US3788843A - Steel having improved free-cutting properties - Google Patents

Steel having improved free-cutting properties Download PDF

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Publication number
US3788843A
US3788843A US00158217A US3788843DA US3788843A US 3788843 A US3788843 A US 3788843A US 00158217 A US00158217 A US 00158217A US 3788843D A US3788843D A US 3788843DA US 3788843 A US3788843 A US 3788843A
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steel
cutting
free
steels
abrasion
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US00158217A
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T Mimino
K Nishikawa
S Nara
Y Miyashita
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JFE Engineering Corp
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Nippon Kokan Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

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  • This invention relates to steel compositions and more particularly to steels having improved free-cuttmg properties.
  • steel displaying excellent abrasion resistance may be recognized as the best suited for cutting jobs, such as when used in a tool.
  • Steel which may be, for example, a sulphur (S) freecutting steel containing about 0.3% S, a lead (Pb) freecutting steel containing 0.15% to 0.3% Pb, or a sulphurlead free-cutting steel containing both S and Pb have been employed for the above purpose. It is however, wellknown that the utility of these steels is limited by reason of certain common defects existing in these steels, such as that such steels are confined to cutting jobs performed at low speeds.
  • S sulphur
  • Pb lead
  • the calcium (Ca) free-cutting steel was thus developed.
  • This steel contains more than 0.002% Ca and an adjusted amount of S01. Al.
  • the percents recited herein refers to percentage by weight.
  • This steels ability to be machined is improved over that discussed above, to be suitable for cutting work at high speeds.
  • the Ca free-cutting steel had large dispersions of abrasion amount when employed in a tool and hence the depth of abrasion was close to that of ordinary steel. There was only slight possibility that such dispersion could be reduced.
  • the relative amounts of Ca and S01. A1. are difiicult to adjust to the most suitable level, with concurrent stability.
  • a calcium-sulphur free-cutting steel comprising the addition of S to steel, in order to remove the foregoing defect.
  • the abrasion amount of a tool employing Ca-S free-cutting steel is reduced to smaller dispersions and less depth.
  • this steel is still deficient in certain mechanical properties.
  • an object of this invention is to provide a machine structure steel stably displaying excellent freecutting properties with the least abrasion amount when employed in a tool at high speeds.
  • Another object of this invention is to provide a steel which reduces the working cost when used in cemented carbide tools.
  • a further object of this invention is to provide a steel possessing better mechanical properties and better freecutting properties than those of known steels.
  • a steel comprising the addition of 0.002% to 0.02% Ca, 0.005% to 0.04% Sol. Al. and 0.005% to 0.1% niobium (Nb) and/or vanadium (V) to the known compositions of ordinary machine structure steels.
  • FIG. 1 is a graph depicting the relation between Ca percent and S01. Al. percent in a known Ca free-cutting steel and the resulting influence on abrasion of a tool employing such steel;
  • FIG. 2 is a graph depicting how the abrasion amount of a tool using a known Ca free-cutting steel is changed with passage of cutting time, in comparison with that of basic steel;
  • FIG. 3 is a diagram depicting the relation between Ca percent and S01. Al. percent as shown in FIG. 1 plotting with actual samples;
  • FIG. 4 is a graph depicting how the abrasion amount of a tool using a known Ca-S free-cutting steel is changed with passage of cutting time, in comparison with basic steel;
  • FIG. 5 is a diagram depicting the relation between Ca percent and S01. Al. percent in a Ca-S steel as plotted with actual samples;
  • FIG. 6 is a graph depicting the abrasion amount of a tool using the steel of this invention as changed with passage of cutting time, and plotted using a comparison with each of several steels.
  • FIG. 7 depicts a graph showing how the abrasion amount of a tool using the steel of this invention is changed with the passage of cutting time, in comparison with other steels.
  • FIG. 1 there is depicted a graph showing the relation between Sol. Al percent and Ca percent in a Ca free-cutting steel. This steel was produced by adding Ca to the basic steel discussed above and to be discussed in greater detail hereinbelow. There is depicted a zone showing good abrasion resistance. Experiments have shown that Ca free-cutting steel has large dispersions of amount of dispersive abrasion.
  • FIG. 3 depicts the relation as plotted with actual data from actual samples.
  • FIGS. 2 and 3 depict the amount of abrasion depth as measured against cutting time. It can be readily understood that the increase of depth of abrasion with time is not desirable.
  • FIG. 5 there is depicted a plot of data obtained with actual examples of Ca-S free-cutting steel, measuring Sol. Al percent against Ca percent. The cutting time was 10 minutes.
  • FIG. 4 there is depicted the depth of abrasion as measured against time for a Ca-S freecutting steel. The depth does not increase in any substantial manner with passage of cutting time. This is probably 3 due to the addition of more than 0.04% S to the Ca steel discussed above with reference to FIG. 1.
  • All of the machine structure steel as shown in American Standards, i.e. A151 and the like, may be utilized as a basic starting point to which the other components of this inventive steel are added.
  • the basic steel may be selected from common carbon steels, heat resisting steels, chromium molybdenum steels, nickel chromium molyb denum steels or the like.
  • Charge No. 1 steel is based on known steel AISI-l045 and is regarded as a basic steel to which the other elements may be added in accordance with this invention.
  • Charge No. 2 steel is a Ca free-cutting steel produced by adding Ca to the basic steel such as of Charge No. 1.
  • Charge No. 3 steel is another Ca free-cutting steel.
  • Charge No. 4 steel is a Ca-S freecutting steel produced by adding S to the Ca free-cutting steel such as of Charge No. 2.
  • Charge No. 5 steel is a Ca-Nb free-cutting steel produced by adding Nb to the Ca free-cutting steel such as of Charge No. 2, but, the S01. Al. content is more than that of the present inventive Sol. AL, and Nb and/ or V is added to each of the above steel.
  • inventive steels a new steel, which is the present inventive steel was produced.
  • the inventive steel displays outstanding free-cutting properties and excellent mechanical properties as a machine structure steel. It is readily attained to perfection with ease and stability.
  • C silicon (Si) and manganese (Mn) which are common elements in the above steels should be within certain ranges.
  • C should preferably range from 0.08% to 0.6%; Si should preferably range from 0.15% to 0.60%; and Mn should preferably range from 0.30% to 2.00%. More than 0.6% C reduces the workability of steel and less than 0.08% C will substantially reduce the advantageous etfects of C as required in a machine structure steel, such as hardness. Si and Mn are useful for deoxidation, and increasing yield strength and tensile strength of steel with low cost. However, when the Si content is more than 0.6% or Mn is more than 2.00%, the toughness of the steel is adversely affected. Conversely,
  • each of the elements, Ca, Sol. Al., and Nb and/or V should be further added together with the above-mentioned basic elements or other elements specified in the variously used standards.
  • the added ranges of Ca., Sol. Al., Nb. and V. are as follows: Ca is from 0.002% to 0.02%; Sol. Al. is from 0.005% to 0.04%; and Nb. and/or V. is from 0.005% to 0.1%.
  • Ca is from 0.002% to 0.02%
  • Sol. Al. is from 0.005% to 0.04%
  • Nb. and/or V. is from 0.005% to 0.1%.
  • the Ca content is more than 0.02%, workability of the resulting steel is reduced substantially and its cost increased, Conversely, less than 0.002% of Ca will Charge No. 6 steel is a Ca-V free-cutting steel produced by adding V to a Ca free-cutting steel such as of Charge No.
  • Charge No. 7 steel is a Ca-Nb free-cutting steel produced in accordance with this invention.
  • Charge No. 8 steel is a Ca-V free-cutting steel produced in accordance with this invention.
  • cutting tool A cemented carbide tool bit. cutting speed: m./min.
  • FIG. 6 there is depicted in graphic format, the abrasion properties of a tool using the steel samples of Charges Nos. 1-8 discussed above and shown in Table II. From FIG. 6, it can be readily understood that the abrasion amount of a tool using the basic steel of Charge No. l is large and for Ca free-cutting steel of Charges Nos. 2 and 3, which were developed to improve the free-cutting properties of basic steel, abrasion amount is unstable. Charge No. 3 steel shows a considerable amount of abrasion as cutting time passes. The amount of abrasion of Charge No. 2 steel is very small and is comparatively stable.
  • Ca-S free-cutting steel of Charge No. 4 was developed to stabilize the free-cutting properties of Ca steel and is 6 restricted.
  • the new steels of this invention are not so restricted.
  • the abrasion amount of a tool using the steel produced in accordance with this invention is superior to that of the Ca-S free-cutting steels and is also outstanding in stability, that is to say that the abrasion depth does not change significantly with passage of time.
  • the mechanical properties of each of the steels produced using the principles of this invention are excellent and substantially better than those of the other above steels.
  • the S01. Al. content is within a certain range; as well as the amount of each of the other elements Ca and Nb and/or V are within the above discussed ranges.
  • the steel charges having Sol. Al. contents outside of the ranges of this invention are shown as comparative examples. These comparative samples are Charges Nos. 5 and 6 Steel in FIG. 6. Referring to FIG. 6, it can be readily understood that the abrasion resistance of a tool using steels having Sol. Al. contents more than 0.04% become substantially worse.
  • FIG. 7 there is depicted a graph showing the change of amount of abrasion of a tool using the new steel produced according to the invention, with the passage of cutting time, as compared with that of other typical steels.
  • the graph data are the results of plotting data obtained through many experiments and samples. From the FIG. 7, it can be readily understood that the free-cutting properties of this invention has little dispersion and outstanding stability. The depth of abrasion does not increase in any significant amount with passage of cutting time.
  • Steel composition consisting essentially of 0.002% to 0.02% Ca; 0.005% to 0.04% sol. Al.; 0.005% to 0.1% Nb and/or V; 0.08% to 0.60% C; 0.15% to 0.60% Si; 0.30% to 2.00% Mn and balance Fe and unavoidable traces.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)
  • Heat Treatment Of Steel (AREA)
US00158217A 1970-06-30 1971-06-30 Steel having improved free-cutting properties Expired - Lifetime US3788843A (en)

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US (1) US3788843A (fr)
CA (1) CA947122A (fr)
CH (1) CH526638A (fr)
DE (1) DE2132561A1 (fr)
FR (1) FR2101528A5 (fr)
GB (1) GB1347345A (fr)
SE (1) SE392292B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2421604A1 (de) * 1973-05-04 1974-11-14 Nippon Steel Corp Rostfreier stahl
US4172716A (en) * 1973-05-04 1979-10-30 Nippon Steel Corporation Stainless steel having excellent pitting corrosion resistance and hot workabilities

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2421604A1 (de) * 1973-05-04 1974-11-14 Nippon Steel Corp Rostfreier stahl
US4172716A (en) * 1973-05-04 1979-10-30 Nippon Steel Corporation Stainless steel having excellent pitting corrosion resistance and hot workabilities

Also Published As

Publication number Publication date
CH526638A (fr) 1972-08-15
GB1347345A (en) 1974-02-20
DE2132561A1 (de) 1972-02-17
SE392292B (sv) 1977-03-21
CA947122A (en) 1974-05-14
FR2101528A5 (fr) 1972-03-31

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