This work of thesis is part of a study of steel development API X80 and the objective of this work was to evaluate superficial the steady growth of one crack located in the heat affected zone (HAZ) of together the longitudinal one gotten by the process of submerged arc. Two pertaining steel API had been studied 5L X80 to the systems NbCr and NbCrMo. Considering that pipes operate under high pressures, generating a severe state of tension under a present defect or crack in the material imperfection of the structure can occur. In this way, one becomes necessary to study the nature of these cracks and the potential of growth, being thus allowed to control and to foresee the steady growth of crack. To evaluate the behavior of crack, the methodology of integral J was used. This objective methodology to evaluate and to foresee the behavior to the breaking. The results waited in the assay of integral J are the attainment of the curve of resistance J-R and the value of the JIc, which represents the value of J in the beginning of the steady growth of crack.