K4002 nickel-based superalloy MPAW flat plate surfacing process based on reciprocating vibration wire feeding

Abstract

The invention discloses a K4002 nickel-based superalloy MPAW plate surfacing process based on reciprocating vibration wire feeding, and is suitable for the field of additive remanufacturing. According to the technology, aiming at the defects that a K4002 high-temperature alloy surfacing welding bead is small in width-height ratio, welding defects are prone to being generated, and a well-formed welding bead is difficult to obtain, on the premise that low cost and high applicability of PAW are guaranteed, vibration wire feeding is introduced, the reasonable welding speed and welding current are matched, the welding bead appearance is improved while the good droplet transition effect is obtained, and the welding quality is improved. The surfacing process of the hard-to-weld nickel-based superalloy flat plate is achieved, the continuity and uniformity of a welding bead are good, the width-to-height ratio of a welding seam is moderate, the transition of a weld toe is smooth, and no obvious welding defect exists. According to the process, the surfacing forming effect of the difficult-to-weld nickel-based superalloy can be remarkably improved. The method has important significance in promoting application and development of the MPAW technology in the field of additive repair of nickel-based high-temperature alloy aerospace components.

Description

Technical Field

[0001] The invention proposes a K4002 nickel-based high-temperature alloy MPAW flat plate surfacing process based on reciprocating vibration wire feeding, belongs to the technical field of additive manufacturing, and is suitable for the repair process of aircraft engine blades. Background Art

[0002] In aircraft engines, turbine rotor blades are exposed to high-temperature combustion gases, corrosion and various stresses for a long time, and are prone to fatigue thermal cracks, small-area surface damage fatigue fractures and other defects during service. In addition, the materials used to manufacture turbine blades are mostly cast nickel-based high-temperature alloys, which have a high degree of alloying and a very low precision casting rate. Most of the finished blades contain casting defects such as shrinkage and shrinkage. In order to meet the requirements of engine use, the cost of repairing blades is only 20% of that of replacing new blades, which is more in line with the increasingly fierce competition in the modern manufacturing industry. The requirements for reducing costs are getting higher and higher. Therefore, achieving efficient and high-quality engine blade repair has become an important link for major companies in the aerospace field.

[0003] At present, the mainstream repair method for aircraft engine blades is welding repair, which is divided into laser welding repair, arc welding repair, and electron beam welding repair. Laser welding repair has high precision, but its energy efficiency is low and the cost is high; electron beam welding repair is subject to the process requirement of high vacuum environment, and arc welding repair has high deposition efficiency, low cost, and high process freedom, but its heat input is large and the repair quality is poor.

[0004] In response to the above problems, micro-plasma welding technology has received extensive attention in the field of aircraft engine repair. Micro-plasma welding is an improved technology of arc welding. It forms a free arc by applying sufficient voltage between the tungsten electrode and the nozzle or workpiece to ionize the gas. Under the compression of the nozzle, cold air flow and magnetic field, a plasma arc with fully ionized gas and high energy density is formed for welding repair. It improves energy density and reduces heat input based on the advantages of arc welding. However, the micro-plasma process parameters are numerous and complex, and the influence of process parameters on welding forming is not yet clear. In the repair process of difficult-to-weld alloys such as K4002, humps and uneven welding defects are prone to occur, and the aspect ratio of the cladding layer is often small, making it difficult to repair actual components.

[0005] At present, the microbeam plasma repair process of difficult-to-weld alloys such as K4002 has not been well optimized, which to some extent restricts the development of MPAW in the field of aircraft engine blade repair. Summary of the invention

[0006] In view of the limitations of the background technology, the present invention proposes a K4002 nickel-based high-temperature alloy MPAW flat plate surfacing process based on reciprocating vibration wire feeding, which can solve the problem of poor weld formation of K4002 cast nickel-based high-temperature alloy repair without changing the welding process, and obtain effective, continuous and uniform weld formation, with the advantages of high reliability and good flexibility.

[0007] The technical solution of the present invention is:

[0008] A K4002 nickel-based high-temperature alloy MPAW flat plate surfacing process based on reciprocating vibration wire feeding, using a K4002 cast nickel-based high-temperature alloy with a thickness of 40 mm as the base plate, and using HGH3113 welding wire; using MPAW arc as the welding heat source, the welding current is 50A, the welding voltage is 16V, the welding speed is 0.12m / min, the welding wire diameter is 1.1mm, the nozzle diameter is 1.8mm, the welding wire is 3mm away from the nozzle, the shielding gas is pure argon, and the flow rate is 12L / min.

[0009] Furthermore, the reciprocating vibration wire feeding is realized by an IDA-tig Speed ​​oscillation drive 45 hotwire automatic wire feeding machine, and the wire feeding vibration frequency is set to 16 Hz, so that the welding wire vibrates to cause the molten droplets to fall, transferring kinetic energy to the molten pool.

[0010] Furthermore, the MPAW equipment used is IDA Microplasma105. digital welding machine, and the automatic welding machine is Dingdian HCD500-8.

[0011] Furthermore, the specific welding parameters in the welding process are directly set by the welding machine, and the specific welding gun posture and welding path are set by adjusting the automatic welding machine.

[0012] Furthermore, reciprocating vibration wire feeding is added while appropriately adjusting welding parameters to ensure the stability of welding heat input and weld metal filling amount.

[0013] Furthermore, after welding is completed, the weld macroscopic formation and cross-sectional metallographic morphology are sampled and photographed.

[0014] The beneficial effects of the present invention are as follows: first, the use of reciprocating vibration to feed the wire can give the welding wire an additional transitional power. The molten droplets formed after the welding wire is melted actively separate from the welding wire and enter the molten pool through reciprocating pumping oscillation. The kinetic energy of the pulsating oscillation of the welding wire is transmitted to the molten pool through the molten droplets, which produces a strong stirring effect on the molten pool, homogenizes the molten pool, improves the welding metallurgical effect, and allows pores, impurities, etc. to escape, which helps to form the weld well and improve the weld performance. Secondly, the use of traditional continuous wire feeding for nickel-based high-temperature alloys can easily lead to large droplets entering the molten pool, which in turn leads to weak welds and asymmetric weld surfaces. Vibration wire feeding can use the kinetic energy of the front and rear vibrations to make smaller droplets separate from the welding wire and enter the molten pool when the droplet size is small, thereby avoiding the formation of large droplets. Therefore, this process can effectively improve the stability of the weld forming process and the quality of the weld, and reduce welding defects for nickel-based high-temperature alloys containing more Cr and Mo and having high surface tension of the molten phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of cladding experiment

[0016] Figure 2 Example 1-1 Macroscopic morphology of weld surface

[0017] Figure 3 Macroscopic morphology of weld surface in Example 1-2

[0018] Figure 4 Example 1-1 Weld cross section

[0019] Figure 5 Example 1-1 Welding seam metallographic structure DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments.

[0021] Example 1

[0022] A 4mm thick K4002 nickel-based high-temperature alloy was used as the substrate. The sample was processed to 250mm×200mm×40mm by wire cutting. The substrate surface was polished and ultrasonically cleaned before welding. The surface of the parent material was wiped with acetone to remove surface oxides, oil stains and other impurities. During the welding process, the surfacing substrate was clamped and fixed by a steel plate through a fixture.

[0023] The welding is done by using a top HCD500-8 automatic welding machine, and the welding wire is HGH3113 welding wire with a diameter of 1.1 mm. The welding current is 50A, the welding voltage is 16V, the welding speed is 0.12m / min, the wire feeding speed is 0.4m / min, the vibration frequency is 16HZ, and the shielding gas is pure argon with a flow rate of 12L / min.

[0024] After welding, the weld surface formation is photographed, and the weld metallographic specimens are prepared through mechanical cutting, inlaying, grinding, polishing, corrosion and other processes, and the cross-sectional metallographic morphology is photographed.

[0025] Example 2

[0026] A 4mm thick K4002 nickel-based high-temperature alloy was used as the substrate. The sample was processed to 250mm×200mm×4mm by wire cutting. The substrate surface was polished and ultrasonically cleaned before welding. The surface of the parent material was wiped with acetone to remove surface oxides, oil stains and other impurities. During the welding process, the surfacing substrate was clamped and fixed by a steel plate through a fixture.

[0027] The welding is done by using a top HCD500-8 automatic welding machine, and the welding wire is HGH3113 welding wire with a diameter of 1.1mm. The welding current is 50A, the welding voltage is 16V, the welding speed is 0.12m / min, the wire feeding speed is 0.4m / min, and the traditional continuous wire feeding is used. The shielding gas is pure argon gas with a flow rate of 12L / min.

[0028] After welding, the weld surface formation is photographed, and the weld metallographic specimens are prepared through mechanical cutting, inlaying, grinding, polishing, corrosion and other processes, and the cross-sectional metallographic morphology is photographed.

[0029] The weld surface morphology obtained in Example 1-1 is as follows Figure 2 As shown, the cross-sectional metallographic morphology is Figure 3 As shown. When the wire feeding vibration frequency is 16HZ and the welding speed is 0.12m / min, the weld surface shows high continuity and uniformity, the adjacent weld toes are well fused and the transition is smooth, and there are no obvious welding defects such as welding deviation, welding leakage, and hump weld. From the cross-sectional morphology, the weld surface has a large molten width. The weld molten width is measured to be 3.41mm, the excess height is 0.91mm, and the aspect ratio is moderate. No obvious internal defects such as pores, cracks, and lack of fusion are observed. From the metallographic results, the vicinity of the fusion line in the surfacing zone has grown into interlaced columnar dendrites and cellular crystals, and more white blocky eutectic phases and strip carbides can be seen in the heat-affected zone, and no obvious cracks are observed.

[0030] The surface morphology of the welded joint obtained in Example 1-2 is as follows: Figure 2 As shown, compared with the weld morphology obtained in Example 1-1 using 16HZ vibrating wire feeding, the weld in Example 1-2 is uneven in width, has an uneven surface, has undercuts, and has poor weld bead formation.

[0031] The results of the examples show that the MPAW flat plate surfacing process and parameters of K4002 nickel-based high-temperature alloy based on reciprocating vibration wire feeding proposed in the present invention can effectively solve the welding defects such as hump welds and undercuts that occur in the surfacing process of difficult-to-weld high-temperature alloys, improve the cladding effect while obtaining good weld formation quality, and provide a process basis for multi-layer and multi-pass repair of actual components. The present invention promotes the development of micro-beam plasma additive repair technology and provides an important technical reference for the widespread application of MPAW welding technology in the field of high-temperature alloy additive remanufacturing, with potential economic and social benefits.

[0032] The above description is only a partial embodiment of the present invention and is not a limitation of the present invention in any form. Any person familiar with the professional field, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the claims of the present invention.

Claims

1. A K4002 nickel-based high-temperature alloy MPAW flat plate surfacing process based on reciprocating vibration wire feeding, characterized in that: HGH3113 welding wire was used as filler metal for single-layer single-pass surfacing of K4002 nickel-based high-temperature alloy flat plate; micro-beam plasma arc was used as the welding heat source, the welding wire diameter was 1.1 mm, the nozzle diameter was 1.8 mm, the tungsten electrode was retracted 2 mm, the welding wire was 3 mm away from the nozzle, the welding current was 50 A, the welding voltage was 16 V, the welding speed was 0.12 m / min, the shielding gas was pure argon, the flow rate was 12 L / min, the wire feeding angle was 0°, and the welding gun was perpendicular to the test plate.

2. The MPAW flat plate surfacing process for K4002 nickel-based high-temperature alloy based on reciprocating vibration wire feeding according to claim 1 is characterized in that: By introducing reciprocating vibration wire feeding, mechanical vibration is applied to the welding wire to promote the transition of small molten droplets and vibrate and stir the molten pool, changing the molten pool morphology and behavior, thereby improving the welding deposition efficiency. When the wire feeding speed is 0.4m / min and the vibration frequency is 16HZ, the weld has good deposition properties, a smooth surface, uniform width, and no obvious welding defects.

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