Preparation method of low-copper high-strength brass strip for household appliance connector

Abstract

The invention discloses a preparation method of a low-copper high-strength brass strip for a household appliance connector. The preparation method comprises the following steps: (1) smelting an alloy comprising 59-62 wt% of Cu, 0.8-1.2 wt% of Sn, 0.3-0.8 wt% of Fe, 0.2-0.6 wt% of Ni, 0.01-0.05 wt% of P and the balance of Zn and inevitable impurities; (2) after a cast ingot is obtained through semi-continuous casting, homogenization treatment is conducted for 4-6 h at the temperature of 680-720 DEG C; and (3) the initial rolling temperature of hot rolling is controlled to be 650 + / -10 DEG C, the final rolling temperature is controlled to be larger than or equal to 480 DEG C, and the total reduction rate is 85-90%. According to the preparation method of the low-copper and high-strength brass strip for the household appliance connector, through Cu-Zn-Sn-Fe-Ni-P component system design and cooperation with the specific homogenization treatment-multi-pass temperature control hot rolling-double-stage cold rolling annealing process, under the condition that the copper content is reduced to 59-62%, the tensile strength is larger than or equal to 500 MPa, the electric conductivity is larger than or equal to 25% IACS, and the ductility can stably reach 10-15%. The grain size of the product reaches ASTM12 level or above, the bending performance R / t is equal to 0, no crack is generated, the lead content meets the RoHS3.0 standard, the comprehensive cost is reduced by 18-22%, and the high-end electric appliance connector is particularly suitable for being plugged and unplugged for 50 thousand times.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of non-ferrous metal processing, in particular to a preparation method of low-copper high-strength brass strip for household appliance connectors. BACKGROUND

[0002] Traditional household appliance connectors usually use H65 and H70 brass (copper content 65-70 wt%), which has the following defects:

[0003] 1. Large copper resource consumption, material cost accounting for more than 60%

[0004] 2. Insufficient strength (tensile strength < 400 MPa), easy to deform after multiple plugging and unplugging

[0005] 3. High lead content (> 0.1 wt%), not meeting the RoHS 3.0 environmental protection requirement

[0006] The existing copper reduction scheme adopts adding excessive Al and Si to improve the strength, but leads to:

[0007] 1. Conductivity reduction of more than 30%

[0008] 2. High hot rolling cracking rate of 15%

[0009] 3. "Orange peel" phenomenon during bending processing. SUMMARY

[0010] The application aims to provide a preparation method of low-copper high-strength brass strip for household appliance connectors, so as to solve the problems of the preparation method of low-copper high-strength brass strip for household appliance connectors in the market at present.

[0011] To achieve the above-mentioned purpose, the application provides the following technical scheme: a preparation method of low-copper high-strength brass strip for household appliance connectors, comprising the following steps:

[0012] (I): smelting an alloy with the following components: Cu 59-62 wt%, Sn 0.8-1.2 wt%, Fe 0.3-0.8 wt%, Ni 0.2-0.6 wt%, P 0.01-0.05 wt%, and the balance being Zn and inevitable impurities;

[0013] (II): after semi-continuous casting to obtain an ingot, performing 680-720 DEG C / 4-6 h homogenization treatment;

[0014] (III): controlling the hot rolling opening rolling temperature to be 650 DEG C ± 10 DEG C, the final rolling temperature to be greater than or equal to 480 DEG C, and the total reduction rate to be 85-90%;

[0015] (IV) Cold rolling in two stages: the first stage is annealed at 460±10℃ after 40-50% deformation, and the second stage is annealed at 280±10℃ after 60-70% deformation.

[0016] Preferably, the hot rolling is performed in 9-11 passes, with the first pass reduction being ≤25%.

[0017] Preferably, the second stage annealing time of cold rolling is 20-40 minutes.

[0018] Preferably, the surface treatment uses a chromium-free passivation solution containing 5-10 g / L of titanate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The preparation method of the brass strip for home appliance connectors with low copper content and high strength is to form a nanoscale (Cu,Fe)3P strengthening phase by controlling the Cu / Zn ratio (0.95-1.05) and combining it with Sn-Fe-Ni microalloying. The P content is precisely controlled to make the grain size ≤8μm.

[0021] (2) The preparation method of the brass strip for home appliance connectors with low copper content and high strength adopts the strategy of "high temperature rapid rolling + final rolling temperature control" for hot rolling to suppress the precipitation of β phase, and innovatively adopts the process of "large deformation + low temperature short time annealing" in the cold rolling stage, with a dislocation density of 10 14 m -2 . DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Example 1:

[0024] A method for preparing low-copper, high-strength brass strip for home appliance connectors. The following details the production and application of the above-mentioned method:

[0025] 1. Alloy smelting:

[0026] 1. Ingredients by mass percentage: Cu 59-62%, Sn 0.8-1.2%, Fe 0.3-0.8%, Ni 0.2-0.6%, P 0.01-0.05%, the balance is Zn and unavoidable impurities;

[0027] 2. Use industrial frequency induction furnace for smelting, cover the melt surface with charcoal layer, and control the melting temperature at 1080±20℃.

[0028] II. Semi-continuous casting:

[0029] 1. Casting speed 80-120 mm / min;

[0030] 2. Cooling water pressure 0.15-0.25 MPa;

[0031] 3. Obtaining a cast ingot with a cross-section of 220 x 620 mm.

[0032] III. Homogenization treatment:

[0033] 1. Heating to 680-720 °C for 4-6 h;

[0034] 2. Water quenching after furnace cooling to 500 °C.

[0035] IV. Hot rolling process:

[0036] 1. Opening rolling temperature 650 ± 10 °C, finishing rolling temperature ≥ 480 °C;

[0037] 2. Total reduction 85-90%, completed in 9-11 passes;

[0038] 3. Reduction in the first pass ≤ 25%.

[0039] V. Cold rolling-annealing synergistic control:

[0040] 1. First cold rolling: deformation 40-50% → intermediate annealing (460 ± 10 °C / 2 h);

[0041] 2. Second cold rolling: deformation 60-70% → stress relief annealing (280 ± 10 °C / 30 min).

[0042] VI. Surface treatment:

[0043] 1. Alkaline washing (NaOH 80 g / L, 60 °C) → acid washing (H2SO4 10% + H2O2 3%, 40 °C);

[0044] 2. Titanium-based chromium-free passivation treatment.

[0045] Example 2:

[0046] A method for producing a low-copper high-strength brass strip for household appliance connectors is described below, and the production and its application are described in detail:

[0047] I. Ingredients: Cu 60.5%, Sn 1.0%, Fe 0.5%, Ni 0.4%, P 0.03%, Zn balance.

[0048] II. After smelting, the cast ingot is homogenized at 700 °C for 5 h.

[0049] 3. Hot rolling: starting rolling temperature is 650℃, finishing rolling temperature is 485℃, and the total reduction rate is 88%.

[0050] 4. Cold rolling: first pass 45% deformation → 460℃ / 2h annealing → second pass 65% deformation → 280℃ / 30min annealing.

[0051] 5. Final strip thickness 0.25mm.

[0052] Performance Test Table

[0053]

[0054] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-copper, high-strength brass strip for home appliance connectors, characterized in that: The following steps are involved: (1) Melting an alloy with a composition of 59-62 wt% Cu, 0.8-1.2 wt% Sn, 0.3-0.8 wt% Fe, 0.2-0.6 wt% Ni, 0.01-0.05 wt% P, and the balance being Zn and unavoidable impurities; (2) After the ingot is obtained by semi-continuous casting, it is subjected to homogenization treatment at 680-720℃ / 4-6h; (3): Control the hot rolling starting temperature at 650±10℃, the final rolling temperature at ≥480℃, and the total reduction rate at 85-90%; (IV) Cold rolling in two stages: the first stage is annealed at 460±10℃ after 40-50% deformation, and the second stage is annealed at 280±10℃ after 60-70% deformation.

2. The method for preparing a low-copper, high-strength brass strip for home appliance connectors according to claim 1, characterized in that: The hot rolling is performed in 9-11 passes, with the first pass reduction ratio being ≤25%.

3. The method for preparing a low-copper, high-strength brass strip for home appliance connectors according to claim 1, characterized in that: The second stage annealing time of cold rolling is 20-40 minutes.

4. The method for preparing a low-copper, high-strength brass strip for home appliance connectors according to claim 1, characterized in that: The surface treatment adopts a chromium-free passivation solution containing 5-10 g / L of titanate.

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