US2185618A - High-speed steel - Google Patents

Description

Patented Jena, 1940 UNITED STATES PATENT OFFICE Firth, Pittsburgh,

Pennsylvania Pl assignors to Firth- Sterling Steel Company,

a corporation or No Drawing, Application Jnne13, 1939, Serial No. 278,902

6 Claims.

This invention relates to high-speed steel of molybdenum type. 1 v

Inappiication for Letters Patent, filedJanuary 21,1939, Serial No..252,2l4, we have disclosed the discovery that boron may advantageously be included in the mix for steel of this type. It is our discovery that, boron being presentin an amount that; in the twenty examples there given, ranges from 0.10 to'O.91% of the iron content, chromium may be entirely eliminated; and that, if chromium be eliminated, or if (being present) it is present in quantity not exceeding 1.50% of the iron content, a steelis produced that is free of any tendency to deteriorate in heat treatment, and a steel that possesses the desirable qualities characteristic of the type.

Our present invention relates to the same subject-matter and, more specifically, to the inclusion in the mix'of copper, with or without VIII nickel also.

In accordance with this invention, an alloy may contain the following elements within the percentages given (the percentages being relative to the iron content):

Percent Carbon .30- 1.30 Silicon ,05-. 1,00 Manganese .10- 1.00 Vana .25- 3.50

Molybdenum 5.00-12.00 Copper .10- 5.00 Bor .05- 1.00

Percent Car .28- 1.04 Sih .05- .80 Manganese -1. .09- .80 Vana .24- 2.80 Molybdenum 4.72- 9.61 Copper .09- 4.01 Bor .05- .80 Iron 94.47-80.12

In addition to copper the alloy may contain (and advantageously contain) nickel, in an amount ranging upward to 3% 01 the iron content.

The vanadium content should be from one to. three and one half times the size of the carbon content. 5 Several varieties or specific examples of copper types of alloy compositions falling within the above given ranges of percentages for the various ingredients, arranged in the order of their carbon content, are as follows: I 10 No. C Si Mn Or Va Mo Cu Ni B The remainder of the compositions tabulated 20 above will be understood to be substantially 01' iron, together with such other alloying elements and impurities as are sometimes found in this type of alloy compositions. 25

Silicon and manganese in small quantities are inevitable ingredients of the mix, and they have their recognized values. Their presence in small quantities may be taken for granted. It is the other components named that give character to so the particular steels, and to these other ingredicuts the claims are directed. The silicon and manganese and other elements adventitiously present do not disturb the essential composition.

The above examples all contain copper. Some 35 contain copper and nickel, also. Their hardening temperatures rangefrom about 1700 F. to 2300 F. The range of drawing temperatures, at which secondary hardness is developed, is from 800 F. to 1200 F. Vanadium has the effect 4 of raising the drawing temperature and toughening the steel.

It has been found that the presence of copper in these steels stabilizes the molybdenum, and prevents its volatilization; it also retards the forma- 5 tion of craters that tend to occur back of the cutting edge. Copper also lowers the forging temperature.

It appears'from examination oitools after use, that the addition of copper to a high-speed steel so containing boron (and in which the chromium content is less than 1.50% of the iron content) has eflect in a particularly low galling property under the chip, as shown by the smooth condition of the edge of the tool after cutting.

In the above table Example No. I has a low carbon content, and is useful in the field of steels in which strength and toughness are of greater importance than cutting quality.

Examples Nos. I and 11 represent steels useful in die work, where the maximum amount of toughness is desirable, together with high resistance to deformation under severe loads at elevated temperature.

Examples Nos. III-VIII: Yathe tools made from these steels, when compared with lathe tools of the 184-1 high-speed steel, had a performance from twenty to thirty percent better.

In the foregoing table percentages are given with relation to the iron content. Taking the essential elements (as specified above) of these specimen steels-carbon, vanadium,molybdenum,

copper, boron, and ironand reducing all to percentages of the whole, we have- 0 Va Mo Cu B Fe 42 5. 72 l. 51 39 91. 57 78 7. 44 2. 66 33 88. 29 98 7. 27 2. 38 19 88. 60 l. 37 8. 74 3. 03 22 86. 00 1. 62 8. 33 2. 44 14 86. 67 2. 10 7. ll 1. B2 17 88. 07 2. 23 6. 80 3. 28 12 86. 64 2. 82 7. 28 2. 26 08 86. 50

We claim as our invention:

1. A high-speed steel free of chromium inexcess of 1.50% of the iron content, and of substantially the following composition: carbon,

0.28-1.04%; vanadium, 0.24-2.80%; molybdenum, 4.72-9.61%; copper, 0.09-4.01'%; boron, 0.05- 0.80%; and iron, 94.47-80.12%.

2. A high-speed steel free of chromium in excess of 1.50% of the iron'content, and of substantially the following composition: carbon, 0.37-1.06%; vanadium, 0.42-2.82%; molybdenum, 5.72-8.'74%; copper, 1.51-3.28%; boron, 0.08- 0.39%; and iron, 86-91.57%.

3. A high-speed steel free of chromium in excess of 1.50% of the iron content, and of substantially the following composition: .carbon,

0.58-1.06%-; vanadium, 0.98-2.82%; molybdenum,

6.804314%; copper, 1.82-3.28%; boron, 0.08-

0.22%; and iron, 86-88.60%.

4. A high-speed steel free of chromium in excess of 1.50% of the iron content, and of substantially the following composition: carbon, 0.58%; vanadium, 0.98%; molybdenum, 7.27%; copper, 2.38%; boron, 0.19% and iron, 88.60%.

5. A high-speed steel free of chromium in excess of 1.50% of the iron content, and of sub stantially the following composition: copper,' 0.37-0.50%; vanadium, 0.424178%; molybdenum, 5.72-7.44%; copper, 1.51-2.66%; boron, 0.39%; and iron, 88.29-91.57%.'

6. A high-speed steel free of chromium in excess of 1.50%-of the iron content, and of substantially the following composition: carbon,

0.50%; vanadium, 0.78%; molybdenum, 7.44%; 80

copper, 2.66%; boron, 0.33%; and iron, 88.29%.

ELMER'B. WELCH.