Perepichai A. Evaluation based on the criterion of fracture mechanics static strength of circumferential welds steam lines with a valid fusions and recommendations for their repair

Thesis is devoted to the assessment based on the criterion of fracture mechanics static strength of circumferential welds steam lines with a valid fusions and development of technological advice. The article describes the method of calculation of the stress- strain state in the region above fusions using the finite element method . It is shown that in the circumferential weld metal fusions of roots in the residual state after welding to form dangerous state of stress in terms of opportunities for education and further quasibrittle natural crack propagation from the top of lack of fusion. Developed a new approximate method for calculating the stress intensity factors , which allows you to define the parameter in the most dangerous point of the inner surface of the annular crack elipsoobraznoy fusions weld root in the force field of welding residual stress and performance . Found that welding circumferential weld is not one , but three passes substantially changes the nature of the distribution of axial residual welding stresses in the zone above the top of lack of fusion , thereby making it impossible to crack propagation and in a manner guaranteed to static strength of joints steam line .