Copper alloys for use as connector materials having high resistance to stress corrosion cracking and a process for producing the same
AssigneeDowa Mining Co., Ltd.
InventorsLe Ling, Akira Sugawara
Life of this patent
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Abstract
The improved copper alloy suitable for use as a connector material contains 17-32 wt % of Zn, 0.1-4.5 wt % of Sn and 0.01-2.0 wt % of Si, with Zn and Sn satisfying the relation 54≦3X+Y≦100 where X is the amount in wt % of Zn added and Y is the amount in wt % of Sn added. Rolled material of the alloy can be produced by a process comprising the steps of melting a copper alloy of the composition specified above, cooling the melt over a temperature range from the liquidus line to 600° C. at a rate of at least 50° C./min, and subsequently hot rolling the resulting ingot at an elevated temperature of 900° C. or below.
Claims14
A copper alloy for use as a connector material having high resistance to stress corrosion cracking that contains 17-32 wt % Zn, Sn and Si, with the balance being copper and incidental impurities, and which has resistance to stress corrosion cracking such that its stress cracking life in a 3% NH3 atmosphere is at least five times as long as the value for class 1 brass.
A copper alloy for use as a connector material having high resistance to stress corrosion cracking that contains 17-32 wt % Zn, Sn and Si, with the balance being copper and incidental impurities, which has resistance to stress corrosion cracking such that its stress cracking life in a 3% NH3 atmosphere is at least five times as long as the value for class 1 brass, and which has a 0.2 wt % yield strength of at least 600 N/mm2, a tensile strength of at least 650 N/mm2, an electrical conductivity of at least 20 % IACS, a Young's modulus of no more than 120 kN/mm2 and a percent stress relaxation of no more than 20%, each in rolling direction.
A copper alloy for use as a connector material having high resistance to stress corrosion craking that contain 17-32 wt % Zn, 0.1-4.5 wt % Sn and 0.01-2.0 wt % Si, with the balance being copper and incidental impurities, provided that Zn and Sn satisfy the following relation (1):
- 54≦3X+Y≦100 (1)
- where X is the amount in wt % of Zn added and Y is the amount in wt % of Sn added, which has resistance to stress corrosion cracking such that its stress cracking life in a 3% NH3 atmosphere is at least five times as long as the value for class 1 brass, and which has a 0.2 wt % yield strength of at least 600 N/mm2, a tensile strength of at least 650 N/mm2, an electrical conductivity of at least 20% IACS, a Young's modulus of no more than 120 kN/mm2 and a percent stress relaxation of no more than 20% in the direction where said alloy was wrought whereas it has a 0.2% yield strength of at least 650 N/mm2, a tensile strength of at least 700 N/mm2 and a Young's modulus of no more than 130 kN/mm2 in a direction perpendicular to said first direction.
A process for producing a copper alloy for use as a connector material having high resistance to stress corrosion cracking which comprises the steps of:
- melting a copper alloy that contains 17-32 wt % Zn, Sn and Si, with the balance being copper and incidental impurities;
- cooling the melt over a temperature range from the liquidus line to 600° C. at a rate of at least 50° C./min;
- and
- subsequently hot rolling the resulting ingot at an elevated temperature of 900° C. or below.
A process for producing a copper alloy for use as a connector material having high resistance to stress corrosion cracking which comprises the steps of:
- melting an alloy that contains 17-32 wt % Zn, 0.1-4.5 wt % Sn and 0.01-2.0 wt % Si, with the balance being copper and incidental impurities, provided that Zn and Sn satisfy the following relation (1),:
- 54≦3X+Y≦100 (1)
- where X is the amount in wt % of Z added and Y is the amount in wt % of Sn added;
- cooling the melt over a temperature range from the liquidus line to 600° C. at a rate of a,:
- least 50° C./min;
- subsequently hot rolling the resulting ingot at an elevated temperature of 900° C. or below;
- and
- repeating the process of cold rolling and annealing in a temperature range of 300-650° C. until the as-annealed rolled material has a crystal grain size of no more than 10 μm.
A process for producing a copper alloy for use as a connector material having high resistance to stress corrosion cracking which comprises the steps of:
- melting an alloy that contains 17-32 wt % Zn, 0.1-4.5 wt % Sn and 0.01-2.0 wt % Si, with the balance being Cu and incidental impurities, provided that 2n and Sn satisfy the following relation (l):
- 54≦3X+Y≦100 (1)
- where X is the amount in wt % of Zn added and Y is the amount in wt % of Sn added;
- cooling the melt over a temperature range from the liquidus line to 600° C. at a rate of at least 50° C./min;
- subsequently hot rolling the resulting ingot at an elevated temperature of 900° C. or below;
- repeating the process of cold rolling and annealing in a temperature range of 300 -650° C. until the as-annealed rolled material has a crystal grain size of no more than 10 μm;
- and
- further performing rolling for a reduction ratio of at least 30% and low-temperature annealing at 450° C. or below so that the rolled material has a stress corrosion cracking property such that the corrosion cracking life in a 3% NH3 atmosphere is at least five times as long as the value for class 1 brass, and that it has a 0.2% yield strength of at least 600 N/mm2, a tensile strength of at least 650 N/mm2, a Young's modulus of no more than 120 kN/mm2, an electrical conductivity of at least 20% IACS and a percent stress relaxation of no more than 20% in the direction where said alloy was wrought whereas the alloyed material has a 0.2% yield strength of at least 650N/mm2, a tensile strength of at least 700 N/mm2 and a Young's modulus of no more than 130 kN/mm2 in a direction perpendicular to said first direction.
Dependencies are inferred from the claim text.