Continuous friction weak standard welding method for large ultrahigh-strength steel workpiece

Abstract

The invention discloses a continuous friction weak standard welding method for a large ultrahigh-strength steel workpiece, which comprises the following steps of: processing an annealed D50Re blank into a welding sub-part, and clamping the welding sub-part on a friction welding machine; according to the equivalent diameter friction linear speed of 1.0-2.5 m / s, the sub-parts are machined into part blanks through three-stage pressurization friction welding; and the part blank is machined to remove flashes, and the D50Re ultra-high-strength steel complex part is obtained. According to the method, large D50Re ultrahigh-strength steel complex parts of different specifications can be produced, the material utilization rate and the production efficiency are greatly improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of friction welding, and in particular relates to a continuous friction weak-regulation welding method for a large ultra-high-strength steel workpiece. Background Art

[0002] D50Re steel is a new type of ultra-high strength steel developed for rocket deep blind hole shells. It is based on medium alloy steel containing Cr, Ni, Mo, and Si, and adds W, V, Nb and other elements to improve strength through solid solution strengthening and precipitation strengthening. Through the reasonable configuration of Cr, Ni, Mo, Si, W, and V, high toughness is obtained, and the tensile strength Rm ≥ 1600Mpa. Due to the limitations of existing manufacturing processes, large ultra-high strength steel components with complex shapes, such as stepped shafts (cross-sectional area 100000mm 2 , length 2000 ~ 3000mm), using forged solid bar, overall machining manufacturing process, there are problems such as low material utilization, long production cycle, high cost.

[0003] As a high-quality, precise, efficient and energy-saving solid-state welding technology, friction welding has been applied to high-tech fields such as aviation, aerospace, nuclear industry, and marine development, and has become the most reliable and trustworthy welding method for important components such as aircraft engine rotors. Friction welding provides technical potential and application prospects for the welding and manufacturing of deep blind hole shells of rockets to replace integral forging processing.

[0004] The friction welding process parameter range is generally divided into two types: strong specification and weak specification: strong specification refers to high friction pressure, low speed, short friction time; weak specification refers to low friction pressure, high speed, long friction time. Strong specification welding has high production efficiency, short high temperature residence time in the welding zone and its nearby area, fine structure, good joint strength and toughness, but for cross-sectional area of ​​100000mm 2 Large workpieces require giant friction welding equipment, which is a fatal obstacle to the development of friction welding of large workpieces. Weak specifications are suitable for welding larger cross-sections when the equipment capacity is certain, but friction welding of ultra-high strength steel with weak specifications is not sufficient, and there is no relevant description in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a continuous friction weak standard welding method for large ultra-high strength steel workpieces, which can produce solid cross-sectional areas of 5000-100000mm according to the needs of friction welding of large-section solid D50Re ultra-high strength steel complex workpieces. 2 Large and complex D50Re ultra-high strength steel parts of different specifications can greatly improve material utilization and production efficiency and reduce production costs.

[0006] To achieve the above purpose, the technical solution used in the present invention is:

[0007] Continuous friction weak standard welding method for large ultra-high strength steel workpieces, including:

[0008] Processing the annealed D50Re blank into a welding sub-part, and clamping the welding sub-part on a friction welding machine;

[0009] According to the equivalent diameter friction line speed of 1.0 to 2.5 m / s, the sub-parts are processed into part blanks by three-stage pressure friction welding;

[0010] The blank parts are machined to remove the flash and obtain D50Re ultra-high strength steel complex parts.

[0011] Furthermore, the three-stage pressure friction welding process includes: a first-stage pressure friction preheating, a second-stage pressure friction heating, and a third-stage pressure upsetting welding.

[0012] Furthermore, the first-level friction pressure is 10-20Mpa, the friction time is 25-35s, and the peak torque is controlled; the second-level friction pressure is 25-45Mpa, and the friction is continued until the outer surface temperature of the friction interface is ≥1180°C; the third-level friction pressure is 110-150Mpa, and the upsetting and holding time is ≥60s.

[0013] Furthermore, during the three-stage pressure upsetting welding process, the upsetting shortening amount is ≥10 mm.

[0014] Furthermore, the amount of shortening by upsetting is 18 to 41 mm.

[0015] Furthermore, the part blank is put into a furnace for annealing at a temperature of 650°C to 800°C. After being evenly heated and kept warm, it is taken out of the furnace and air-cooled to room temperature.

[0016] Furthermore, the annealing temperature is 780±10°C, the average temperature time is 1-2 hours, and the heat preservation time is 3-6 hours.

[0017] Furthermore, during the annealing process, the holding time is adjusted according to the wall thickness and is calculated as no less than 2 min / mm wall thickness.

[0018] Furthermore, the D50Re ultra-high strength steel complex parts were subjected to performance heat treatment.

[0019] The technical effects of the present invention include:

[0020] The present invention realizes the friction welding of large workpieces with weak specifications of ultra-high strength steel, which is of great significance to the development of large-section friction welding technology. In view of the demand for friction welding of large-section solid D50Re ultra-high strength steel complex workpieces, the present invention can produce solid cross-sectional areas of 5000-100000mm 2 Complex parts made of D50Re ultra-high-strength steel of different specifications can greatly improve material utilization and production efficiency and reduce production costs.

[0021] The present invention is based on a three-stage pressurized friction welding process, implements weak friction standard welding of D50Re ultra-high strength steel workpieces, reduces friction pressure and upset pressure, and reduces friction torque and equipment upset load, which is of great significance to the innovation of friction welding process of D50Re ultra-high strength steel workpieces and the development of welding equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the continuous friction weak specification welding method of large ultra-high strength steel workpieces in the present invention;

[0023] Figure 2 is a microstructure diagram of a complex part of D50Re ultra-high strength steel in Example 1 of the present invention;

[0024] Figure 3a is a grain size diagram of the welding area of ​​a complex part of D50Re ultra-high strength steel in Example 1 of the present invention;

[0025] Figure 3b is a grain size diagram of the heat-affected zone of a complex part of D50Re ultra-high strength steel in Example 1 of the present invention;

[0026] Figure 3c is a grain size diagram of the D50Re ultra-high strength steel complex part base material in Example 1 of the present invention;

[0027] Figure 4 is a microstructure diagram of a complex part of D50Re ultra-high strength steel in Example 2 of the present invention;

[0028] Figure 5a is a grain size diagram of the welding area of ​​a complex part of D50Re ultra-high strength steel in Example 2 of the present invention;

[0029] Figure 5b is a grain size diagram of the heat-affected zone of a complex part of D50Re ultra-high strength steel in Example 2 of the present invention;

[0030] Figure 5c This is a grain size diagram of the D50Re ultra-high strength steel complex part base material in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0032] Aiming at the demand for friction welding of large-section solid D50Re ultra-high-strength steel complex workpieces, the present invention adopts a three-stage pressurized friction welding process, namely, first-stage pressure friction preheating, second-stage pressure friction heating, and third-stage pressure upsetting welding. By greatly reducing the friction pressure, controlling the friction time, optimizing the upsetting pressure and other process measures, the D50Re ultra-high-strength steel workpiece is welded. The mechanical properties of the joint after heat treatment are yield strength Rm≥1660Mpa, plastic elongation strength Rp0.2 (the strength value corresponding to the plastic elongation of 0.2%)≥1330Mpa, elongation after fracture A≥8%, section shrinkage Z≥40%, and impact absorption energy KU2≥52J of the U-notch specimen under a 2mm hammer blade. Not only does it meet the standard requirements of D50Re ultra-high-strength steel forgings, but the measured mechanical properties are equivalent to those of the parent material.

[0033] like Figure 1 The figure shows a flow chart of the continuous friction weak-standard welding method for large ultra-high-strength steel workpieces in the present invention.

[0034] The continuous friction weak standard welding method of large ultra-high strength steel workpieces specifically includes the following steps:

[0035] Step 1: Process the annealed D50Re blank into a welding sub-part, and clamp the welding sub-part on a friction welding machine;

[0036] Step 2: According to the equivalent diameter friction line speed of 1.0 to 2.5 m / s, the sub-parts are processed into part blanks by three-stage pressurized friction welding;

[0037] Step 21: First-stage pressure friction preheating,

[0038] The first-level friction pressure is 10-20Mpa, the friction time is 25-35s, and the peak torque is controlled;

[0039] Step 22: Secondary pressure friction heating;

[0040] The secondary friction pressure is 25-45 MPa, and the friction is continued until the outer surface temperature of the friction interface is ≥1180℃;

[0041] Step 23: Three-stage pressure forging welding.

[0042] The third-level friction pressure is 110-150 MPa, and the upsetting and holding time is ≥60 s. In this preferred embodiment, the upsetting shortening amount is ≥10 mm, and the preferred upsetting shortening amount is 18-41 mm.

[0043] Step 3: Put the blank into the furnace for annealing at a temperature of 650°C to 800°C. After equalization and heat preservation, take it out of the furnace and air cool it to room temperature.

[0044] In order to enhance the material processing properties, the workpiece must be annealed after welding; in the preferred embodiment, the annealing temperature is 780±10°C, the equalization time is 1-2 hours, and the insulation time is 3-6 hours (calculated as no less than 2min / mm wall thickness). The insulation time is adjusted according to the wall thickness and is calculated as no less than 2min / mm wall thickness.

[0045] Step 4: The blank of the part annealed after welding is machined to remove the flash and subjected to performance heat treatment to obtain a D50Re ultra-high strength steel complex part.

[0046] In order to further enhance the strength of complex parts made of D50Re ultra-high strength steel, performance heat treatment is carried out after removing the flash.

[0047] Example 1

[0048] Welding sub-parts specifications: Φ100mm×105mm, welding area: 7850mm 2 .

[0049] 1. Use annealed forgings that meet the performance requirements and process them into welding sub-parts according to the drawings;

[0050] 2. Clamp the sub-parts on a 130-ton friction welding machine;

[0051] 3. According to the equivalent diameter friction line speed of 1.0m / s, the sub-parts are welded into part blanks according to the following process parameters:

[0052] ①, First-stage pressure friction preheating;

[0053] The first-level friction pressure is 15Mpa and the friction time is 30s.

[0054] ②, Secondary pressure friction heating;

[0055] Secondary friction pressure 30Mpa, friction time 210s, outer surface temperature of friction interface 1180℃;

[0056] ③. Three-level pressure forging welding.

[0057] The third-level friction pressure is 130Mpa, the upsetting and holding time is greater than 60s, and the upsetting shortening is ≥10mm.

[0058] 4. Put the welded parts into the furnace for annealing: annealing temperature 780±10℃, average temperature time 2 hours, heat preservation time 6 hours (calculated as no less than 2min / mm wall thickness), and air cool to room temperature after being taken out of the furnace;

[0059] 5. Machining the annealed parts to remove flash;

[0060] 6. Perform performance heat treatment on the blank parts with the flash removed to obtain D50Re ultra-high strength steel complex parts.

[0061] 7. Physical and chemical testing

[0062] 7.1 Mechanical properties (transverse)

[0063]

[0064] 7.2 Metallographic Structure

[0065] like Figure 2 , which is a microstructure diagram of a complex part made of D50Re ultra-high strength steel in Example 1 of the present invention.

[0066] The microstructures of the welding zone, heat affected zone and base material are all tempered troostite.

[0067] 7.3 Grain size

[0068] like Figure 3a As shown, it is a grain size diagram of the welding area of ​​the D50Re ultra-high strength steel complex parts in Example 1 of the present invention; Figure 3b As shown, it is a grain size diagram of the heat-affected zone of a complex part of D50Re ultra-high strength steel in Example 1 of the present invention; Figure 3c , which is a grain size diagram of the D50Re ultra-high strength steel complex part base material in Example 1 of the present invention.

[0069] The grain sizes of the welding zone, heat affected zone and base material are 7.0, 5.0 and 5.0 respectively.

[0070] Example 2

[0071] Welding sub-parts specifications: Φ100mm×105mm, welding area: 7850mm 2 .

[0072] 1. Use annealed forgings that meet the performance requirements and process them into welding sub-parts according to the drawings;

[0073] 2. Clamp the welding sub-parts on the 130-ton friction welding machine;

[0074] 3. According to the equivalent diameter friction line speed of 2.5m / s, the welding sub-parts are welded into part blanks according to the following process parameters;

[0075] ①, First-stage pressure friction preheating;

[0076] The first level pressure friction is 15Mpa and the friction time is 30s.

[0077] ②, Secondary pressure friction heating;

[0078] The secondary pressure is 30 MPa, the friction time is 210 s, and the outer surface temperature of the friction interface is ≥ 1180 °C.

[0079] ③. Three-level pressure forging welding.

[0080] The third-level pressure is 130Mpa, the upsetting and holding time is ≥60s, and the upsetting shortening is ≥10mm.

[0081] 4. Put the welded parts into the furnace for annealing: annealing temperature 780±10℃, average temperature time 2 hours, insulation time 6 hours (calculated based on no less than 2min / mm wall thickness), and air cool to room temperature after taking out of the furnace.

[0082] 5. Machining the blank parts after welding annealing to remove the flash;

[0083] 6. The welded parts with the flash removed are subjected to performance heat treatment to obtain D50Re ultra-high strength steel complex parts.

[0084] 7. Physical and chemical testing

[0085] 7.1 Mechanical properties (transverse)

[0086]

[0087] 7.2 Metallographic Structure

[0088] like Figure 4 , which is a microstructure diagram of a complex part made of D50Re ultra-high strength steel in Example 2 of the present invention.

[0089] The microstructures of the welding zone, heat affected zone and base material are all tempered martensite.

[0090] 7.3 Grain size

[0091] like Figure 5a As shown, it is a grain size diagram of the welding area of ​​the D50Re ultra-high strength steel complex parts in Example 2 of the present invention; Figure 5b As shown, it is a grain size diagram of the heat-affected zone of a complex part of D50Re ultra-high strength steel in Example 2 of the present invention; Figure 5c , which is a grain size diagram of the D50Re ultra-high strength steel complex part base material in Example 2 of the present invention.

[0092] The grain sizes of the welding zone, heat affected zone and base material are 7.0, 6.0 and 6.5 respectively.

[0093] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the attached claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the attached claims.

Claims

1. A method for continuous friction weak-regulation welding of large ultra-high strength steel workpieces, comprising: Processing the annealed D50Re blank into a welding sub-part, and clamping the welding sub-part on a friction welding machine; According to the equivalent diameter friction line speed of 1.0 to 2.5 m / s, the sub-parts are processed into part blanks by three-stage pressure friction welding; The three-stage pressure friction welding process includes: first-stage pressure friction preheating, second-stage pressure friction heating, and third-stage pressure upsetting welding. The first-stage friction pressure is 10-20Mpa, the friction time is 25-35s, and the peak torque is controlled; the second-stage friction pressure is 25-45Mpa, and the friction is continued until the outer surface temperature of the friction interface is ≥1180℃; the third-stage friction pressure is 110-150Mpa, the upsetting and holding time is ≥60s, and the upsetting shortening is ≥10mm; Put the blank into the furnace for annealing, the annealing temperature is 780±10℃, the average temperature time is 1-2 hours, the heat preservation time is 3-6 hours, and then it is air-cooled to room temperature after being taken out of the furnace; The blank parts annealed after welding are machined to remove the flash and subjected to performance heat treatment to obtain D50Re ultra-high strength steel complex parts.

2. The continuous friction weak standard welding method for large ultra-high strength steel workpieces according to claim 1, characterized in that: The shortening of top forging is 18 to 41 mm.

3. The continuous friction weak standard welding method for large ultra-high strength steel workpieces according to claim 1, characterized in that: During the annealing process, the holding time is adjusted according to the wall thickness and is calculated as no less than 2min / mm wall thickness.

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