US1775615A - Alloy steel - Google Patents

Description

Patented Sept. 9, 1930 '.THN "A: subcon- -oFHTTsBURGm f'ENNsYLVlu\IfA;-s-AssIGNoRnTo iHEvrrEiNsTALL comi# iLofY articles Capableof'withstandinggrpiddge yclestructoIl andfyyhicbfre readily' madepud 15,falorjated.I 1 f l Itsfn-mon..

IeLjs-Qandmalrt e edges having long usef 'llifejt The (alloy steels yvrf'nvid d lsteels7 simhfasf-manganeselan s111091;1 30 l f EI-mits? broaderaspectsv t, te .mjregalinonl conals@l of rhol" 571th th more desirablenpbyscal.. propertle Within v`these,rangeY of` V 201-DPQS v II P31- wf tulal'ly-5les`irab1eresults are obtained by vajryihggfh; Conteuts of carbon, molybdenum and. nikelwithl respect .to chromium1 in a Vmanner hereinafter set forthf--M-m 'nsl these alloys may bequenched at tepituies dover a considerable range off-Stemp erties. On the coutfgy,

hout adversely affecting so Steel A Steel B Per cmi Per cent Carbon 0. 70 1. 75 Chromium 10. 16.0 fMnnnnnpsa 0.25 0. 25 Molybdenum-. 0.40 l. 50 Nickel 0. 80 2. 0 Silicon 0. 35 0. 35 Vanadium 0, 3D 1. 00

Samples of these three steels were heat treated simultaneously, by quenching from about 17 50-1800 F., followed by drawing at various temperatures, after which physical tests were made. The results obtained are shown in the following table:

Tensile Elon iza- Hardness lgretg tion per Brnell n q' cent'in 2' vNo.

Swedish steel:

Tempered at 560 F 254,000 4. 0 480 Tempered at 750 F-. 200, 000 7. 0 400 Steel A:

Tempered at 560 F 290, 500 2.0 600 Tempered at 750 F 280,000 2. 5 p 600 Steel B: i

Tempered at 560 F 325,000 1. 8 600 Tempered at 750 F 305, 000 2. 0 600 These data show that much greater tensile strengthsare obtained, with concomitant greater hardness from my new steels, and that drawing over this range does not apparently affect the hardness, whereas the hardness of the Swedish steel decreases substantially. Further tests showing these properties follow:

Tensile Elongastrength, tion, per girxlllsls lbs. per cent in No sq. in.

Steel A:

Tempered at 930 F 271, 000 3. 5 589 Tempered at 1100 F 225, 000 6. 8 555 Steel B: L

Tempered at 930 F 300,000 2. 7 600 Tempered at 1100 F 270, 000 4.] 587 My present belief is that the remarkable properties of these alloys result from the use of a balanced composition in which the various constituents coact to produce a structure in which coalescence of excess carbides into a network structure `is prevented. It appears the composition of the steels is such that proper heat treatment of these alloys produces a structure comprising' minute carbide particles embedded in a matrix composed principally of a solid solution or solid solutions of nickel, molybdenum and vanadium in iron, from which the carbide is not readily rejected, this being a martensitic structure.' The matrix provides the substantial toughness, fibre strength, and ductility which is characteristic of the alloys provided by the invention, while hardness results from the dispersion in the matrix of the exceedingly hard particles of carbide, hardness retention beingr favored by the minimized tendency toward carbideI rejection.

Whether or not the foregoing belief as to the structural composition of the new steels is correct, it is a fact that the new steels develop a refined structure possessing a combination of very high ductility, fibre or cohesive strength, and hardness which adapts them especially for the production of keen edged articles in which these properties manifest themselves by resistance to edge destruction. Although flint hardness is not always a prerequisite in the production of satisfactory cutting edges, it is possible to obtain with these alloys a Brinell hardness number of over 600, a hardness on the Rockwell C scale of over 65, or sceleroscope of more than 85. Furthermore, after heat treatment, and particularly upon being highly polished, articles made from them possess substantial surface stability. evidenced by resistance to corrosion as by etching reagents, tarnishing and atmospheric oxidation.

These desirable properties are apparently due to a balance between the constituents, and in varying the composition of the alloys within the ranges given, the most suitable results are obtained by controlling the contents of carbon, molybdenum and nickel in accordance with variations in the chromium content. More specifically my tests have shown that to obtain the best results, within the preferred ranges at least, as the chromium is increased from 10 to 16 per cent the molybdenum and nickel contents vary according to practically straight lineratios between 0.4 and 1.5 per cent, and between 0.8 and 2.0 per cent respectively. Also, as chromium is increased within the same limits, carbon is preferably increased from 0.7 to 1.75 per cent, the increments being greater for the lower ranges of chromium, and becoming smaller toward the upper limits. Stated in other Words, within the ranges given molybdenum and nickel .vary in substantially direct proportion to the chromium content, while the carbon content variably increases at a diminishing rate as the chromium content increases.

The combination of physical properties capable of being developed in these alloys ,from each blade.

confers the further advantagethat it makes possible the production of thin sections having intricate designs, such yas those of the recent types of safety razor blades, in which the article," because of its high ductility, resists breakage either -in manufacture or in use. For example, a wafer type razor blade having a thickness of 0.006 inch held at the ends can be bent repeatedly to an angle of forty-five degrees without breaking or taking a permanent set.

' The properties of these alloys render them particularly suitable for the production of razorblades, not only because their cutting edges possess unusual resistance to abrasion and edge destruction, but also for the reason that rusting and electrolytic action, for example between the blade and its holder, is re-. duced to such a point that the necessity of thoroughly drying parts before storage is substantially eliminated. Such blades therefore possess materially longer life than those heretofore commercially available.

In the production of razor blades it is preferred to use alloys of about the following composition:

Per cent Carbon 0.70 to 0.7 5 Chromium 10.0 to 12.00 Manganese 0.15 to 0.30 Molybdenum 0.40 to 0.50 Nickel 0.80 to 1.00 Silicon 0.20 to 0.45 Vanadium 0.35 to 0.45 Iron Balance .hundred sets of razor blades each comprisin a blade made from an allo of the preferre composition just given lade A), a blade made from Athe best razor blade steel heretofore available (Blade B), anda standard commercial blade (Blade C) were distributed for the purpose of obtaining an unbiased and disinterested test, the results being reported in number of satisfactory shaves had A tabulation of the results follows:

Number of shaves Blade C Blade B Blade A Average 3 11 24 Highest individual- 7 24 50 These results show the marked superiorityv of blades made from my alloys.' They show plate, where knives made from these alloys possessed a useful life of weeks, while t speciically described what I now consider vto represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim: A

1. An lalloy steel for the production of abrasion-resistant edged articles and having a martensitic structure, the alloy consisting of from about 0.5 to 2.0 per cent of carbon, from about 5.0 to 20.0 per cent of chromium, from about 0.1 to 1.75 per cent of manganese, fromabout 0.1 to 2.0 per cent of molybdenum, from about 0.25 to 3.5 per cent of nickel, from about 0.1 to 2.0 per cent of silicon, and from about 0.1 to 1.5 per cent of vanadium, the remainder being iron except for elements present as impurities and in amounts insuffi- `cient to materially alter the physical and abrasion-resistant properties of said alloy, the elements of the alloy being balanced by varying between the stated limits the molybdenum and nickel contents in substantially direct proportion to changes in chromium coutent, and by variably increasing the carbon content at a diminishing rate as the chromium is increased.

2. An alloy steel for the production of abrasion-resistant edged articles and having a martensitic structure, the alloy consisting of from about 0.6 to 1.75 per cent of carbon,

from about 10.0 to 16.0 per cent of chromium, from about 0.1 to 0.75 per cent of manganese, from about 0.4 to 1.5 per cent of molybdenum, from about 0.8 to 2.0 per cent of nickel, from about 0.1 to 0.75 per cent of silicon, and from about 0.3 to 1.0 per cent of vanadium, the re; mainder being iron except for elements present as impurities and in amounts insufcient Inn to materially alter the physical and abrasionresistant properties of said alloy, the ele-- ments of the alloy being balanced by varying between the stated limits the molybdenum and nickel contents in substantially direct proportion to changes in chromium content, and by variably increasing the carbon content at adiminishing rate as the chromium is increased. v

In testimony whereof, IA sign m name.

JOHN A. s ocoP.