The physical characteristics: controlled residual compressive stress, grain refinement and grain size reduction. Low and high cycle fatigue are enhanced and have been documented to provide increases up to ten times greater than non-UIT specimens. UIT improves the working life of welding joint effectively. It leads steel welding joint to increase fatigue strength by *0~**0% and fatigue life by *0~**5 times. It also leads TiAl welding joint to increase fatigue strength by *6~*8% and fatigue life by 5~*4 times.
