Influence of steel structure and strength on corrosive-fatigue crack growth in the threshold-close area

The paper presents the results of research into fatigue cracking in the air and on fatigue-corrosive cracking in 3.5% NaCl distilled water solution. The samples of ferrito-perlite 15G2ANb and bainite and marten-sitic 14HNMBCu-special steels were tested. The tests were carried out in the threshold-close area at the two values of stress ratio R=0.2 and R=0.7. The research aimed at recognizing the boundary values of ranges of the stress intensity factors K_th and K_thc in the air and under the corrosive environmental conditions.