What Is Titanium Stress Relief Annealing

Recently, a number of customers have mentioned questions related to the need for stress annealing in subsequent processing. I am now using our official website to answer questions and how to control stress annealing in our materials. Stress annealing is also known as incomplete annealing. Its purpose is to eliminate internal stresses generated during cold deformation, cold molding, welding, etc.

The annealing temperature should not be too high, generally lower than the recrystallization temperature of 50~200 ℃, about 450~650 ℃. The specific temperature should be set according to different materials.
As mentioned above, the cold deformation of titanium accumulates a large amount of distortion energy, generating internal stresses, resulting in titanium "work hardening". When annealed incompletely, titanium releases the distortion energy and removes the internal stresses. At this time, the internal structure of titanium is generally restored, the shape and size of titanium crystals back to the original state, "work hardening" disappears, into a soft state, the cold deformation of the substable state back to a stable state.

Incomplete annealing of β-type titanium alloys sometimes causes aging effect or aging effect, and solid solution treatment can be used to eliminate stress.

The main process parameters of stress relief annealing are annealing temperature and holding time, which affect each other. Sometimes appropriate to increase the temperature, shorten the holding time can also achieve the same effect, and vice versa. The main factors affecting the two are the thickness and material of the workpiece, the original residual stress and the final degree of stress relaxation. the higher the annealing temperature of the TC4 workpiece, the longer the holding time, the more complete the internal stress relief. By analogy, titanium and titanium alloys conform to this law.

Stress relief annealing cooling method is generally used air cooling, sometimes also used furnace cooling.

It should be noted that the stress relief annealing of titanium weldments is often carried out simultaneously with the subsequent heat treatment. Stress relief annealing of cold-formed titanium parts and subsequent heat treatment for uniform treatment. The stress relief annealing of cold-formed titanium parts is carried out simultaneously with the heat straightening process, which is conducive to energy saving.TC4 titanium alloy can be air-cooled at a stress relief annealing temperature of 600°C after deformation processing. The microstructure obtained by stress relief annealing and normal annealing is unrecrystallized or partially recrystallized.