Resumo

CASTILLA C, Enrique; GUERRERO, Aimé  e  FERNANDEZ, Norberto. EVALUATION OF THE BEHAVIOR OF BUTT-WELDT LOW-CARBON BARS OF STEEL AND SUBJECTED TO SEVERE CYCLES OF AXIAL LOAD. IMME [online]. 2001, vol.39, n.3, pp.1-12. ISSN 0376-723X.

ABSTRACT This study evaluates the behavior of butt-welded low-carbon reinforcing bars (ASTM A-706) subjected to severe cycles of pulsating load. The tests covered 95 bars of all commercial diameters between #4 and #8, welded according to specifications set forth in AWS D1.4. Of these, a total of 55 were of thermo-treated steel and the remaining 40 were of micro-alloy steel. Once failure was reached in some of the tested specimens, the micro-structural and fractographic characteristics of the welded joints were determined using electronic microscope scanning and X-ray dispersive energy. The results suggest that micro-alloy steel bars can be welded at room-temperature without affecting their earthquake-resistant properties. In the case of thermo-treated steel bars, larger diameters (equal or greater than #6) show undesired behavior for earthquake-resistant use, perhaps because they are more sensitive to hydrogen cracking. Conclusions are also drawn as to the quench depth for thermo-treated steel bars which will guarantee ductile behavior when welded at room temperature

Palavras-chave : Steel; thermo-treated; micro-alloy; welding; bars; freight train; brittle failure; ductile failure.