WO2019007309A1 - Environmentally friendly brass alloy for casting and manufacturing method therefor - Google Patents

Abstract

Disclosed are an environmentally friendly brass alloy for casting and a manufacturing method therefor. The brass alloy is free of the elements selenium, tellurium, antimony, phosphorus, magnesium and manganese, and the components thereof are: 58-61.5 wt.% of Cu, ≤ 0.25 wt.% of Pb, 0.5-0.8 wt.% of Al, ＜0.1 wt.% of Sn, ＜0.1 wt.% of Ni, 0.02-0.15 wt.% of Fe, and 5-12 ppm of B, with the balance being Zn and inevitable impurities. In addition to excellent polishing performance and thermal cracking resistance performance, the brass alloy has good comprehensive performance, and is suitable for casting formed bathroom plumbing parts.

Description

Environmentally friendly brass alloy for casting and manufacturing method thereof Technical field

The invention belongs to the technical field of alloys, and particularly relates to a lead-free environmentally-friendly brass alloy for casting which is different from bismuth brass, silicon brass and arsenic brass and does not contain selenium, tellurium, antimony, phosphorus, magnesium and manganese elements. Its manufacturing method.

Background technique

Lead brass contains 1wt.%-4wt.% lead, which is widely used in various fields such as electrical, mechanical and plumbing because of its excellent cutting and forming properties and low cost. However, since lead brass is polluted by the environment during production and use, it is harmful to human health. Developed countries and regions such as the United States, the European Union, and Japan have successively formulated lead-free standards and laws, such as NSF-ANSI61 and NSF-ANSI372. AB-1953, RoHS, etc. Among them, AB-1953 in the United States defines "lead-free" as having a Pb content of no more than 0.25 wt%. China's GB 18145-2014 "ceramic sealing nozzle" also stipulates that the precipitation of lead in drinking water parts should be less than 5ug / L.

In order to achieve lead-free brass, it has been studied to improve the cutting performance of brass alloys by using lead, selenium, tellurium and antimony, and to improve the overall performance of brass alloys by adding appropriate amounts of other elements. The addition of selenium and antimony in brass can effectively improve the cutting performance. However, since selenium and antimony are expensive, it is not easy to be added during the smelting process, and the yield is low, and has not been marketed and industrialized. However, the cockroach itself is toxic. When the Sb content is more than 0.02%, the amount of strontium element dissolved in water by the NSF test will exceed the 0.6μg/L specified in the GB18145-2014 standard and cannot be applied to drinking water system components.

At present, there are three main types of lead-free environmentally-friendly brass that have been widely studied and widely used in the market, namely bismuth brass, silicon brass and arsenic brass, but these types of lead-free environmentally friendly brass have their own defects. In the forming process, bismuth brass is prone to thermal cracking due to Bi, and the welding performance is poor. Because bismuth is associated with lead in the mining process and pollutes the environment, bismuth brass has not been accepted by the European market; The stress corrosion resistance is poor, and the product is prone to stress corrosion failure during use; and the arsenic brass developed to meet the requirements of the Australian anti-zinc removal requirements AS 2345-2006 (the average dezincification depth is not more than 100 μm), the alloy has poor fluidity. The problem of large shrinkage tendency and high casting failure rate.

Phosphorus, magnesium and manganese are added to some brass to improve the properties of brass, but the introduction of these elements has made it difficult to recycle used materials.

Therefore, there is still a need to develop another lead-free environmentally friendly brass alloy which is superior to bismuth brass, silicon brass and arsenic brass and does not contain selenium, bismuth, antimony, phosphorus, magnesium and manganese.

Summary of the invention

In order to overcome the deficiencies of the prior art, the object of the present invention is to provide an environmentally friendly brass alloy which can meet the requirements of lead-free and is different from bismuth brass, silicon brass and arsenic brass, and a preparation method thereof, and also in the brass alloy Contains no selenium, tellurium, antimony, phosphorus, magnesium or manganese.

Another object of the present invention is to provide an environmentally friendly brass alloy having excellent heat crack resistance and a method for preparing the same.

Another object of the present invention is to provide an environmentally friendly brass alloy having good polishing properties and a method of preparing the same.

A further object of the present invention is to provide an environmentally-friendly brass alloy with excellent comprehensive performance and a preparation method thereof, which can be mass-produced, low in cost, good in mechanical properties and casting properties, good in polishing and welding performance, and resistant to thermal cracking. Good, good resistance to stress corrosion.

The object of the present invention is achieved by the following technical solutions.

The invention provides an environment-friendly brass alloy for casting, which has a composition of: 58-61.5 wt.% of Cu, ≤0.25 wt.% of Pb, 0.5-0.8 wt.% of Al, <0.1 wt.% of Sn, <0.1 wt.% of Ni, 0.02-0.15 wt.% of Fe, 5-12 ppm of B, and the balance of Zn and unavoidable impurities.

The content of Cu in the brass alloy is preferably from 59 to 61% by weight.

The content of Al in the brass alloy is preferably from 0.6 to 0.8% by weight, more preferably from 0.65 to 0.75 wt.%.

The content of Pb in the brass alloy is preferably from 0.15 to 0.25 wt.%, and the machinability is good at this time, but it is preferably <0.15 wt.%, more preferably <0.1 wt.%, in order to achieve further lead-free demand. .

The content of Sn in the brass alloy is preferably 0.02 to 0.08 wt.%, more preferably 0.05 to 0.08 wt.%.

The content of Ni in the brass alloy is preferably 0.02 to 0.08 wt.%, or preferably <0.02 wt.%.

The content of Fe in the brass alloy is preferably from 0.03 to 0.08 wt.%.

The content of B in the brass alloy is preferably 5 to 10 ppm, and more preferably 7 to 9 ppm.

The brass alloy has a thermal cracking resistance value of 245 to 400 N, more preferably 350 to 400 N.

The preparation method of the above brass alloy comprises the steps of: weighing brass waste materials, electrolytic copper, Zn, Al, Sn, Ni, Pb and copper-iron intermediate alloy according to the elements contained in the brass alloy and the mass percentage of each element; The content of Cu in the copper-iron intermediate alloy is 90-95 wt.%; an appropriate amount of slag-removing agent is added to the bottom of each furnace before smelting, and then Ni, copper-iron intermediate alloy, brass waste material is added, and the brass waste material is melted. Add 1/4 copper to the surface and add slag to the surface. After all the materials are completely melted, add Zn, Al, Sn, Pb, and mix well. After the metal is completely melted, the slag is heated and then tested. Testing, if necessary, adding a refining agent, after the various indicators are qualified, spitting, standing, and discharging the slag to the ingot; wherein at least one of the brass waste material and the refining agent contains boron.

In the above production method, it is preferred that the slag remover is not borax.

Since the Cu-B master alloy is a high melting point alloy, it is easy to generate a hard spot after the addition, and therefore it is preferable that the additional refiner of the present invention is not a Cu-B master alloy refiner.

Each element added to the alloy of the present invention will be described in detail below.

Adding no more than 0.25 wt.% of lead (Pb) can improve the cutting performance of brass alloys, refine grains, improve casting performance, and meet the lead content of AB1953 for parts and materials in contact with water in drinking water systems. The amount does not exceed 0.25 wt.%, and the lead precipitation in NSF 61 and GB 18145-2014 is less than 5 μg / L.

The addition of aluminum (Al) element can significantly improve the fluidity of the alloy, improve the casting performance, and the effect of solid solution strengthening of Al can improve the strength of the alloy. The Al content should be controlled at 0.5-0.8wt.%, and the Al content is too low. The fluidity of the alloy is not improved obviously, and the product is easy to loosen and leak water, but when the Al content is too high, the fluidity will also decrease.

Iron (Fe) is an essential element of the present invention, mainly plays a role in refining crystal grains. The solubility of Fe in brass structure is very small, and the Fe-rich phase is often present in the matrix to become a crystal nucleus to refine the crystal. Granules, thereby improving the fluidity and casting properties of the alloy. When B is present in the alloy, both Fe and B are combined, and the refining effect is better. The Fe content should be controlled at 0.02-0.15wt.%, Fe<0.02wt.%, and the refining effect is not good. When Fe>0.15wt.%, it is easy to form hard spots and reduce the polishing quality of the alloy.

The main function of boron (B) is to act together with Fe to refine the grains. When B<5ppm, the refining effect on the alloy is not obvious. The inventors have found that hardening often occurs in the process of developing alloys. The problem of poor particle and polishing property, after repeated research, the inventors found that this is because the alloy has a relatively large amount of Fe and B at the same time, in order to maintain a good polishing property, the amount of Fe and B needs to reach a certain balance. When Fe>0.02wt.%, the content of B must be controlled at <12ppm to ensure the polishing quality of the product.

The addition of tin (Sn) element can improve corrosion resistance, improve casting performance and cutting performance, and reduce defects such as pores and porosity in the casting. The Sn content of the present invention should be controlled below 0.1 wt.%, and the alloy becomes brittle when the content of Sn is too high. Casting performance deteriorates.

The addition of nickel (Ni) element can improve the strength, toughness and corrosion resistance of the alloy, and in particular, can enhance the stress corrosion resistance of the brass. The Ni of the present invention should be controlled below 0.1 wt.%, and if it is too high, the cost is increased.

In particular, the brass alloy of the present invention has at least the following beneficial effects as compared with the prior art:

The lead content of the brass alloy of the invention does not exceed 0.25 wt.%, and does not contain elements such as selenium, tellurium and antimony, which meets the requirements of the lead-free law of AB1953, and meets the requirements for the precipitation of metal in water in NSF61 and GB18145-2014. .

The alloy of the invention overcomes the problem that the brass is prone to hot cracking and has poor welding performance; overcomes the problem of poor resistance to stress corrosion of the silicon brass; overcomes the problem that the arsenic brass has poor fluidity and large shrinkage tendency.

The brass alloy of the present invention has good heat crack resistance.

The brass alloy of the present invention has a fine polishing property by blending Fe and B, and has good casting properties while having good casting properties.

The brass of the present invention does not contain elements such as P, Mg, and Mn, and avoids adverse effects caused by elements such as P, Mg, and Mn, and is also convenient for recycling old materials.

The raw material of the alloy of the invention uses brass waste material, has low copper content, low production cost, and has mass production, good mechanical properties and casting performance, good polishing and welding performance, good thermal crack resistance and resistance to stress corrosion. Comprehensive performance with good performance.

The best way to implement the invention

The present invention will be further described in detail below in conjunction with specific embodiments.

Example

The invention is further described in detail below with reference to the specific embodiments, which are set forth to illustrate the invention, but not to limit the scope of the invention.

Example 1 Preparation and Composition Analysis of Alloys and Comparative Alloys of the Invention

A. Preparation and composition analysis of alloy 1-6 of the invention

The alloy 1-6 of the invention is prepared according to the following method: the brass waste material, electrolytic copper, Zn, Al, Sn, Ni, Pb and copper-iron intermediate alloy are weighed according to the mass percentage of the alloy component of the invention, wherein the copper-iron intermediate alloy The content of Cu is 90-95wt.%; an appropriate amount of non-borax slag agent is added to the bottom of each furnace before smelting, and then nickel, copper-iron intermediate alloy, brass waste material is added, and the brass waste material has been melted by 1/4. Add electrolytic copper to the surface. After all the materials are completely melted, add Zn, Al, Sn, Pb, and stir them evenly. After the metal is completely melted, heat up the residue, and then perform component detection and polishing, and if necessary, make up. Add non-CuB alloy refiner, after the various indicators pass, fire, rest, and slag, and heat up to 1050-1100 °C.

The composition of Invention Alloy 1-6 obtained by the above method is shown in Table 1.

B. Comparison or preparation and composition analysis of comparative alloys 1-9

Comparative Alloy 1 was a commercially available lead brass alloy ZCuZn40Pb2, the composition of which is shown in Table 1.

The comparative alloy 2-9 was prepared according to the following general method, and the raw materials used were determined according to the elements contained in the respective comparative alloys: Cu, Si, Zn, Al, Sn, Ni, Pb, Mn, and copper phosphorus were weighed according to the mass percentage of the alloy component. , copper boron, copper-iron intermediate alloy, wherein the content of Cu in the copper boron, copper-iron intermediate alloy is 90wt.%, the content of Cu in the copper-phosphorus intermediate alloy is 85wt.%; Si, Ni is placed on the bottom of the power frequency induction furnace The raw materials of Cu and Zn are placed on Si and Ni, and a refining agent is added, and the temperature is raised to 1050 to 1100 ° C until the materials are all melted, and the surface scum is filtered off; the obtained materials are sequentially added with Al, Sn, Pb, Mn, Stir well to ensure uniform composition; add copper-iron, copper-phosphorus intermediate alloy to the obtained material, stir and stand for 5-10min; add copper-boron intermediate alloy, heat up to 1100～1150°C, fire and keep warm for 5-8min; 1000～1050 After standing at °C, the surface scum is filtered off; the furnace is cooled at 1050~1100 °C.

The compositions of Comparative Alloys 2-9 prepared by the above method are shown in Table 1.

Example 2 Performance Testing of Alloys and Comparative Alloys of the Invention

The properties of the alloy of the present invention and the comparative alloy obtained by the above preparation examples are tested below. The specific performance test items and methods are as follows. The test results are shown in Table 2.

Casting performance

Strip specimen: used to determine the linear shrinkage of the alloy. The lower the linear shrinkage, the stronger the thermal crack resistance of the alloy. The alloy melt was cast on a strip sample mold of length 200 mm at a temperature of 1050 ° C. After cooling, the line shrinkage was calculated by measuring the gap distance between the mold and the alloy sample.

Spiral sample: The alloy melt was cast on a spiral sample mold at a temperature of 1050 ° C, and the flow length of the alloy melt was measured to measure the fluidity of the alloy. The longer the flow length, the better the fluidity of the alloy, the lower the shrinkage tendency of the alloy, and the better the casting performance.

2. Mechanical properties

Tensile properties: According to GB/T228-2010, the tensile strength and elongation of the alloy were tested. The inventive alloy and the comparative alloy were processed into standard specimens with a diameter of 10 mm. Tensile tests were carried out at room temperature to test the alloys. Tensile strength and elongation.

Brinell hardness: According to GB/T231.1-2009, the hardness of the alloy is tested. The round sample of the invention alloy and the comparative alloy is cast, and the two ends are leveled to test the Brinell hardness of each alloy.

3, polishing performance

A 35 mm long piece was sawed in the length direction of the ingot and its cross section was taken. The cross section of the sample was polished by the process (100#-240#-400#-white cloth wheel). The cross section of the polished sample was wiped clean with a dry cloth, and visual inspection was performed under conditions of a luminosity of not less than 300 LX to evaluate the polishing performance. There is a hard spot, which is characterized by poor polishing performance and is represented by "x". No hard spots, showing excellent polishing performance, expressed by "○".

4. Welding performance

The welded parts are low pressure cast castings/CuZn37 brass tubes, brazed, flame heated, and the temperature is 350-400 °C. The weldability evaluation standard is whether cracks and pores appear in the weld and heat affected zone, and no cracks or voids are qualified, which is indicated by “○”; otherwise, it is not qualified, and is represented by “×”.

5. Resistance to thermal cracking

The alloy melt was poured into a thermal cracking shrinkage apparatus at a temperature of 1050 ° C, and its thermal cracking resistance value was measured according to JB/T 4022.2 "Determination of the hot cracking tendency of the alloy casting property measurement method". The higher the thermal cracking resistance value, the smaller the thermal cracking tendency of the alloy.

6. Stress corrosion resistance

Take the same faucet assembly product according to GB/T 10567.2-2007 and YS/T814-2012 for ammonia smoke test. After ammonia smoke, take out the sample, rinse it with water first, then wash it in 5% sulfuric acid solution at room temperature. Corrosion products on the surface of the sample were finally rinsed with water and dried, and the results of ammonia smoking were judged according to the methods described in GB/T 10567.2-2007 and YS/T814-2012, respectively.

7. Metal precipitation in water

The dissolution of the alloying elements of the present invention in water is performed according to the NSF/ANSI 61-2007 standard, and the detector is: Varian 820-MS Icp. Mass Spectrometer (inductively coupled plasma mass spectrometer), the time is 19 days, and the sample is a faucet casting product. , Pb ≤ 5 μg / L, Sb ≤ 0.6 μg / L.

Analysis of results:

The Pb and Sb contents of the metal precipitated in the alloy 1-6 of the invention all meet the requirements of the NSF61 and GB18145-2014 standards. Comparative alloy 1 is a lead-containing brass in which Pb is excessively exceeded, and comparative alloy 4 is a Sb-containing brass in which Sb is excessively precipitated.

The comparative alloy 2-3 is bismuth brass, and their welding performance is unsatisfactory. The welding performance of the alloy 1-6 of the invention is better than that of the comparative alloy 2-3; the linear shrinkage of the alloy 1-6 of the invention is smaller than that of the comparative alloy 2-3 The alloys 1-6 of the present invention have higher thermal cracking resistance values than the comparative alloys 2-3, which indicates that the alloys of the present invention have better thermal cracking resistance than bismuth brass.

Comparative alloy 5-6 is a silicon brass. According to the YS/T814-2012 test, the corrosion corrosion resistance of the comparative alloy 5-6 is unsatisfactory, and the stress corrosion resistance of the alloy 1-6 of the present invention is superior to that of the silicon brass.

The comparative alloy 7 is arsenic brass, and the linear shrinkage and the flowing length of the alloy 1-6 of the invention are obviously superior to those of the comparative alloy 7, that is, the shrinking tendency of the alloy of the invention is significantly smaller than that of the comparative alloy 7, and the casting performance is superior to that of the arsenic brass alloy. The mechanical properties of the alloys 1-6 of the present invention are also significantly better than those of the arsenic brass alloys.

In the comparative alloy 8, since the Fe content is high and the B content is more than 12 ppm, the polishing performance is inferior to that of the inventive alloy 1-6.

The Cu content in Comparative Alloy 9 is higher than the Cu content in the present application, and the overall overall performance of Comparative Alloy 9 is not as good as Alloy 1-6 of the present invention, except for the high manufacturing cost.

In summary, the alloy of the invention meets the requirements of the lead-free law of AB1953, and the amount of metal precipitation in the water meets the requirements of GB18145-2014, overcomes the defects of bismuth brass, silicon brass and arsenic brass, and has good casting performance. Comprehensive properties such as mechanical properties, polishing properties, weldability, stress corrosion resistance, and thermal crack resistance.

As a lead-free environmentally friendly brass alloy, the alloy of the present invention will gradually expand in the application of future drinking water system components.

The above-described embodiments are intended to be illustrative of the present invention, and are not intended to limit the scope of the invention, and any modifications and variations of the present invention are intended to be included within the scope of the present invention.

Claims (10)

An environmentally friendly brass alloy for casting, the composition of which is: 58-61.5 wt.% of Cu, ≤0.25 wt.% of Pb, 0.5-0.8 wt.% of Al, <0.1 wt.% of Sn, <0.1 wt .% Ni, 0.02-0.15 wt.% Fe, 5-12 ppm B, the balance being Zn and unavoidable impurities. The brass alloy according to claim 1, wherein the content of Cu in the brass alloy is 59-61 wt.%; the content of Al is 0.6-0.8 wt%, more preferably 0.65-0.75 wt.%. . The brass alloy according to any one of claims 1 to 2, wherein the content of Pb in the brass alloy is 0.15 to 0.25 wt.%, or <0.15 wt.%, preferably <0.1. Wt.%. The brass alloy according to any one of claims 1 to 3, wherein the content of Sn in the brass alloy is 0.02 to 0.08 wt.%, preferably 0.05 to 0.08 wt.%. The brass alloy according to any one of claims 1 to 4, wherein the content of Ni in the brass alloy is 0.02-0.08 wt.%, or <0.02 wt.%. The brass alloy according to any one of claims 1 to 5, wherein the content of Fe in the brass alloy is 0.03 - 0.08 wt.%. The brass alloy according to any one of claims 1 to 6, wherein B in the brass alloy is 5 to 10 ppm, more preferably 7 to 9 ppm. The brass alloy according to any one of claims 1 to 7, wherein the brass alloy has a thermal cracking resistance value of 245 to 400 N, more preferably 350 to 400 N. A method of producing a brass alloy according to any one of claims 1-8, comprising the steps of: According to the element contained in the brass alloy and the mass percentage of each element, the brass waste material, electrolytic copper, Zn, Al, Sn, Ni, Pb and copper-iron intermediate alloy are obtained, wherein the content of Cu in the copper-iron intermediate alloy is 90. -95wt.%; Add a proper amount of slag remover to the bottom of each furnace before smelting, then add Ni, copper-iron intermediate alloy, brass waste material, and add electrolytic copper and slag to the surface when the brass waste material has been melted by 1/4. After complete melting, add Zn, Al, Sn, Pb in turn, and stir well. After the metal is completely melted, heat the residue, then carry out component detection and performance testing. If necessary, add refiner. After the indicators are qualified, spray. Fire, rest, and slag are discharged into the ingot; Wherein at least one of the brass waste material and the refiner contains boron. A method of producing a brass alloy according to claim 9, wherein the slag removing agent is not borax, and the additional refining agent is not a Cu-B intermediate alloy refining agent.