A method and process for stress relief of large welded structural parts

Technical characteristics:

1. There is a method for stress relief of a large welded structural member, wherein the large welded structural member contains a first plate and a second plate which are welded and fixed, and a third plate which is either welded and fixed to the first plate or to the second plate, and the thicknesses of the first and second plates are all greater than that of the third plate. Firstly, the first weld between the first plate and the second plate is annealed locally; then the second weld between the first plate or the second plate and the third plate is dehydrogenated after welding; finally, the large welded structural parts are carried out as a whole.vibration aging2. For the method of stress relief for large welded structural parts as claimed in claim 1, it has the feature that the first weld between the first plate (11) and the second plate (12) is subjected to a local annealing treatment, which consists of the following steps, firstly, the first plate (11) and the second plate (12) are heated in a furnace, so that the temperature of the furnace rises to the heat treatment temperature, and then the furnace is cooled at a temperature of more than 300°C, until the temperature is higher than 300°C, and then the furnace is cooled at a temperature of more than 300°C, until the temperature of the furnace rises to a temperature of more than 300°C. Heat treatment temperature, then it is, according to the first plate (11) and the second plate (12) of the plate thickness to keep warm, and then and is, in the furnace temperature temperature is greater than 300 ℃ under the condition of cooling, until the furnace temperature is lowered to 300 ℃ or less, and then the first plate (11) and the second plate (12) from the furnace to remove the cooler. 3. a large welded structural components of the elimination of stress, as claimed in claim 2. Claim 2, characterised in that the heating rate between the first plate member (11) and the second plate member (12) is greater than or equal to 50°C/h and at the same time less than or equal to 55°C/h. A further feature of the method for stress relief of large welded structural members like the one referred to in claim 2 is that, during the period of time when the heating is carried out, the temperature difference between any part of the furnace where the first plate member (11) or the second plate member (12) is located is less than or equal to 50°C/h at the same time. Within a predetermined distance, the temperature difference is less than or equal to 120°C. 5. The method for stress relief of large welded structural members as claimed in claim 2, characterised in that when said first plate member (11) and said second plate member (12) are cooled in the furnace, the cooling rate is less than or equal to 65°C/h. 6. The method for stress relief of structural members, characterised in that the post-welding dehydrogenation treatment of the second weld seam between the first plate member (11) or the second plate member (12) and the third plate member (13) comprises: heating the second weld seam between the first plate member (11) or the second plate member (12) and the third plate member (13) to a temperature of 200°C to 300°C, and holding it thereafter, and then slowly cooling it to room temperature after the holding time has been reached. , slowly cooled to room temperature.7. The method for stress relief of large welded structural members as claimed in claim 6, characterised in that the holding time of said second weld is selected from the maximum plate thickness of the joint part of the weldment and is determined according to the holding time of greater than or equal to 0.5h for every 25mm of plate thickness, while the total holding time is greater than or equal to 1h. 8. The method of stress elimination of large welded structural members as claimed in claim 6, which is characterised by the use of heat preservation cotton to cover the second weld to keep warm. 9. The method of stress elimination of large welded structural members as claimed in claim 1, which is specialised in the vibration aging treatment for large welded structural members as a whole, which includes placing the elastic support at the bottom of the large welded structural members so that the large welded structural members can be placed smoothly, and then the large welded structural members are treated with vibration aging treatment. The large welded structural member is then subjected to a cyclic excitation force similar to its intrinsic resonance frequency for sub-resonance. 10. A method for removing stress from a large welded structural member as claimed in claim 1, characterised in that:

After vibration ageing of the entire large welded structural member (1), the residual stresses in the first and second welds were tested by the magnetic strain method.