New Copper Alloys - Winter 1998 Notes from CDA's Technical Service Advisory Committee December, 1998 Meeting
Copper Applications in Innovative Technology
Several new alloy registrations were completed during Copper Development Association Inc.'s Technical Service and Standards Advisory Committee, Winter meeting. Adjustments were also made to three existing alloys, and a group of the bismuth casting alloys were activated after wording of the related footnote (54) was resolved.
New UNS Alloy No. C19720 was assigned to the Olin Brass high copper strip alloy being introduced into the electrical terminal and springs application group. Of particular interest is its stress relaxation characteristic. High contact force retention during prolonged exposure to as high as 300 F, and electrical conductivity of 80 % IACS are, reportedly, major areas for consideration in application selection. The alloy is available in the HR02 and HR04 cold rolled and stress relieved tempers, with nominal yield strengths of 48 and 60 ksi, respectively.
Two new copper-nickel alloys were added at the request of The Miller Company. Alloy Nos. C70280 and C70290 were assigned. Both are precipitation heat treatable strip alloys, and are being directed at the higher strength, electrical and electronic connector and spring areas. Electrical conductivity of 40 and 30 % IACS, respectively, and good formability are listed as significant characteristics. Alloy C70280 is available as TH04 temper, with a typical YS of 65 ksi., TH06 - YS 75 ksi., and TH08 - YS 100 ksi. Alloy C70290 is available as TH04 - typical YS 75 ksi., TH06 - YS 85 ksi., and TH08 - YS 95 ksi.
Changes in Alloy Registrations
At the request of Waterbury Rolling Mills, the registered Alloy No. C42510 assigned during the Summer meeting, was changed to C42220 to better align the composition with the other alloys in the group and reflect the alloy from which it was derived. All chemical, physical and mechanical data remain as previously registered.
The Outokumpu American Brass request to adjust the composition of Alloy No. C70260 from a phosphorus of 0.005 to 0.010%, was accepted. They requested the original registration four years ago. Mechanical and physical properties of the alloy are not effected by this change.
Footnote (35) in the "Application Data Sheet, Standard Designations for Wrought and Cast Copper and Copper Alloys" indicates "The additional maximum limits shall apply: When the product is for subsequent welding applications�". Ansonia Copper & Brass, Inc. submitted a request that the footnote no longer be applied to Alloy Nos. C70600 and C71500. The rationale was that the footnote became redundant, after alloys C70620 and C71520 were registered at the request of Naval Sea Systems Command (in 9/97 as part of the planned replacement of Mil-C-24679 by an ASTM document). C70620 and C71520 are discrete welding application versions of alloys of C70600 and C71500. The request to adjust the alloy registration was accepted.
The bismuth containing, plumbing fitting, casting alloys, Nos. C89325, C89831, C89833, C89835, and C89837, registered by The Federal Metal Company which had been placed in the inactive category, pending resolution of the wording of footnote (54), were replaced in the active category. Footnote 54 will now appear as follows:
(54) .01 - 2.0% as any single or combination of Ce, La or other rare earth* elements, as agreed upon. * ASM International definition: One of the group of 15 chemically similar metals with atomic numbers 57 through 71, commonly referred to as lanthanides.
The new edition of the "Application Data Sheet, Standards Designations for Wrought and Cast Copper and Copper Alloys" including these Winter meeting additions and updates, is due to be published early in 1999.
UNS Alloy No. Registration Request Procedure
Some concern has been noted about the specific CDA procedure for registering compositions in the UNS numbering system. It was reemphasized, in the meeting, that the procedure on page 1 of the "Application Data Sheet, Standard Designations for Wrought and Cast Copper and Copper Alloys" lists the three requirements applied to all requests. An addendum will be issued to the effect that a complete data sheet is a requisite for registration. An additional item will be added requesting that the originator suggest a registration number, and their rationale for that number.
A deadline for requests prior to each meeting will be published, to allow adequate time for review and consideration of the requests. The procedure, deadline date, and blank data sheet will be posted on the Copper Page, Web Site, in the near future. Blank data sheets, as well as any CDA publications, are available from the CDA New York publication desk.
ASME Boiler and Pressure Vessel Code Activity
(from A. Kireta Jr. report)
The stress reduction factor used to develop the allowable stress for materials governed by Ultimate Tensile Strength has been reduced from 4 to 3.5. This will result in an increase in allowable stresses for materials in the temperature regime where the stresses are governed by time independent properties (UTS). However, this will not effect temperature regimes governed by either yield stress or time dependent properties (creep or stress-rupture). Fortunately for many of the copper alloys of hard-drawn temper, their allowable stresses are governed by time independent properties and will benefit from this change. As an example, C12200, hard drawn copper tube, internal pressure rating will increase approximately 12%. Annealed tempers of the majority of the alloys will not benefit from an increase since yield stress tends to control.
ASME also using the data developed to update the yield stress table (Y-1) for yield stresses of all materials at temperature.
Efforts are currently underway to review and combine data on the thermal expansion and other physical properties of copper alloys at varying temperatures to produce Tables for use in all of the B31 codes.
Also in this Issue:
- New Life for Old Boards
- Copper Busbar Sizing Guide
- New Copper Alloys - Winter 1998 Notes from CDA's Technical Service Advisory Committee December, 1998 Meeting