Harm of welding stress in mid-frequency spot welder

The harm of welding stress of mid-frequency spot welding machine is mainly concentrated in six aspects: 1, welding strength; 2, welding stiffness; 3, stability of welding parts; 4, processing accuracy; 5, dimensional stability; 6. Corrosion resistance. The following small series for you to introduce in detail:

Effect on strength: If there are serious defects in the high residual tensile stress zone, and the welding part is operating at a lower brittleness transition temperature, the welding residual stress will reduce the static load strength. Under the action of cyclic stress, if the residual tensile stress exists at the stress concentration, the welding residual tensile stress will reduce the fatigue strength of the weldment.

Influence on stiffness: the welding residual stress and the stress caused by external load superposition, may make the welding part yield in advance and produce plastic deformation. The stiffness of the weldment will be reduced as a result.

Influence on the stability of the pressure welded parts: when the welding rod is under pressure, the welding residual stress and the stress caused by the external load are superimposed, which may make the rod local yield or make the rod local instability, and the overall stability of the rod will be reduced. The influence of residual stress on the stability depends on the geometry of the member and the distribution of internal stress. The influence of residual stress on non-closed section (such as I-section) is greater than that of closed section (such as box section).

Influence on machining accuracy: The existence of welding residual stress has different degrees of influence on the machining accuracy of weldparts. The smaller the stiffness of the weldment, the greater the processing amount, and the greater the impact on the accuracy.

Influence on dimensional stability: The welding residual stress changes with time, and the size of the weldment also changes. The dimensional stability of welded parts is also affected by the stability of residual stress.

Effect on corrosion resistance: Welding residual stress and load stress can also cause stress corrosion cracking.