HYDROGEN-INDUCED COLD CRACKS IN WELDED JOINTS OF HIGH-STRENGTH LOW-ALLOYED STEELS (Review)

摘要

Possibility of development of hydrogen-induced cold cracks in welded joint depends on series of interconnected and complex physical phenomena. Work represents a short review of investigations carried out in the E. O. Paton Electric Welding Institute on study of processes of hydrogen absorption by metal, its diffusion in the welded joint considering kinetics of temperature gradient, hydrogen traps and residual stresses. Peculiarities of hydrogen diffusion in strain-free and plastically deformed metal were studied by experiment-calculated methods. Results of experiment-calculation investigations and mathematical modelling of mechanisms of generation and growth of hydrogen-induced cracks in welded joints on micro- and macrolevel are stated. It is shown with high reliability that interaction of hydrogen with dislocations makes the basis of mechanism of hydrogen embrittlement. Hydrogen influences nucleation and growth of microcracks in metal making coalescence of dislocations easier that result in localizing of plastic strain under effect of hydrogen. As it is showed by computer modelling of development of microdefects in metal, the reduction of grain size, at other factors being equal, increases metal sensitivity to negative influence of hydrogen. Mechanism of crack growth in metal containing hydrogen is proposed considering effect of hydrogen-enhanced localized plasticity.