Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

• a wet chemical pickling treatment is required to remove the copper-zinc oxide which has formed on the surface of the brass during the annealing in air.
• Sulphuric acid is usually employed for pickling, although its use involves considerable difficulties as regards the purification of water.
• a pickling plant involves a high capital requirement particularly when the stock to be pickled consists of bundles of long brass tubes and an attempt is made to accomplish a uniform pickling of the inside surface of the tubes throughout the length in a vacuum in a so-called autoclave. Detrimental substances cannot be avoided even if the waste water is optimally neutralized. For this reason, the process previously employed to pickle semifinished brass stock after the processannealing is not satisfactory.
• the semifinished stock which may have been degreased, if desired, is annealed at a temperature of 350600 C., preferably 430530 C., in a hydrogen-nitrogen atmosphere which contains 3-99.5% hydrogen, less than 0.08% carbon dioxide, less than 0.01% water vapour, less than 0.001% oxygen, up to 5% carbon monoxide, balance nitrogen.
• this hydrogen-nitrogen inert gas contains only very small amounts of oxygen, water vapour and carbon dioxide and due to this high purity has a very high reduction potential which in fact results in a bright annealing of the brass. This has not been possible before and is due to the fact that the zinc vapour pressure at the selected recrystallizing temperature is such that it does not adversely affect the bright recrystallization.
• the subsequent annealing will not result in a discolouration of the surface, which would otherwise be caused by the cracking of adhering lubricants or the like. Because the annealing is thus a real bright annealing, there is no longer a need for any subsequent surface treatment by pickling or the like, which would involve the disadvantages and difficulties which have been described.
• the semifinished stock are degreased by being heated to 250400 C. under a vacuum so that the lubricant or the like adhering to the surface evaporates.
• the degreasing may be accomplished in the same furnace and there is no need to change the charge or to cool the stock before the actual annealing.
• Semifinished brass stock (brass wire, cold-rolled brass strip, cold-drawn brass tubes) of Ms 63 grade brass, free of lead, were heated to 350 C. within 3 hours under a vacuum in a vacuum pot annealing furnace provided with means for circulating inert gas. During that time, the lubricant which adhered to the surface as a result of the cold working of the stock evaporated without leaving a residue. The furnace was then scavenged with inert gas; its temperature was raised to 470 C. and held for 3 hours on that level. The inert gas was vigorously circulated during that time.
• the inert gas had the following composition: 15% H less than 0.001% CO less than 0.0005% H O, less than 0.0001% 0 less than 2% CO, balance N
• the charge was then cooled to room temperature during 12 hours, while the inert gas was kept in circulation.
• the resulting semifinished stock was prefectly bright and had been completely recrystallized.
• a recrystallizing annealing process for treating semifinished brass stock which comprises annealing the semifinished stock at a temperature of 350600 C. in a hydrogen-nitrogen atmosphere which consists of 399.5% hydrogen, less than 0.08% carbon dioxide, less than 0.01% water vapour, less than 0.001% oxygen, up to 5% carbon monoxide, balance nitrogen.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Heat Treatment Of Nonferrous Metals Or Alloys (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)
• Heat Treatment Of Articles (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• ing And Chemical Polishing (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=3578468

Family Applications (1)

Country Status (17)

Cited By (5)

Families Citing this family (4)

• 1972
  • 1972-07-03 AT AT567972A patent/AT332133B/de not_active IP Right Cessation
• 1973
  • 1973-02-01 DE DE2305000A patent/DE2305000B2/de not_active Ceased
  • 1973-02-09 YU YU339/73A patent/YU36045B/xx unknown
  • 1973-02-09 HU HUEE2092A patent/HU166564B/hu unknown
  • 1973-02-13 CS CS731043A patent/CS194671B2/cs unknown
  • 1973-02-15 DD DD168886A patent/DD102415A5/xx unknown
  • 1973-02-16 JP JP48019096A patent/JPS526848B2/ja not_active Expired
  • 1973-02-16 IT IT20496/73A patent/IT979200B/it active
  • 1973-02-20 PL PL1973160826A patent/PL84202B1/pl unknown
  • 1973-02-24 ES ES412023A patent/ES412023A1/es not_active Expired
  • 1973-02-26 AU AU52606/73A patent/AU453973B2/en not_active Expired
  • 1973-02-26 ZA ZA731329A patent/ZA731329B/xx unknown
  • 1973-02-26 GB GB938873A patent/GB1367753A/en not_active Expired
  • 1973-02-28 CA CA164,778A patent/CA983357A/en not_active Expired
  • 1973-03-02 FR FR7307494A patent/FR2190939B1/fr not_active Expired
  • 1973-03-02 US US00337687A patent/US3801380A/en not_active Expired - Lifetime
  • 1973-06-20 RO RO7300075192A patent/RO62703A/ro unknown

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