What are the hazards of welding stress?
Welding stress can have significant negative effects on the integrity and durability of welded structures. Understanding these hazards is crucial for preventing structural failures and ensuring the quality of welded components.

stress corrosion cracking
1.Causing Welding Cracks
Welding stress, when combined with temperature fluctuations, structural rigidity, and metallurgical changes, can reach a level where it becomes a major cause of welding cracks, such as hot cracks and cold cracks. These cracks compromise the structural integrity, pose safety risks, and can result in costly repairs or the scrapping of components.
2.Reducing Structural Load-Bearing Capacity
(1)Residual and Working Stress Combination: The combination of residual stress from welding and operational stress increases the overall stress level on the structure. This effectively reduces the load-bearing capacity or the safety margin of the structure’s strength.
(2)Exceeding Material Yield Limit: When the stress level surpasses the material’s yield strength, it can cause tensile plastic deformation in the joint area, consuming the material’s ductility.
(3)Tri-Axial Tensile Stress in Thick-Walled Structures: In thick-walled welded areas, particularly at intersections of complex welds or where defects exist, tri-axial tensile stress can form. This reduces the material’s ability to deform plastically and may become the starting point for brittle fracture under low stress.
(4)Deformation Under Low-Cycle Fatigue Loads: High tensile residual stress can cause a certain degree of deformation in structures subjected to low-cycle fatigue loads over long periods, affecting the overall durability of the component.
3.Inducing Stress Corrosion
The presence of tensile residual stress increases the likelihood of stress corrosion cracking (SCC) when the structure is exposed to corrosive environments. This can lead to stress corrosion and even low-stress brittle fractures, further compromising the structure’s integrity.

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4.Affecting Dimensional Stability
Residual stress can also impact the dimensional stability of welded structures, especially those that require post-weld machining. The machining process can disturb the balance of internal stress, causing deformation or instability in the processed dimensions.
Understanding the hazards associated with welding stress highlights the importance of stress management techniques, such as preheating, post-weld heat treatment (PWHT), and controlled cooling rates, to minimize these risks and enhance the performance and longevity of welded structures.