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If the stress of riveted weldments is not eliminated, the consequences will be serious.
In the processing of Q345 steel plate rivet weldments, welding residual stress is a common problem. In 2024, a machinery factory in Shandong failed to carry out stress relief work on a batch of Q345 steel plate rivet weldments with a thickness of 20mm. As a result, the welds cracked after delivery, causing direct losses of more than 500,000 yuan. During welding, due to high temperature heating and uneven cooling, tensile stress will occur inside the component. In severe cases, it will cause deformation or even fracture, which will directly affect the service life and safety of the equipment.
Post-weld heat treatment is the most reliable method of elimination
The riveted weldments are made of Q345 steel plates, and post-weld stress relief annealing is the most mainstream method in the industry. The specific operation is as follows. The entire weldment must be heated to 550°C to 650°C. The heat preservation time is calculated based on 2 to 3 minutes per millimeter of thickness. For example, a 30mm thick plate needs to be kept warm for 60 to 90 minutes, and then cooled slowly. This method can effectively release internal stress, and is especially suitable for riveted weldments that are thick or have complex structures.
Vibration aging is suitable for on-site treatment of large components
For Q345 steel plate rivet weldments that are large and cannot enter the furnace, vibration aging treatment is a good choice. In 2025, a steel structure company in Jiangsu adopted a vibration aging treatment method for a batch of bridge rivet weldments with a length of 12 meters. This method uses an exciter to apply the resonant frequency. The processing time is about 40 minutes, and the stress relief rate can reach 30% to 50%. Compared with the heat treatment method, its equipment is relatively simple and its energy consumption is relatively low, but the parameters need to be adjusted according to the size of the component.
Natural aging is simple but the cycle is too long
Q345 steel plate rivet weldments are placed in the open air or in a warehouse. This is called natural aging. It uses the temperature difference between day and night and seasonal changes to slowly release the stress. It is like a shipyard in Liaoning that once placed a batch of rivet weldments with a thickness of 16mm. It took up to 6 months for the effect of stress relief to become apparent. However, this method takes a long time and is not suitable for projects with tight construction periods. Moreover, the effect of stress relief is not very stable and stable, so it is rarely used in modern industrial production.
The selection method depends on the component thickness and working conditions.
It is necessary to eliminate stress for Q345 steel plate rivet weldments, and the selection method depends on the actual situation. For thin plate weldments with a thickness less than 12mm, vibration aging or natural aging can meet the requirements; for structures with a thickness of more than 20mm or that need to bear dynamic loads, such as lifting machinery bases, post-weld heat treatment must be used; data from a heavy industry company in Henan in 2025 shows that the fatigue life of riveted weldments after heat treatment has increased by about 40%.
Pay attention to controlling process parameters during operation
No matter which method is used, the details of the operation must not be ignored. When performing heat treatment, the heating rate should not exceed 200°C per hour, otherwise new thermal stress will be generated; the cooling should be kept slow, and it is best to cool it with the furnace to below 300°C before taking it out of the oven. For Q345 steel plate riveted weldments with multi-layer and multi-pass welding, the weld can be hammered immediately after one welding, which can also help relieve part of the stress.
When your factory is processing Q345 steel plate rivet weldments, have you ever encountered deformation or cracking problems caused by stress? Welcome to share your experience in the comment area, like it and forward it to let more people see it!
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