Tsinghua University conducted CTOD tests on common bridge steels Q370qE and Q345qD, and calculated the CTOD values of materials under brittle fracture, ductile brittle failure and ductile failure respectively, as the basis for revising the conventional impact toughness standard.

1、 The application scope of internal thread pneumatic ball valve The internal thread pneumatic ball valve and butt welding pneumatic ball valve are applicable to various pipelines with PN1.0~4.0MPa, operating temperature of - 29~180 ℃ (the sealing ring is reinforced polytetrafluoroethylene) or - 29~300 ℃ (the sealing ring is aligned polystyrene), and are used to cut off or connect the medium in the pipeline. Different materials can be used for water, steam, oil, nitric acid, acetic acid and other media.