacturing the tool of the invention a tool body is preferably made of a plain carbon or low alloy tool steel, and protective layers of the nickel-base alloy are formed on the wearing surfaces of the tool by fusion-deposition welding using either oxy-acetylene or electric welding methods. A preferred method of forming the protective layers is metallic arc welding. Only a relatively thin layer of the alloy need be applied. In welding, a welding rod having a composition within the ranges defined above is used. The deposit produced from the welding rod may differ somewhat in composition from the composition of the rod due to dilution of the weld metal with base metal, but care should be taken to avoid un necessary dilution of the deposited weld metal. A

The weld-deposited metal is usually machined or ground to desired dimensions.

Tests of the tool of the invention have proved it to have several times the life of other tools used in the same service. As a specific illustration both of its serviceability and of its construction, the following example is given.

A water-cooled piercing point 3 /6 inches in diameter and 25 inches long composed of a steel recommended for use in hot working metals was provided with a protective layer of a nickel-base alloy deposited by metallic arc welding from a welding electrode composed of a nickel-base alloy having a composition within the preferred ranges above defined. The pointed end of the tool was covered with a protective layer for a distance of 8 inches from its tip, the layer being about I;

inch thick except at the tip where a deposit about inch thick was formed. The tool so prepared was then used for piercing shells in accordance with standard commercial practice. After the tool had been used to pierce 420 shells, it was examined and found to be still usable without repair whereas substantially identical tools notprovided with a protective layer were badly worn after piercing only 80 shells.

From this example it is evident that tools having surfaces composed of the nickel-molybdenumchromium alloy described have several times the life of similar tools having unprotected surfaces.

The particular alloy used in the invention has been known and widely used for many years in applications where advantage is taken of its excellent resistance to corrosion. However, because of its relative softness and low malleability and ductility and because it is workable only with difficulty it has never been advocated for use as a wear-resistant material. That it acts so well as a protective layer in the extreme service encountered by the tools of the invention, conditions so severe that the commonly-used special wear-resistant alloys fail, is most surprising.

Although specific details of construction of a specific tool have been given herein, such details are for illustration merely and the invention is not limited either to such details or to specific types of tools, but is generally applicable to tools used for working hot metal while the tools are subjected to pressure.

I claim:

1. A metal-working tool having a wearing surface composed of a nickel-base alloy containing 5% to 25% molybdenum, to 30% chromium, the remainder principally nickel, the nickel content being about 55% to 60%.

2. A metal-working tool having a wearing surface composed of a nickel-base alloy containing 10% to 25% molybdenum, 10% to 30% chromium, an efiective amount up to 10% tungsten, 0.1% to 1.5% carbon, the remainder substantially all nickel and iron, the nickel content being more than 30% and iron being present as a diluent in an amount up to 35%.

3. A metal-working tool at least the wearing surfaces of which are composed of an alloy containing 15% to 18% molybdenum, 13% to 16% chromium, 5% to 8% iron, 4% to 6% tungsten, and 0.1% to 0.2% carbon, the remainder substantially all nickel, the nickel content being about to of the alloy.

4. A tool for deforming hot metal, said tool having a steel body portion and a protective layer, on at least its wearing surfaces, of an alloy containing 15% to 18% molybdenum, 13% to 16% chromium, 5% to 8% iron, 4% to 6% tungsten, and'0.l% to 0.2% carbon, the remainder substantially all nickel, the nickel content being about 55% to 60% of the alloy. 4

5. A tool for deforming hot metal, said tool having a wearing surface composed of anickelbase alloy containing 5% to 25% molybdenum, 10% to 30% chromium, the remainder substantially all nickel.

6. A tool for deforming hot metal, said tool having a steel body portion and a protective layer, on at least its wearing surface, of an alloy containing 10% to 25% molybdenum, 10% to 30% chromium, an effective amount up to 10% tungsten, 0.1% to 1.5% carbon, the remainder sub stantially all nickel and iron, the nickel content being more than 30% and iron being present as a diluent in an amount up to 35% MALCOLM G. KREAG.