Effect of processing rate and stress relief annealing temperature on properties of thick-wall welded cold-rolled titanium tube

Processing rate and stress relief annealing temperature for thick-wall welded cold-rolled titanium pipes The production of thick-wall welded cold-rolled titanium pipes includes press bending, butt welding at both ends of the plate, cold rolling, stress relief annealing (SR treatment), and acid Washing process, etc. In order to accumulate basic data such as the corrosion resistance and mechanical properties of thick-wall welded cold-rolled titanium tubes, and expand its application range, researchers from Datong Special Steel Company studied the effect of processing rate and SR treatment temperature on the microstructure of welded cold-rolled titanium tubes. The influence and the influence of pickling on the microstructure and hydrogen content, and its plasticity was tested. The experimental material is a thin plate that meets the 2nd standard of JsH4600

(1050mmx106mmx3mm), rolled into a tube and welded with TG into a d34mm tube, and then cold rolled into a tube with a three-roll mill with a processing rate of 10%, 20%, and 40%, and then inert atmosphere at 600750℃ SR treatment for 1h during the process.

Finally, the surface layer of about 50pm was removed by pickling in a hydrofluoric acid-nitric acid (tank temperature <80℃) environment to investigate the effect of the above experiments on the product performance.

The experimental results show that no matter what processing rate is used, the microstructure of the pipe weld zone affected by cold rolling has a processed structure. The higher the processing rate, the larger the grains of the weld zone and contain many deformation bands.

Welded cold-rolled titanium tube with a processing rate of 10%, which is subjected to 600, 650℃

After the SR treatment, no recrystallization occurred, and the processed structure remained in the welding zone. However, after SR treatment at 700°C and 750°C, recrystallization occurred, and the microstructure was in a state of coexistence of coarse and fine grains. Welded cold-rolled titanium tubes with a processing rate of 20% and 40%, both the base metal and the weld zone have recrystallized within the experimental SR temperature range, and the recrystallized grain size is almost the same, especially the processing rate of 40% After the pipe is SR treated (600℃x1h), the recrystallized grains are almost the same as the rolled seamless titanium pipe.

The pickling experiment shows that whether or not SR treatment is performed, pickling has no effect on the hydrogen content in the weld zone and the base metal. The flattening experiment shows that the flattening experiment can meet the standard requirements of seamless titanium tubes regardless of whether SR treatment and pickling treatment are carried out.