Common Problems And Solutions in Hot Straightening Of Titanium Plates

In the process of titanium plate hot straightening, problems such as springback after straightening, surface oxidation, dimensional deviation and coarse grains are prone to occur due to the influence of raw material quality, process parameters, equipment precision and other factors. Targeted solutions need to be adopted to ensure straightening quality.

 

 

Springback is the most common problem in titanium plate hot straightening. There is no sufficient heating temperature, adequate holding time, proper pressure application or excessively fast cooling rate. It is the reason to lead to incomplete elimination of residual stress.

Solutions: First, raise the heating temperature to the upper limit of the specified range and extend the holding time to ensure uniform internal temperature of the titanium plate and fully release residual stress.

Second, optimize pressure parameters and appropriately increase the pressure holding time to ensure close contact between the titanium plate and the mold or roll body and reduce springback.

Third, choose slow cooling methods to avoid thermal stress caused by rapid cooling; residual stress can be further eliminated through furnace cooling, step cooling and other methods.

Fourth, it is required to make the second hot straightening and adapt process parameters to eliminate springback gradually for titanium plates with large springback.

 

 

Titanium plates are easy to react with oxygen and hydrogen at high temperatures, forming oxide scales and gas absorption layers. Incomplete surface pretreatment may lead to impurity indentation and surface defects.

Solutions: First, clean the surface of titanium plates before hot straightening to remove oil stains, oxide scales and impurities, and grind the gas absorption layer carefully.

Second, take up vacuum heating or protective heating with inert gas to prevent titanium plates from contacting air and reduce oxidation.

Third, control heating temperature and time to avoid intensified oxidation caused by excessively high temperature, and ensure that the thickness of oxide scales and gas absorption layers meets the requirements.

Fourth, make grinding and pickling on the surface of titanium plates after straightening to remove surface oxide scales and repair surface defects.

 

 

The dimensional deviation in unqualified flatness and bending degree is obvious. It is caused by mold dimensional deviation, uneven pressure distribution, non-uniform temperature or improper stacking of plates.

Solutions: First, adjust straightening molds, roll bodies and worktables regularly to ensure dimensional accuracy.

Second, optimize the pressure application method; for large-specification titanium plates, choose uniform or step pressure application to ensure even pressure distribution.

Third, enhance temperature monitoring and adjust heating devices to ensure uniform temperature on the surface and inside of titanium plates. It is used to avoid deformation caused by local overheating.

Fourth, standardize the stacking method of titanium plates, set isolation gaskets reasonably and control stacking thickness to avoid dimensional deviation caused by uneven stress.

 

 

Coarse grains are mainly caused by excessively high heating temperature and overlong holding time, which lead to changes in the metallographic structure of titanium plates and further affect mechanical properties.

Solutions: First, strictly control the heating temperature to avoid exceeding the grain overheating temperature, and determine a reasonable heating range according to the grade of titanium plates.

Second, shorten the holding time and minimize it on the premise of ensuring the elimination of deformation.
Third, optimize the cooling method and accelerate the cooling rate to inhibit grain growth.

Fourth, conduct annealing treatment on titanium plates with coarse grains to adjust the metallographic structure and restore mechanical properties.

 

Ruihang is a manufacturer of titanium and non-ferrous metal products, supplying a full range of titanium bars with international standard. For more details, contact us by email: Sam.Rui@bjrh-titanium.com.