Process method for refining grain size of hot-working structure of copper-zinc alloy

Abstract

The invention belongs to the technical field of non-ferrous metal processing, and discloses a process method for refining the grain size of a hot-working structure of a copper-zinc alloy, which comprises the following steps of: inspecting the appearance of a copper-zinc alloy cast ingot; homogenizing annealing is carried out in a nitrogen or CO2 atmosphere containing trace oxygen, the heating temperature is 750-850 DEG C, the heating time is 4-10 hours, and heat preservation is carried out for 3-8 hours; surface oxide skin is removed after annealing, hot rolling is conducted, the hot rolling temperature is controlled to be 300-450 DEG C, and the total machining rate is larger than or equal to 90%; and finally, detecting the grain size. By optimizing homogenizing annealing and hot rolling process parameters, the grain size of the copper-zinc alloy is reduced to 0.045-0.070 mm from 0.150-0.180 mm, the comprehensive performance of the material is remarkably improved, meanwhile, the phenomena of oxidation and dezincification are effectively reduced, the occurrence rate of defects such as peeling and edge cracking is reduced, the yield is increased to 99.7% or above, the technological process is simple and efficient, energy consumption is low, and the method is suitable for industrial production. The method has the advantages of good economic benefits and environmental protection.

Description

Technical Field

[0001] The invention relates to the field of nonferrous metal processing, and in particular to a process method for refining the grain size of a copper-zinc alloy thermal processing structure. Background Art

[0002] Ordinary brass is widely used in instruments, sanitary ware, plumbing equipment, hydraulic valves, etc. due to its good mechanical properties and processing properties. Copper-zinc binary alloy is called ordinary brass or simple brass, which can be divided into three categories according to its organization: α brass (single-phase brass, zinc content is less than 36%), α+β duplex brass (zinc content is 36% to 46.5%) and β brass (zinc content is 46.5% to 50%, mainly used as solder).

[0003] In the prior art, the crystal spacing of α brass and α+β brass is relatively narrow, and coarse columnar crystal structures are easily formed during the casting solidification process. Although heating the ingot before hot rolling can improve the plasticity of the ingot, eliminate segregation structure, and achieve a state of balanced crystallization, it is worth noting that all brasses have a brittle zone between 200°C and 900°C, and this brittle zone will change its temperature range with different zinc content. In this brittle zone, the main problem of the material is coarse grains. During the hot working process, if this temperature range cannot be avoided, it is easy to cause hot working brittleness due to coarse grains, and then quality problems such as peeling and cracking will occur.

[0004] Therefore, how to effectively refine the grain size of the hot-working structure of copper-zinc alloy, avoid quality defects during processing, and improve product performance has become a technical problem that needs to be solved in this field. Developing a process method that can refine the grain size of the hot-working structure of copper-zinc alloy is of great significance to improving the production quality and application performance of copper-zinc alloy products. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the existing copper-zinc alloy hot processing technology, solve the problems of coarse grains, peeling, cracking, etc. during hot rolling, and at the same time improve the formability, uniformity and comprehensive performance of copper-zinc alloy plates to meet the needs of industrial mass production. A process method for refining the grain size of the hot processing organization of copper-zinc alloy is provided. By optimizing the key process steps such as ingot heating, homogenization annealing, hot rolling and dynamic recrystallization, the uniformity of the organization and performance of the hot-rolled strip is ensured, and high-quality production of copper-zinc alloy plates is achieved.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A process for refining the grain size of a copper-zinc alloy hot-working structure comprises the following steps:

[0008] Carry out appearance inspection on copper-zinc alloy ingots, remove bad gate defects, and ensure that there are no loose or crack defects on the surface;

[0009] In nitrogen or CO containing trace amounts of oxygen 2 In the atmosphere, the ingot is homogenized and annealed in a walking beam heat treatment furnace, the heating temperature is controlled at 750-850°C, the heating time is 4-10 hours, and the holding time is 3-8 hours;

[0010] After the ingot is annealed and taken out of the furnace, the surface oxide scale is removed by a high-pressure spray gun, and hot rolling is carried out. The hot rolling temperature is controlled at 300-450℃, and the total processing rate of the hot-rolled strip is ≥90%;

[0011] The hot-rolled billet was sampled and tested for grain size analysis.

[0012] As a process method for refining the grain size of a hot-working structure of a copper-zinc alloy according to the present invention, further, the walking-beam heat treatment furnace gradually transfers the ingot by the rising, advancing, descending and retreating actions of a water-cooled metal beam, and adopts a side-in and side-out loading and unloading method.

[0013] As a process method for refining the grain size of a hot-working structure of a copper-zinc alloy according to the present invention, further, the hot rolling is performed in 9 passes.

[0014] As a process method for refining the grain size of a copper-zinc alloy hot-working structure according to the present invention, further, the thickness of the copper-zinc alloy ingot is 210 mm-260 mm.

[0015] As a process method for refining the grain size of the hot-working structure of the copper-zinc alloy of the present invention, further, water spray cooling is performed on the hot rolling roller after hot rolling.

[0016] As a process method for refining the grain size of the hot-working structure of a copper-zinc alloy according to the present invention, further, the hot-rolled product is subjected to surface and edge milling on a double-sided milling machine, the milling cutter speed is 700-900 r / min, and the milling speed is 8-20 m / min.

[0017] As a process method for refining the grain size of a hot-working structure of a copper-zinc alloy of the present invention, further, the copper-zinc alloy is an H70 alloy, the heating temperature is 790-810°C, the heating time is 5.5-7.5 hours, the insulation time is 4.5-6.5 hours, and the hot rolling temperature is 370°C.

[0018] As a process method for refining the grain size of a hot-working structure of a copper-zinc alloy of the present invention, further, the copper-zinc alloy is an H65 alloy, the heating temperature is 780-800°C, the heating time is 5.5-7.5 hours, the insulation time is 4.5-6.5 hours, and the hot rolling temperature is 350°C.

[0019] The beneficial effects of the present invention are:

[0020] The present invention innovatively adopts a method combining step-by-step homogenization annealing with hot rolling process to significantly refine the grain structure of the copper-zinc alloy, and the grain size is reduced from 0.150mm-0.180mm in the original process to 0.045mm-0.070mm, which significantly improves the comprehensive performance of the material; at the same time, by optimizing the annealing atmosphere, using nitrogen or CO containing trace oxygen 2 atmosphere, effectively reducing oxidation and dezincification, and improving the surface quality of the ingot; strictly controlling the temperature range (300°C-450°C) during hot rolling, avoiding the problem of coarse grains in the brittle zone, reducing the incidence of defects such as peeling and cracking, and increasing the yield rate to more than 99.7%; in addition, the process of the invention is suitable for copper-zinc alloy ingots of different specifications and zinc contents, has strong applicability and industrial promotion value, and has a simple and efficient process flow, low energy consumption, and good economic benefits and environmental protection advantages. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0022] Embodiment 1:

[0023] This embodiment uses H65 copper-zinc alloy ingots with specifications of 210mm×620mm×6m, and the technical requirements are as follows:

[0024] Brand-state: H65-R

[0025] Finished product specifications: 14.5mm×672mm

[0026] Performance requirements: grain size ≤ 0.08mm

[0027] The specific process steps are as follows:

[0028] (1) Perform an appearance inspection on the H65 copper-zinc alloy ingot to ensure that there are no defects such as looseness and cracks on the surface that may affect subsequent processing;

[0029] (2) The ingot is heated in a walking beam heating furnace at a temperature of 780 to 800°C for 5.5 to 7.5 hours and kept warm for 4.5 to 6.5 hours. The ingot is then taken out of the furnace after being evenly heated.

[0030] (3) Use a high-pressure spray gun to remove the surface oxide scale before hot rolling, control the hot rolling temperature at 350°C, use 9 passes for hot rolling, the total processing rate of the hot-rolled strip is ≥90%, and spray water on the hot rolling roller after the final hot rolling pass;

[0031] (4) Mill the surface and edge of the blank on a double-sided milling machine, with a milling cutter speed of 700-900 r / min and a milling speed of 8-20 m / min to ensure that there is no peeling, oxidation pits, adhesion chips, or cracked edges on the surface;

[0032] (5) After milling, the blank is sampled and tested to analyze the grain size. The final product grain size is 0.050 mm. After meeting the performance requirements, the finished product is packaged and put into storage.

[0033] Embodiment 2:

[0034] This embodiment uses H70 copper-zinc alloy ingots with specifications of 210mm×620mm×6m, and the technical requirements are as follows:

[0035] Brand-state: H70-R

[0036] Finished product specifications: 14.5mm×672mm

[0037] Performance requirements: grain size ≤ 0.085mm

[0038] The specific process steps are as follows:

[0039] (1) Raw material inspection: Perform an appearance inspection on the H70 copper-zinc alloy ingot, remove the bad gate defects, and ensure that there are no looseness, cracks, and other defects on the surface that affect subsequent processing;

[0040] (2) Homogenization annealing: In a nitrogen or CO2 atmosphere containing trace oxygen, the ingot is heated in a walking beam heating furnace. The heating temperature is controlled at 790-810°C for 5.5-7.5 hours and the heat preservation time is 4.5-6.5 hours. The ingot is gradually transferred by the rising, forward, descending and backward movements of the water-cooled metal beam so that the ingot is evenly heated and then taken out of the furnace.

[0041] (3) Hot rolling: Use a high-pressure spray gun to remove the surface oxide scale before hot rolling. The hot rolling temperature is controlled at 370°C. Nine passes are used for rolling. The total processing rate of the hot-rolled strip is ≥90%. After the final hot rolling pass, water spray cooling is performed on the hot rolling roller.

[0042] (4) Surface treatment: Mill the surface and edges of the blank on a double-sided milling machine, with a milling cutter speed of 700-900 r / min and a milling speed of 8-20 m / min to ensure that there is no peeling, oxidation pits, adhesion chips, or cracked edges on the surface;

[0043] (5) Quality inspection: The blank after milling was sampled and inspected. The grain size of the final product was 0.065 mm, which met the performance requirements.

[0044] Embodiment 3:

[0045] This embodiment uses H70 copper-zinc alloy ingots with specifications of 230mm×620mm×6m, and the technical requirements are as follows:

[0046] Brand-state: H70-R

[0047] Finished product specifications: 14.5mm×672mm

[0048] Performance requirements: grain size ≤ 0.08mm

[0049] The specific process steps are as follows:

[0050] (1) Raw material inspection: Perform an appearance inspection on the H70 copper-zinc alloy ingot, remove the bad gate defects, and ensure that there are no looseness, cracks, and other defects on the surface that affect subsequent processing;

[0051] (2) Homogenization annealing: In a nitrogen or CO2 atmosphere containing trace oxygen, the ingot is heated in a walking beam heating furnace. The heating temperature is controlled at 800-820°C for 6.5-8.5 hours and the heat preservation time is 5-7 hours. The ingot is gradually transferred by the rising, forward, descending and backward movements of the water-cooled metal beam so that the ingot is evenly heated and then taken out of the furnace.

[0052] (3) Hot rolling: Use a high-pressure spray gun to remove the surface oxide scale before hot rolling. The hot rolling temperature is controlled at 390°C. Ten passes are used for rolling. The total processing rate of the hot-rolled strip is ≥90%. After the final hot rolling pass, water spray cooling is performed on the hot rolling roller.

[0053] (4) Surface treatment: Mill the surface and edges of the blank on a double-sided milling machine, with a milling cutter speed of 700-900 r / min and a milling speed of 8-20 m / min to ensure that there is no peeling, oxidation pits, adhesion chips, or cracked edges on the surface;

[0054] (5) Quality inspection: The blank after milling was sampled and inspected. The grain size of the final product was 0.070 mm, which met the performance requirements.

[0055] It can be seen from the above three embodiments that the process method of the present invention has good applicability to copper-zinc alloys of different specifications and compositions. By reasonably controlling the process parameters, the grain structure can be effectively refined. The grain size of the final product is better than 0.08 mm, and the surface quality is good, meeting the requirements of industrial production.

Claims

1. A process for refining the grain size of a copper-zinc alloy hot-working structure, characterized in that: The following steps are involved: Carry out appearance inspection on copper-zinc alloy ingots, remove bad gate defects, and ensure that there are no loose or crack defects on the surface; In a nitrogen or CO2 atmosphere containing trace oxygen, a step-beam heat treatment furnace is used to homogenize the ingot, the heating temperature is controlled at 750-850°C, the heating time is 4-10 hours, and the holding time is 3-8 hours; After the ingot is annealed and taken out of the furnace, the surface oxide scale is removed by a high-pressure spray gun, and hot rolling is carried out. The hot rolling temperature is controlled at 300-450℃, and the total processing rate of the hot-rolled strip is ≥90%; The hot-rolled billet was sampled and tested for grain size analysis.

2. The process for refining the grain size of the hot-working structure of copper-zinc alloy according to claim 1 is characterized in that: The walking beam heat treatment furnace gradually transfers the ingots through the rising, advancing, descending and retreating actions of the water-cooled metal beam, and adopts a side-in and side-out loading and unloading method.

3. The process for refining the grain size of the hot-working structure of copper-zinc alloy according to claim 1, characterized in that: The hot rolling is performed in 9 passes.

4. The process for refining the grain size of the hot-working structure of copper-zinc alloy according to claim 1 is characterized in that: The thickness of the copper-zinc alloy ingot is 210 mm-260 mm.

5. The process for refining the grain size of the hot-working structure of copper-zinc alloy according to claim 1, characterized in that: After hot rolling, water spray cooling is carried out on the hot rolling roller.

6. The process for refining the grain size of the hot-working structure of copper-zinc alloy according to claim 1, characterized in that: The hot-rolled products are milled on the double-sided milling machine with the milling cutter speed of 700-900r / min and the milling speed of 8-20m / min.

7. The process for refining the grain size of a hot-working copper-zinc alloy according to any one of claims 1 to 6, characterized in that: The copper-zinc alloy is H70 alloy, the heating temperature is 790-810°C, the heating time is 5.5-7.5 hours, the insulation time is 4.5-6.5 hours, and the hot rolling temperature is 370°C.

8. The process for refining the grain size of a copper-zinc alloy hot-working structure according to any one of claims 1 to 6, characterized in that: The copper-zinc alloy is H65 alloy, the heating temperature is 780-800°C, the heating time is 5.5-7.5 hours, the insulation time is 4.5-6.5 hours, and the hot rolling temperature is 350°C.