The welding function of cutting titanium plate should reflect these aspects:
(1) High-temperature cracks
The high-temperature cracks mentioned here refer to cracks related to welding. High-temperature cracks can be roughly divided into condensation cracks, micro-cracks, HAZ (heat-affected zone) cracks, and reheat cracks.
(2) Low-temperature cracks: low-temperature cracks sometimes occur in martensitic cut titanium plates and some ferrite cut titanium plates with martensite arrangements. Because the main cause of its occurrence is hydrogen dispersion, the degree of restraint of the welded joint, and the hardening arrangement therebetween, the solution should be to reduce the dispersion of hydrogen during the welding process and appropriately perform preheating and post-weld heat treatment, and reduce the degree of restraint.
(3) σ phase embrittlement: austenitic cut titanium plate, ferrite cut titanium plate, and dual-phase titanium plate are prone to σ phase embrittlement. Because a few percent of the alpha phase is separated in the arrangement, the tolerance is significantly reduced. “Phases are usually separated in the range of 600-900℃, especially around 75℃. As a preventive method to avoid the occurrence of phases, the content of ferrite should be reduced as much as possible in the austenitic cut titanium plate.
(4) Embrittlement at 475°C. When holding for a long time near 475°C (370-540°C), the Fe-Cr alloy is decomposed into α solid solution with low chromium concentration and α’solid solution with high chromium concentration. When the chromium concentration in the α’solid solution is greater than 75%, the deformation changes from slip deformation to twin deformation, and then embrittlement at 475°C occurs.