A vacuum preheating electron beam welding method for large thickness workpieces

Abstract

The invention relates to a vacuum preheating electron beam welding method for large-thickness workpieces. The heating device is moved by a moving platform, and the workpiece to be welded is placed inside the heating device. The clamping tool and the heating device form a closed box structure, which is realized in a vacuum environment. High temperature preheating can effectively reduce the cooling rate, avoid the generation of hardened structures in the weld and heat affected zone, and obtain welded joints with better comprehensive performance; effectively prevent oxidation when the preheating temperature is high, and can meet the requirements of conventional workpieces and test plates. Vacuum preheating electron beam welding is used in the process development stage, and the preheating temperature is uniform and controllable at 50-1000℃.

Description

technical field [0001] The invention belongs to the field of metal material welding, in particular to a vacuum preheating electron beam welding method for workpieces with large thickness. Background technique [0002] With the development of material science, the application demand of new high-strength titanium alloys and high-strength steels is increasing. However, due to the increase in material strength, high-strength alloys have higher cold crack susceptibility during welding, and rapid cooling after welding will cause a large number of internal martensitic However, when the preheating temperature is high, the difficulty of manual welding is significantly increased, especially when the preheating temperature is high. When the thermal temperature is higher than 300 °C, the surface of the high-strength titanium alloy will react with hydrogen and oxygen in the air, and when the temperature is higher than 500 °C, it will react with nitrogen, which cannot be implemented in th...

AI Technical Summary

Problems solved by technology

[0002] With the development of material science, the demand for new high-strength titanium alloys and high-strength steels is increasing. However, due to the increase in material strength, high-strength alloys have higher sensitivity to cold cracks during welding. At the same time, rapid cooling after welding will cause a large number of internal martensites However, when the preheating temperature is high, the difficulty of manual welding increases significantly, especially when the preheating temperature is high. When the heating temperature is higher than 300°C, the surface of the high-strength titanium alloy will react with hydrogen and oxygen in the air, and when the temperature is higher than 500°C, it will react with nitrogen, which cannot be carried out in the atmosphere

[0003] Vacuum electron beam welding is performed under vacuum conditions, which can effectively avoid oxidation problems. However, due to the limitation of the vacuum heating environment, the inside of the electron beam welding machine is usually not able to be heated. The existing technology can only pre-weld pre-weld by defocusing preheating. However, electron beam defocusing preheating is only effective for thin plates (≤10mm), and the preheating temperature is difficult to control. There are significant temperature gradients and poor temperature uniformity. In actual engineering applications, the thickness of the workpiece will reach more than 100mm. Defocus preheating can no longer meet the demand. Therefore, there is an urgent need for a preheating welding process under vacuum conditions for high-strength alloy and large-thickness workpieces.

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