US2026574A - Free cutting alloys - Google Patents

Free cutting alloys Download PDF

Info

Publication number
US2026574A
US2026574A US19625A US1962535A US2026574A US 2026574 A US2026574 A US 2026574A US 19625 A US19625 A US 19625A US 1962535 A US1962535 A US 1962535A US 2026574 A US2026574 A US 2026574A
Authority
US
United States
Prior art keywords
per cent
aluminum
alloys
bismuth
alloy
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US19625A
Inventor
Louis W Kempf
Walter A Dean
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Howmet Aerospace Inc
Original Assignee
Aluminum Company of America
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US689883A external-priority patent/US2026545A/en
Application filed by Aluminum Company of America filed Critical Aluminum Company of America
Priority to US19625A priority Critical patent/US2026574A/en
Application granted granted Critical
Publication of US2026574A publication Critical patent/US2026574A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/003Alloys based on aluminium containing at least 2.6% of one or more of the elements: tin, lead, antimony, bismuth, cadmium, and titanium

Definitions

  • This invention relates to aluminum base alloys and it is especially concerned with those alloys containing a substantial amount of zinc.
  • Aluminum base alloys containing zincasamajor alloying component have been widely used in both cast and wrought form because of their good casting and working qualities combined with satisfactory physical properties such as strength and ductility.
  • Certain alloys having an aluminum-zinc base have been developed which have unusually high tensile and shear strengths on the order of 65,000 and 40,000 pounds per square inch, respectively.
  • Thermal treatments are generally employed to improve the strength of the alloys and attain the high values indicated.
  • An alloy in which such properties are attainable under suitable treatment is one containing from about 7 to 15 per cent of zinc, 0.5 to 2.5 per cent of copper, 0.2 to 2.5 per cent of magnesium, and 0.1 to 1.5 per cent of manganese.
  • This alloy is especially well adapted to the production of forged articles such as typewriter segments, gasoline pump handles, and the like, because of the excellent hot working quality of the metal.
  • it is necessary to employ some machining operation such as boring, drilling, planing, shaping and the like to complete the article for use. While these operations have been performed on the aforesaid alloy in the past, the machining quality has not been such as to facilitate the finishing operations because of the precautions necessary to obtain an acceptably smooth surface without the dragging of metal on the cutting tool edge.
  • the deficiency in machinability is also evidenced by the long curled chips that are produced which may foul the cutting tool or operating parts of the ma chine. The tendency of the metal to drag under the tool edge results in an-uneven cut and a dull irregular machined surface which is obviously undesirable.
  • the machining quality of the aluminum base alloys containing from about 7 to 15 per cent of zinc, 0.5 to 2.5 per cent of copper, 0.2 to 2.5 per cent of magnesium, and 0.1 to 1.5 per cent of manganese may be markedly improved by the addition thereto of at least one of the elements lead, thallium, and bismuth. These elements are advantageously added in amounts of from about 0.1 to 6 per cent either separately or in combination. Alloys so formed possess excellent machining characteristics which may be described as being "free machining or free cutting. Alloys of this nature maybe readily cut on automatic machines at higher speeds than other allows while still retaining dimensional accuracy and a satisfactory machined surface.
  • the elements lead, thallium, and bismuth are designated "free machining constituents or elements and are regarded as being substantially equivalent by reason of the similarity in eiTect upon the machining quality of the alloys herein disclosed.
  • While lead, bismuth, and thallium may be used in amounts of from about 0.1 to 6 per cent as set forth hereinabove, we prefer to use between about 1 and 4 per cent of these free machining constituents in alloys of the class de scribed.
  • the advantages gained from the use of the above named elements are especially evident in alloys containing from about 8 to 12 per cent of zinc, from about 0.5 to 1.5 per cent of copper, from about 0.5 to 1.5 per cent of magnesium, and 0.5 to 1 per cent of man ganese, the balance being substantially all aluminum.
  • the case of an alloy may be cited where the alloy was composed of about 9.5 per cent of zinc, 0.8 per cent copper, 0.5 per cent magnesium, and 0.8 per cent manganese, the balance being aluminum.
  • the alloy was composed of about 9.5 per cent of zinc, 0.8 per cent copper, 0.5 per cent magnesium, and 0.8 per cent manganese, the balance being aluminum.
  • lead By the addition of about 4 per cent of lead a smooth bright regularly cut machined surface was obtained on the article when machined.
  • the chips were short and easily broken so that danger of fouling the cutting tool was eliminated as compared to the long spirals obtained from the alloy containing no free machining constituent.
  • the tensile properties of the alloy were not materially affected by the presence of lead.
  • the elements bismuth and thallium produce an improvement in machining quality similar to that obtained through the use of lead.
  • the elements lead, bismuth, and thallium may be advantageously "is preferred to keep the total below about 6 per cent.
  • a surprising fact discovered concerning the behavior of alloys containing two or more of the free machining constituents is that a superior degree of machinability is often obtained in such cases as compared to the same base alloy with an equivalent amount of only one element present.
  • the tensile properties of the alloys are not materially altered by the addition of the free machining constituents in amounts up to about 4 per cent. Beyond this amount there is a decline in strength but this is accompanied by a somewhat better machinability of the alloy because of the increased amount of free machining constituent.
  • the amount of lead, thallium and/or bismuth to be chosen for a given alloy is dependent upon the strength and degree of machinability required.
  • the free machining constituents are most conveniently added in solid elemental form to the molten aluminum alloy since they melt at a temperature considerably below that ordinarily encountered in aluminum alloy melting practice. If more than about 1.5 per cent of these constituents is to be added to the alloy, the temperature of the molten bath should be raised above that commonly employed, the desired metals added, and the molten mass vigorously stirred to insure a thorough mixing of the metals.
  • the method here referred to of adding heavy low melting point metals to aluminum is more fully described, in co-pending application, Serial No. 689,885, now issued as U. S. Patent No. 1,959,029.
  • aluminum used herein and in the appended claims embraces the usual impurities found in aluminum ingot of commercial grade, or picked up in the course ot the usual handling operations incident to ordinary melting practice.
  • alloys herein disclosed may be subjected to the usual thermal treatments familiar to those skilled in the art for the purpose of improving 5 or altering their physical characteristics.
  • An aluminum base alloy containing from about I to 15 per cent of zinc, from about 0.5 to 2.5 per cent of copper, from about 0.2 to 2.5 per 10 cent of magnesium, from about 0.1 to 1.5 per cent of manganese and from about 0.1 to 6 per cent of bismuth, the balance being aluminum.
  • An aluminum base alloy containing from about '7 to 15 per cent of zinc, from about 0.5 to 15 2.5 per cent of copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese, and from about 1 to 4 per cent of bismuth, the balance being aluminum.
  • An aluminum base alloy containing from 20 about '1 to 15 per cent of zinc, from about 0.5 to 2.5 per cent 0! copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese, and about 4 per cent of bismuth,
  • An aluminum base alloy containing from about 7 to 15 per cent oi zinc, from about 0.5 to 2.5 per cent or copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese and about 2 per cent 0! bis- 30 muth, the balance being aluminum.
  • An aluminum base alloy containing about 9.5 per cent of zinc, 0.8 per cent of copper, 0.5 per cent of magnesium, 0.8 per cent of manganese and 4 per cent 01' bismuth. the balance 35 being aluminum.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Description

Patented Jan. 7, 1936 UNITED STATES FREE CUTTING ALLOYS Louis W. Kempf and Walter A. Dean,
Cleveland,
Ohio, assignors to Aluminum Company of America, Pennsylvania No Drawing. Original 1933, Serial No.
plicationMay 3, 1935,
7 Claims.
This invention. relates to aluminum base alloys and it is especially concerned with those alloys containing a substantial amount of zinc.
This application is a division of our co-pending application, Serial No. 689,883, filed September 18, 1933. Alloys disclosed but not claimed herein are claimed in our abovementioned application, Serial No. 689,883 and in our co-pending application, Serial No. 19,624, filed May 3, 1935.
Aluminum base alloys containing zincasamajor alloying component have been widely used in both cast and wrought form because of their good casting and working qualities combined with satisfactory physical properties such as strength and ductility. Certain alloys having an aluminum-zinc base have been developed which have unusually high tensile and shear strengths on the order of 65,000 and 40,000 pounds per square inch, respectively. Thermal treatments are generally employed to improve the strength of the alloys and attain the high values indicated. An alloy in which such properties are attainable under suitable treatment is one containing from about 7 to 15 per cent of zinc, 0.5 to 2.5 per cent of copper, 0.2 to 2.5 per cent of magnesium, and 0.1 to 1.5 per cent of manganese. This alloy is especially well adapted to the production of forged articles such as typewriter segments, gasoline pump handles, and the like, because of the excellent hot working quality of the metal. In finishing such articles as those named and many others, it is necessary to employ some machining operation such as boring, drilling, planing, shaping and the like to complete the article for use. While these operations have been performed on the aforesaid alloy in the past, the machining quality has not been such as to facilitate the finishing operations because of the precautions necessary to obtain an acceptably smooth surface without the dragging of metal on the cutting tool edge. The deficiency in machinability is also evidenced by the long curled chips that are produced which may foul the cutting tool or operating parts of the ma chine. The tendency of the metal to drag under the tool edge results in an-uneven cut and a dull irregular machined surface which is obviously undesirable.
It is accordingly an object of our invention to overcome these obstacles to easy and economical machining of alloys of the type disclosed above. Another object is to accomplish the foregoing purpose without detrimental eflect upon the casting. working, and physical properties or susceptibility to thermal treatments.
Our invention is predicated upon the discovery Pittsburgh,
application 689,883. Divided and this ap- Serial No. 19,625
Pa., a corporation of September 18,
that the machining quality of the aluminum base alloys containing from about 7 to 15 per cent of zinc, 0.5 to 2.5 per cent of copper, 0.2 to 2.5 per cent of magnesium, and 0.1 to 1.5 per cent of manganese, may be markedly improved by the addition thereto of at least one of the elements lead, thallium, and bismuth. These elements are advantageously added in amounts of from about 0.1 to 6 per cent either separately or in combination. Alloys so formed possess excellent machining characteristics which may be described as being "free machining or free cutting. Alloys of this nature maybe readily cut on automatic machines at higher speeds than other allows while still retaining dimensional accuracy and a satisfactory machined surface. For the purpose of our invention the elements lead, thallium, and bismuth are designated "free machining constituents or elements and are regarded as being substantially equivalent by reason of the similarity in eiTect upon the machining quality of the alloys herein disclosed.
While lead, bismuth, and thallium may be used in amounts of from about 0.1 to 6 per cent as set forth hereinabove, we prefer to use between about 1 and 4 per cent of these free machining constituents in alloys of the class de scribed. The advantages gained from the use of the above named elements are especially evident in alloys containing from about 8 to 12 per cent of zinc, from about 0.5 to 1.5 per cent of copper, from about 0.5 to 1.5 per cent of magnesium, and 0.5 to 1 per cent of man ganese, the balance being substantially all aluminum. As an example of the improvement in machinability gained through the use of free machining constituents the case of an alloy may be cited where the alloy was composed of about 9.5 per cent of zinc, 0.8 per cent copper, 0.5 per cent magnesium, and 0.8 per cent manganese, the balance being aluminum. By the addition of about 4 per cent of lead a smooth bright regularly cut machined surface was obtained on the article when machined. The chips were short and easily broken so that danger of fouling the cutting tool was eliminated as compared to the long spirals obtained from the alloy containing no free machining constituent. The tensile properties of the alloy were not materially affected by the presence of lead. The elements bismuth and thallium produce an improvement in machining quality similar to that obtained through the use of lead.
It has also been found that the elements lead, bismuth, and thallium may be advantageously "is preferred to keep the total below about 6 per cent. A surprising fact discovered concerning the behavior of alloys containing two or more of the free machining constituents is that a superior degree of machinability is often obtained in such cases as compared to the same base alloy with an equivalent amount of only one element present. An alloy, for example, containing about 9.5 per cent zinc, 0.8 per cent copper, 0.5 per cent magnesium, 0.8 per cent manganese, 2 per cent of lead, and 2 per cent of bismuth, balance substantially all aluminum, had better machining characteristics than the same alloy containing 4 per cent of bismuth instead of a combination of lead and bismuth.
The tensile properties of the alloys are not materially altered by the addition of the free machining constituents in amounts up to about 4 per cent. Beyond this amount there is a decline in strength but this is accompanied by a somewhat better machinability of the alloy because of the increased amount of free machining constituent. The amount of lead, thallium and/or bismuth to be chosen for a given alloy is dependent upon the strength and degree of machinability required.
The free machining constituents are most conveniently added in solid elemental form to the molten aluminum alloy since they melt at a temperature considerably below that ordinarily encountered in aluminum alloy melting practice. If more than about 1.5 per cent of these constituents is to be added to the alloy, the temperature of the molten bath should be raised above that commonly employed, the desired metals added, and the molten mass vigorously stirred to insure a thorough mixing of the metals. The method here referred to of adding heavy low melting point metals to aluminum is more fully described, in co-pending application, Serial No. 689,885, now issued as U. S. Patent No. 1,959,029.
The term aluminum used herein and in the appended claims embraces the usual impurities found in aluminum ingot of commercial grade, or picked up in the course ot the usual handling operations incident to ordinary melting practice.
The alloys herein disclosed may be subjected to the usual thermal treatments familiar to those skilled in the art for the purpose of improving 5 or altering their physical characteristics.
We claim:
1. An aluminum base alloy containing from about I to 15 per cent of zinc, from about 0.5 to 2.5 per cent of copper, from about 0.2 to 2.5 per 10 cent of magnesium, from about 0.1 to 1.5 per cent of manganese and from about 0.1 to 6 per cent of bismuth, the balance being aluminum.
2. An aluminum base alloy containing from about '7 to 15 per cent of zinc, from about 0.5 to 15 2.5 per cent of copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese, and from about 1 to 4 per cent of bismuth, the balance being aluminum.
3. An aluminum base alloy containing from 20 about '1 to 15 per cent of zinc, from about 0.5 to 2.5 per cent 0! copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese, and about 4 per cent of bismuth,
' the balance being aluminum. 25
4. An aluminum base alloy containing from about 7 to 15 per cent oi zinc, from about 0.5 to 2.5 per cent or copper, from about 0.2 to 2.5 per cent of magnesium, from about 0.1 to 1.5 per cent of manganese and about 2 per cent 0! bis- 30 muth, the balance being aluminum.
5. An aluminum base alloy containing about 9.5 per cent of zinc, 0.8 per cent of copper, 0.5 per cent of magnesium, 0.8 per cent of manganese and 4 per cent 01' bismuth. the balance 35 being aluminum.
6. An aluminum base alloy 'containing from about 8 to 12 per cent of zinc, from about 0.5 to 1.5 per cent-of copper, 0.5 to 1.5 per cent of magnesium, from about 0.5 to 1 per cent of man- 49 ganese, and from about 0.1 to 6 per cent 0! bismuth, the balance being aluminum.
7. An aluminum base alloy containing from about 8 to 12 per cent of zinc, from about 0.5 to
1.5 per cent of copper, from about 0.5 to 1.5 per 5 cent of magnesium, from about 0.5 to 1 per cent of manganese and from about 1 to 4 per cent of bismuth, the balance being aluminum.
' LOUIS W. KEMPF.
WALTER A. DEAN. 50
US19625A 1933-09-18 1935-05-03 Free cutting alloys Expired - Lifetime US2026574A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US19625A US2026574A (en) 1933-09-18 1935-05-03 Free cutting alloys

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US689883A US2026545A (en) 1933-09-18 1933-09-18 Free cutting alloys
US19625A US2026574A (en) 1933-09-18 1935-05-03 Free cutting alloys

Publications (1)

Publication Number Publication Date
US2026574A true US2026574A (en) 1936-01-07

Family

ID=26692414

Family Applications (1)

Application Number Title Priority Date Filing Date
US19625A Expired - Lifetime US2026574A (en) 1933-09-18 1935-05-03 Free cutting alloys

Country Status (1)

Country Link
US (1) US2026574A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742688A (en) * 1952-06-18 1956-04-24 Aluminum Co Of America Duplex aluminous products and articles

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742688A (en) * 1952-06-18 1956-04-24 Aluminum Co Of America Duplex aluminous products and articles

Similar Documents

Publication Publication Date Title
US2026574A (en) Free cutting alloys
US2026546A (en) Free cutting alloys
US2026575A (en) Free cutting alloys
US2026573A (en) Free cutting alloys
US2026549A (en) Free cutting alloys
US2026545A (en) Free cutting alloys
US2026541A (en) Free cutting alloys
US2076575A (en) Free cutting alloys
US2076571A (en) Free cutting alloys
US2026551A (en) Free cutting alloys
US2026542A (en) Free cutting alloys
US2026576A (en) Free cutting alloys
US2076569A (en) Free cutting alloys
US1986825A (en) Free cutting alloy
US2026547A (en) Free cutting alloys
US2026540A (en) Free cutting alloys
US2026548A (en) Free cutting alloys
US2026555A (en) Free cutting alloys
US2076567A (en) Free cutting alloys
US2026543A (en) Free cutting alloys
US2026566A (en) Free cutting alloys
US2026562A (en) Free cutting alloys
US2026565A (en) Free cutting alloys
US2026561A (en) Free cutting alloys
US2076574A (en) Free cutting alloys