Preparation method of environment-friendly copper alloy wire for screws

Abstract

The invention discloses a preparation method of a copper alloy wire for an environment-friendly screw. The preparation method comprises the following steps: 1) smelting alloys in percentage by weight: 85-92% of Cu, 5-8% of Sn, 0.5-1.5% of Si, 0.1-0.5% of Fe, 0.01-0.1% of P, 0.01-0.1% of rare earth and less than or equal to 0.01% of Pb; (2) performing semi-continuous casting after vacuum melting; (3) homogenizing annealing at 650 DEG C for 4 hours; (4) performing hot rolling to phi 12mm, and performing cold rolling to phi 5.0 mm; (5) carrying out solid solution at 750 DEG C for 30 minutes and aging at 350 DEG C for 2 hours; and (6) carrying out electrolytic polishing until Ra is less than or equal to 0.2 mu m. According to the preparation method of the environment-friendly copper alloy wire for the screw, lead is replaced with an Sn-Si-Fe composite strengthening system, the strength and formability are both considered, the porosity of rare earth elements is reduced by 30%, the density is improved, meanwhile, energy consumption is reduced by 40% while precipitation strengthening is guaranteed, and 300 DEG C * 10 min stress relief annealing is added between cold rolling passes, so that cracks are prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper alloy wire, in particular to a preparation method of an environmentally friendly copper alloy wire for screws. BACKGROUND

[0002] Copper alloy is an alloy composed of pure copper as the matrix and one or more other elements. Pure copper is purple red, also known as red copper. Commonly used copper alloys are divided into three categories: brass, bronze, and white copper.

[0003] The existing copper alloy wire for screws has the following problems during preparation:

[0004] 1. Oxidation during smelting process, leading to composition segregation;

[0005] 2. Large residual stress after cold working, affecting the fatigue resistance of the screw;

[0006] 3. High energy consumption of traditional aging treatment, and grain coarsening reduces strength. SUMMARY

[0007] The present application aims to provide a preparation method of an environmentally friendly copper alloy wire for screws to solve the problems mentioned above.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solution: a preparation method of an environmentally friendly copper alloy wire for screws, comprising the following steps:

[0009] Step 1: Alloy composition design (weight percentage)

[0010] Copper (Cu): 85-92%

[0011] Tin (Sn): 5-8% (strengthening phase formation)

[0012] Silicon (Si): 0.5-1.5% (deoxidizing, improving fluidity)

[0013] Iron (Fe): 0.1-0.5% (grain refinement)

[0014] Phosphorus (P): 0.01-0.1% (deoxidizer)

[0015] Rare earth elements (Ce / La): 0.01-0.1% (melt purification)

[0016] Environmental requirements: lead (Pb) ≤0.01%, cadmium (Cd) ≤0.001%, and the rest are unavoidable impurities.

[0017] Step 2: Preparation process

[0018] 1. Vacuum smelting:

[0019] The copper ingot is smelted under the protection of argon, Sn, Fe and Si are sequentially added, and P-Cu intermediate alloy is finally added;

[0020] The smelting temperature is 1150-1200 DEG C, the rare earth element is added after 20 min of heat preservation.

[0021] II. Semi-continuous casting:

[0022] The pouring temperature is 1080-1100 DEG C, the cooling water flow is 30-50 m 3 / h, and the Φ80mm ingot is cast.

[0023] III. Homogenization treatment:

[0024] 650 DEG C * 4h annealing, eliminating dendritic segregation.

[0025] IV. Hot rolling + cold rolling:

[0026] Hot rolling to Φ12mm (850 DEG C * 1h);

[0027] Multi-pass cold rolling to Φ5.0mm, and the cumulative deformation is 70%.

[0028] V. Solid solution aging:

[0029] Solid solution: 750 DEG C * 30 min water quenching;

[0030] Aging: 350 DEG C * 2h air cooling, and the nanoscale Cu3Sn strengthening phase is precipitated.

[0031] VI. Surface treatment:

[0032] The oxidation layer is removed by electrolytic polishing, and the surface roughness Ra is less than or equal to 0.2 mu m.

[0033] Compared with the prior art, the beneficial effects of the present application are:

[0034] (1) The preparation method of the environment-friendly copper alloy wire for screws, by replacing lead with Sn-Si-Fe composite strengthening system, the strength and formability are considered, and the rare earth element reduces the porosity by 30%, and the density is improved.

[0035] (2) The preparation method of the environment-friendly copper alloy wire for screws, while ensuring the precipitation strengthening, the energy consumption is reduced by 40%, and 300 DEG C * 10 min stress relief annealing is added between cold rolling passes to prevent cracks. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0037] Embodiment one:

[0038] A preparation method of an environment-friendly copper alloy wire rod for screws is provided, and the production and application thereof are described in detail as follows.

[0039] Step 1: alloy component design (weight percentage)

[0040] Copper (Cu): 85-92%

[0041] Tin (Sn): 5-8% (strengthening phase generation)

[0042] Silicon (Si): 0.5-1.5% (deoxidation, improve fluidity)

[0043] Iron (Fe): 0.1-0.5% (grain refinement)

[0044] Phosphorus (P): 0.01-0.1% (deoxidizer)

[0045] Rare earth elements (Ce / La): 0.01-0.1% (melt purification)

[0046] Environmental protection requirements: lead (Pb) ≤0.01%, cadmium (Cd) ≤0.001%, and the rest is unavoidable impurities.

[0047] Step 2: preparation process

[0048] I. Vacuum melting:

[0049] Melt the copper ingot under argon protection, add Sn, Fe, Si in sequence, and finally add P-Cu intermediate alloy;

[0050] Melting temperature: 1150-1200℃, add rare earth elements after holding for 20 min.

[0051] II. Semi-continuous casting:

[0052] Pouring temperature: 1080-1100℃, cooling water flow rate: 30-50m 3 / h, cast Φ80mm ingot.

[0053] III. Homogenization treatment:

[0054] 650℃×4h annealing, eliminate dendritic segregation.

[0055] Four, hot rolling + cold rolling:

[0056] Hot rolling to Φ12mm (850℃x1h);

[0057] Multi-pass cold rolling to Φ5.0mm, cumulative deformation 70%.

[0058] Five, solution and aging:

[0059] Solution: 750℃x30min water quenching;

[0060] Aging: 350℃x2h air cooling, precipitating nanoscale Cu3Sn strengthening phase.

[0061] Six, surface treatment:

[0062] Electrolytic polishing to remove oxide layer, surface roughness Ra≤0.2μm.

[0063] Example two:

[0064] A production method of an environment-friendly copper alloy wire for screws is described below, and the production and application thereof are described in detail:

[0065] Component proportion: Cu 89.5%, Sn 7.0%, Si 1.0%, Fe 0.3%, P 0.05%, Ce 0.05%

[0066] Performance results:

[0067] Tensile strength: 625MPa;

[0068] Electrical conductivity: 45%IACS;

[0069] Cold heading formability (5 times diameter): no cracking;

[0070] Salt spray test (96h): corrosion rate <0.002mm / year.

[0071] It is also to be noted that the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusions, such that a process, method, product, or apparatus that comprises a list of elements does not include only those elements in the list, but can also include other elements not expressly listed, or can also include elements inherent in such process, method, product, or apparatus. Without further limitation, an element preceded by "comprises a" does not exclude the existence of additional identical elements in the process, method, product, or apparatus including the element.

[0072] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalent features, by those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an environmentally friendly copper alloy wire for screws, characterized in that, Includes the following steps: (I): Alloy smelting by weight percentage: Cu 85-92%, Sn 5-8%, Si 0.5-1.5%, Fe 0.1-0.5%, P 0.01-0.1%, rare earth 0.01-0.1%, Pb≤0.01%; (II): Semi-continuous casting after vacuum melting; (III): Homogenization annealing at 650℃ for 4 hours; (iv): Hot-rolled to Φ12mm, cold-rolled to Φ5.0mm; (V): Solution treatment at 750℃ for 30 min + aging at 350℃ for 2 h; (vi): Electropolishing until Ra≤0.2μm.

2. The method for preparing an environmentally friendly copper alloy wire for screws according to claim 1, characterized in that: The rare earth element is either cerium (Ce) or lanthanum (La).

3. The method for preparing an environmentally friendly copper alloy wire for screws according to claim 1, characterized in that: The cold rolling process includes an additional stress-relief annealing process at 300°C for 10 minutes between passes.

4. The method for preparing an environmentally friendly copper alloy wire for screws according to claim 1, characterized in that: The wire is suitable for manufacturing high-strength screws of grade 8.8 and above.