A method for processing large single weight zirconium alloy wire

Abstract

The present application introduces a method for processing large unit weight zirconium alloy wire, which relates to the field of wire drawing technology, and the steps are: S1: ingot pretreatment; S2: blank forging; S3: first fire rolling; S4: cutting to size; S5: second fire rolling; S6: coil heat treatment; S7: cold drawing; S8: roller die cold drawing + continuous annealing; S9: surface treatment. The present invention combines blank forging, rolling, roller die cold drawing + continuous annealing and surface treatment, strictly controls the blank forging process, hot rolling temperature, etc., so that the zirconium alloy microstructure is fully refined and uniform, which is conducive to the smooth implementation of the subsequent drawing process; in the subsequent roller die cold drawing process, the drawing pass, deformation, cold drawing rate, etc. are strictly controlled to avoid the occurrence of cracks, defects and even wire breakage, and at the same time break through the bottleneck that the traditional drawing process cannot achieve large unit weight drawing of zirconium alloy, greatly improving the production efficiency and yield rate.

Description

Technical Field

[0001] The invention relates to the technical field of wire drawing technology, and in particular to a processing method for a large single weight zirconium alloy wire. Background Art

[0002] Zirconium alloys are widely used in reactors as cladding materials, core structural materials, control rod wire tubes, pressure tubes, etc. due to their good corrosion resistance to high-temperature water and superheated steam, good mechanical properties and low thermal neutron absorption cross-section, accounting for more than 80% of zirconium alloy applications; the traditional manufacturing method of zirconium alloy wires is mainly to extrusion or forging blanks, and then hot drawing in a fixed die, supplemented by a vacuum annealing process route; the traditional process route has many problems. First, during solution die drawing, due to the use of hot drawing, atmospheric surface oxidation treatment must be carried out before hot drawing, and each drawing pass requires a loading and unloading operation until the end of drawing, which greatly affects the production efficiency and product surface quality; secondly, during the hot drawing process, the drawing rate needs to be controlled at a low level to avoid wire breakage, so the processing steps are long and the production efficiency is low; finally, the hot drawing process is only suitable for small unit weight and small batch production, and the yield rate is low. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a large unit weight zirconium alloy wire processing process method, through the combination of billet forging, billet rolling, roller die drawing, continuous annealing and surface treatment, to achieve the processing of large unit weight high-quality zirconium alloy wire, simple operation, high yield rate, stable and controllable process.

[0004] The technical solution adopted by the present invention is:

[0005] A method for processing a large single weight zirconium alloy wire, the specific steps are:

[0006] S1: Ingot pretreatment: air-cool the cast zirconium alloy ingot to 600-700°C, apply anti-oxidation coating on the surface, heat and dry in a furnace at a heating temperature of 1100-1200°C, and keep warm for 4-6 hours;

[0007] S2: billet forging; heating the qualified ingot to between 1100°C and 1200°C, performing one-time forging, wherein the number of forging and drawing in this time is no more than two times, drawing the ingot to a square billet with a cross-sectional size of 180-200mm, air cooling and surface grinding treatment are performed to obtain a billet after billeting;

[0008] S3: First hot rolling: the square billet obtained in S2 is heated to 950-1050℃, and is rolled once to obtain a round bar with a diameter of Φ90-110mm and a length of not less than 10m. The ovality of the round bar is required to be no more than ±5cm. After air cooling, the round bar is peeled and pickled, and manually ground;

[0009] S4: Cut to size: Cut the round bar after grinding into sections, with each section of the round bar being 4-6m long;

[0010] S5: second hot rolling: the round bar obtained in S4 is heated to 850-950℃, and is rolled once to obtain a coil with a diameter of Φ8-10mm. The ovality of the coil is required to be no more than ±0.5cm. After air cooling, the coil is coiled, and the coil diameter is controlled to be Φ0.8m-1.1m;

[0011] S6: heat treatment of the coil; the coil obtained in S5 is annealed at a heating temperature of 700-800°C, kept at this temperature for 60-90 minutes, and then air-cooled after being taken out of the furnace;

[0012] S7: cold drawing; unwinding and drawing the coil obtained in S6, coating the surface with lubricant, drawing at a speed of 1-5 m / min, and stripping the coil on a centerless lathe after drawing it to a diameter of Φ7.0-7.5 mm, with a stripping speed of 1-15 m / min and a stripping amount of 0.3-0.5 mm. After stripping, manual visual inspection is performed to obtain a wire with no surface defects;

[0013] S8: roller die cold drawing + continuous annealing: the wire obtained in S7 is repeatedly cold drawn and annealed on a roller die wire drawing machine to obtain a wire of target diameter;

[0014] S9: surface treatment; ultrasonically clean and polish the wire of the target diameter obtained in S8 to obtain a finished zirconium alloy wire with a size that meets the precision requirements.

[0015] Specifically, the zirconium alloy ingot in S1 is an ingot with a diameter of 550-650 mm and a unit weight of 4-6 tons, and has no surface defects or damage.

[0016] Specifically, the pull-out deformation of S2 is 45-60%, and the deformation rate is controlled at 15-40 mm / s.

[0017] Specifically, the rolling rate in S3 is controlled at 0.5-1.0 m / s.

[0018] Specifically, in the S5, the rolling rate is controlled at 0.6-1.5 m / s.

[0019] Specifically, in the above-mentioned S8, the cold drawing and annealing treatments are repeated, and according to the gradual thinning of the wire diameter, 3-5 cold drawing processes are performed between each annealing.

[0020] More specifically, the S8 cold drawing speed is 10-50 m / min, the deformation per drawing pass is less than 35%, and the wire surface needs to be coated with an emulsion as a drawing lubricant.

[0021] Specifically, the continuous annealing temperature of the annealing treatment in S8 is 700-900° C., and the holding time is 10-30 minutes.

[0022] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages:

[0023] The invention effectively combines the means of blank forging, rolling, roller die cold drawing + continuous annealing and surface treatment, strictly controls the blank forging process, hot rolling temperature, etc., so that the zirconium alloy microstructure is fully refined and uniform, which is conducive to the smooth implementation of the subsequent drawing process; in the subsequent direct roller die cold drawing process, the roller die cold drawing pass deformation, cold drawing rate, etc. are strictly controlled to avoid the occurrence of cracks, defects and even wire breakage that may be generated in the drawing process, and at the same time, the bottleneck that the traditional drawing process cannot achieve large single weight drawing of zirconium alloy due to hot drawing is solved, and the production efficiency and yield rate are greatly improved; in the drawing process, the continuous annealing process in the cold drawing process is reasonably arranged, and the residual stress that may be generated by the zirconium alloy wire in the drawing process due to the uneven local deformation is effectively removed, and the static recrystallization annealing is realized, and the grain structure is further refined. At the same time, because the entire annealing process is completely carried out in an argon-filled environment, the subsequent use of electrolytic polishing or pickling to remove graphite or phosphorylated lubricant on the wire surface is effectively avoided, thereby achieving energy saving and environmental protection. DETAILED DESCRIPTION

[0024] The present invention will be further explained below in conjunction with the embodiments, which are not intended to limit the protection scope of the present invention. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0025] Example 1

[0026] The specific steps of preparing a Zr-4 zirconium alloy wire with a diameter of 1.0 mm and a single weight of 200 kg by the method of the present invention are as follows:

[0027] S1: Ingot pretreatment: The cast 6-ton Zr-4 zirconium alloy ingot is air-cooled to 700°C, the surface is coated with anti-oxidation paint, and the ingot is heated and dried in a furnace at a heating temperature of 1200°C for 6 hours.

[0028] S2: billet forging; the qualified ingot is heated to 1100℃ and forged once. The number of forging and drawing in this fire is two, the deformation of the drawing and drawing is 45%, and the deformation rate is 35mm / s. After air cooling, the surface is ground to obtain a square billet with a cross-sectional size of 190×190mm.

[0029] S3: first hot rolling; the square billet obtained in S2 is heated to 1000°C and rolled once. The rolling rate is controlled at 0.50 m / s to obtain 12 round bars with a diameter of Φ105 mm and a length of 10 m. The ovality of the round bars is 3 cm. After air cooling, the round bars are peeled and manually ground.

[0030] S4: Cut to size: the round bar after processing and grinding is cut into pieces, and the length of each round bar is 5m.

[0031] S5: Second hot rolling: The slit round bar is heated to 950°C and rolled once at a rolling rate of 0.8 m / s to obtain a coil with a diameter of Φ9 mm and an ovality of 0.2 cm. After air cooling, the coil is coiled and the coil diameter is Φ0.95 m.

[0032] S6: heat treatment of the coil; the coil after S5 is annealed at 800°C for 80 minutes and then air-cooled after being taken out of the furnace.

[0033] S7: cold drawing; the coil obtained in S6 is unwound and drawn, and a lubricant is coated on the surface. The drawing speed is 5 m / min, and the coil is drawn to a diameter of 7.2 mm and then peeled on a centerless lathe. The peeling speed is 15 m / min, and the peeling amount is 0.4 mm. After peeling, manual visual inspection is performed to obtain a wire with a surface defect-free diameter of 6.8 mm.

[0034] S8: roller die cold drawing + continuous annealing; the wire obtained in S7 is repeatedly cold drawn and annealed on a roller die wire drawing machine. The diameters of the wires after each roller die cold drawing are Ф6.1mm, Ф5.4mm, Ф4.8mm, Ф4.2mm, Ф3.7mm, Ф3.2mm, Ф2.7mm, Ф2.3mm, Ф1.9mm, Ф1.6mm, Ф1.4mm, Ф1.2mm and Ф1.0mm, respectively. After annealing, the wire diameters are set to Ф4.2mm, Ф2.3mm, Ф1.4mm and Ф1.0mm, respectively. The drawing speed is controlled at 10m / min, the annealing temperature is 820℃, the holding time is 15min, and a wire with a diameter of Ф1.0mm is obtained.

[0035] S9: surface treatment; the wire obtained in S8 is ultrasonically cleaned and polished, and finally a 200kg single-weight Ф1.0mm Zr-4 zirconium alloy wire with no weld point and a diameter tolerance of -0.01-0.02mm, a straightness of 3‰, and an overall yield rate of 65% from ingot to wire is obtained.

[0036] Example 2

[0037] The specific steps of preparing a Zr-4 zirconium alloy wire with a diameter of 1.2 mm and a single weight of 250 kg by the method of the present invention are as follows:

[0038] S1: Ingot pretreatment: The cast 6-ton Zr-4 ingot is air-cooled to 600°C, the surface is coated with anti-oxidation paint, and the ingot is heated and dried in a furnace at a heating temperature of 1100°C for 5 hours.

[0039] S2: billet forging; the qualified ingot is heated to 1200℃ and forged once. The number of forging and drawing in this fire is two, the deformation of the drawing and drawing is 60%, and the deformation rate is 40mm / s. After air cooling, the surface is ground to obtain a square billet with a cross-sectional size of 185×185mm.

[0040] S3: first hot rolling; the square billet obtained in S2 is heated to 950°C and rolled once. The rolling rate is controlled at 1.0 m / s to obtain 12 round bars with a diameter of Φ110 mm and a length of 10 m. The ovality of the round bars is 5 cm. After air cooling, the round bars are peeled and manually ground.

[0041] S4: Cut to size: Cut the round bar after grinding into sections, each section of the round bar is 5m long.

[0042] S5: second hot rolling; the slit round bar is heated to 880°C and rolled once at a rolling rate of 1.5 m / s to obtain a coil with a diameter of Φ8.5 mm and an ovality of 0.3 cm. After air cooling, the coil is coiled and the coil diameter is Φ1.1 m.

[0043] S6: heat treatment of the coil; the coil obtained in S5 is annealed at a heating temperature of 750°C for 90 minutes and then air-cooled after being taken out of the furnace.

[0044] S7: Cold drawing: The coil obtained in S6 is unwound and drawn, and lubricant is coated on the surface. The average drawing speed is 3.0 m / min. After drawing from the coil to a diameter of Φ7.3 mm, it is peeled on a centerless lathe. The peeling speed is 1 m / min, and the peeling amount is 0.5 mm. After peeling, manual visual inspection is performed to obtain a wire with a surface defect-free diameter of Φ6.8 mm.

[0045] S8: roller die cold drawing + continuous annealing: the wire obtained in S7 was repeatedly cold drawn and annealed on a roller die wire drawing machine. The diameters of the wires after each roller die cold drawing were Ф5.9mm, Ф5.2mm, Ф4.6mm, Ф3.8mm, Ф3.2mm, Ф2.6mm, Ф2.1mm, Ф1.8mm, Ф1.5mm, Ф1.3mm and Ф1.2mm, respectively. After annealing, the wire diameters were set to Ф3.8mm, Ф1.8mm and Ф1.0mm, respectively. The drawing speed was controlled at 50m / min, the annealing temperature was 900℃, the holding time was 20min, and a Ф1.2mm wire was obtained.

[0046] S9: surface treatment: the wire obtained in S8 is ultrasonically cleaned and polished, and finally a 250kg single-weight Ø1.2mm Zr-4 zirconium alloy wire with no weld point and a diameter tolerance of -0.01-0.01mm, a straightness of 2.8‰, and an overall yield rate of 66% from ingot to wire is obtained.

[0047] Example 3

[0048] The specific steps of preparing a Zr-2 zirconium alloy wire with a diameter of 1.2 mm and a single weight of 230 kg by the method of the present invention are as follows:

[0049] S1: Ingot pretreatment: The cast 6-ton Zr-2 ingot is air-cooled to 660°C, the surface is coated with anti-oxidation paint, and the ingot is heated and dried in a furnace at a heating temperature of 1160°C for 5 hours.

[0050] S2: billet forging; the qualified ingot is heated to 1150℃ and forged once. The number of forging and drawing in this fire is two, the deformation of the drawing and drawing is 50%, and the deformation rate is 15mm / s. After air cooling, the surface is ground to obtain a square billet with a cross-sectional size of 180×200mm.

[0051] S3: First hot rolling: The square billet obtained in S2 is heated to 1050°C and rolled once. The rolling rate is controlled at 0.8 m / s to obtain 12 round bars with a diameter of Φ95 mm and a length of 11 m. The ovality of the round bars is 3 cm. After air cooling, the round bars are peeled and manually ground.

[0052] S4: Cut to size: Cut the round bar after grinding into sections, with each section of the round bar being 5.5m long.

[0053] S5: second hot rolling; the round bar obtained in S4 is heated to 850°C and rolled once at a rolling rate of 1.1 m / s to obtain a coil with a diameter of Φ9.0 mm and an ovality of 0.3 cm. After air cooling, the coil is coiled and the coil diameter is Φ0.8 m.

[0054] S6: heat treatment of the coil; the coil obtained in S5 is annealed at a heating temperature of 700°C for 75 minutes and then air-cooled after being taken out of the furnace.

[0055] S7: cold drawing; the coil obtained in S6 is unwound and drawn, and a lubricant is coated on the surface. The drawing speed is 1.0 m / min. After drawing from the coil to a diameter of Φ7.1 mm, it is peeled on a centerless lathe. The peeling speed is 12 m / min, and the peeling amount is 0.3 mm. After peeling, manual visual inspection is performed to obtain a wire with a surface defect-free diameter of Φ6.8 mm.

[0056] S8: roller die cold drawing + continuous annealing; the wire obtained in S7 is repeatedly cold drawn and annealed on a roller die wire drawing machine. The wire diameters after each roller die cold drawing are Ф6.0mm, Ф5.1mm, Ф4.4mm, Ф3.7mm, Ф3.2mm, Ф2.6mm, Ф2.2mm, Ф1.8mm, Ф1.5mm, Ф1.3mm and Ф1.2mm, respectively. After annealing, the wire diameters are set to Ф4.4mm, Ф1.8mm and Ф1.2mm, respectively. The drawing speed is controlled at 40m / min, the annealing temperature is 700℃, and the holding time is 30min to obtain a Ф1.2mm titanium alloy wire.

[0057] S9: surface treatment; the wire obtained in S8 is ultrasonically cleaned and polished to finally obtain a 230kg single-weight Ø1.2mm Zr-2 zirconium alloy wire with a diameter tolerance of -0.01mm-0.02mm, a straightness of 3‰, and an overall yield rate of 65% from ingot to wire.

[0058] In summary, a comparison table of product data of zirconium alloy wires processed by the three embodiments of the present invention and the hot drawing process of the prior art is as follows. It can be seen that the process method adopted by the present invention significantly reduces the processing time, greatly increases the unit weight of the product, and the yield rate of the wire is significantly improved.

[0059] Parts of the present invention not described in detail are prior art.

[0060] The embodiments selected herein for the purpose of disclosing the invention are currently considered to be suitable, but it should be understood that the invention is intended to include all changes and modifications of the embodiments that fall within the scope of the concept and invention.

Claims

1. A method for processing a large single weight zirconium alloy wire, characterized in that: The specific steps are: S1: Ingot pretreatment: air-cool the cast zirconium alloy ingot to 600-700°C, the ingot is Ø550-650mm, the unit weight is 4-6 tons, and the surface has no defects or damage; apply anti-oxidation coating on the surface, heat and dry in the furnace, the heating temperature is 1100-1200°C, and keep warm for 4-6 hours; S2: forging; heating the qualified ingot to between 1100°C and 1200°C, performing one-time forging, wherein the number of forging and drawing in this time is no more than two times, drawing the ingot to a square billet with a cross-sectional side length of 180-200mm, air cooling and surface grinding treatment are performed to obtain a square billet after forging; S3: First hot rolling: the square billet obtained in S2 is heated to 950-1050℃, and is rolled once to obtain a round bar with a diameter of Φ90-110mm and a length of not less than 10m. The ovality of the round bar is required to be no more than ±5cm. After air cooling, the round bar is peeled and pickled, and manually ground; S4: Cut to size: Cut the round bar after grinding into sections, with each section of the round bar being 4-6m long; S5: second hot rolling: the round bar obtained in S4 is heated to 850-950℃, and is rolled once to obtain a coil with a diameter of Φ8-10mm. The ovality of the coil is required to be no more than ±0.5cm. After air cooling, the coil is coiled, and the coil diameter is controlled to be Φ0.8m-1.1m; S6: heat treatment of the coil; the coil obtained in S5 is annealed at a heating temperature of 700-800°C, kept at this temperature for 60-90 minutes, and then air-cooled after being taken out of the furnace; S7: cold drawing; unwinding and drawing the coil obtained in S6, coating the surface with lubricant, drawing at a speed of 1-5 m / min, and stripping the coil on a centerless lathe after drawing it to a diameter of Φ7.0-7.5 mm, with a stripping speed of 1-15 m / min and a stripping amount of 0.3-0.5 mm. After stripping, manual visual inspection is performed to obtain a wire with no surface defects; S8: roller die cold drawing + continuous annealing; the wire obtained in S7 is repeatedly cold drawn and annealed on a roller die wire drawing machine, and according to the gradual thinning of the wire diameter, 3-5 cold drawing times are performed between each annealing to obtain a wire of target diameter; S9: surface treatment; ultrasonically clean and polish the wire of the target diameter obtained in S8 to obtain a finished zirconium alloy wire with a size that meets the precision requirements.

2. The method for processing a large single weight zirconium alloy wire according to claim 1, characterized in that: The pull-out deformation of S2 is 45-60%, and the deformation rate is controlled at 15-40 mm / s.

3. The method for processing large single weight zirconium alloy wire according to claim 1, characterized in that: In the S3, the rolling rate is controlled at 0.5-1.0 m / s.

4. The method for processing a large single weight zirconium alloy wire according to claim 1, characterized in that: In the S5, the rolling rate is controlled at 0.6-1.5 m / s.

5. The method for processing a large single weight zirconium alloy wire according to claim 1, characterized in that: The S8 intermediate cold drawing speed is 10-50 m / min, the deformation per drawing pass is less than 35%, and the wire surface needs to be coated with an emulsion as a drawing lubricant.

6. The method for processing a large single weight zirconium alloy wire according to claim 1, characterized in that: The continuous annealing temperature of the annealing treatment in S8 is 700-900° C., and the holding time is 10-30 minutes.

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