I’m seeking help from experts to analyze the cause of the cracking
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Cracks appeared after welding the flange and reinforcement plate – was it caused by excessive welding stress or something else?
All experts are encouraged to actively participate in the analysis and discussions
It should not be just welding stress; the flange may have significant internal stresses from its manufacturing process, which remain unresolved. When these are combined with welding stress, the flange is prone to damage. It must have been a coincidence
You can ask a machining engineer to analyze it
It’s that serious – can it still be repaired?
I’m not very proficient in this area; it seems like it’s related to the manufacturing process, with stress not being properly eliminated, which leads to this issue
Did you make that small hole yourself?
What is the temperature around this place? Is the cooling process happening too quickly?
This is quite rare. A few comments: 1. The location of this opening is problematic – it’s too close to the flange. Check the standards; it may not comply with the regulations. Is there a requirement of 150mm? 2. Reinforcement is applied at the weld site; although this is acceptable, it should be avoided as much as possible. The reinforced welds need to undergo 100% inspection, and it’s difficult to inspect them given their proximity to the flange. 3. The flange is a forged piece with a thick wall, high internal stress, and high hardness, which makes welding difficult. Delayed cracks are likely to occur. Generally, strict requirements apply to welding forged parts, especially those with large thicknesses; butt welding is the preferred method, and preheating is necessary for thicker pieces. 4. Since the flange is so thick, this part does not require reinforcement. In summary, the reason for the cracks in your forging is the lack of preheating during welding, as well as the absence of post-weld heating; this results in high residual stresses. In cases where the thickness of the forging is large, temperature differences along the thickness direction also cause significant stresses. Moreover, the forging has poor toughness, which leads to cracking under the combined effect of these various stresses. Recommended solution: The location of the holes is incorrect; they should be placed further away from the welds. The reinforcement should not extend to the flange, but only up to the weld area, without covering the forged part of the flange. Preheating and post-heating before welding. In this way, cracking is unlikely to occur.