TY - JOUR
T1 - Cold hole expansion effect on the fatigue crack growth in welds of a 6061-T6 aluminum alloy
AU - Viveros, K. C.
AU - Ambriz, R. R.
AU - Amrouche, A.
AU - Talha, A.
AU - García, C.
AU - Jaramillo, D.
N1 - Funding Information:
This article was supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT) , project CB177834. SIP-IPN is also acknowledge.
PY - 2014/11
Y1 - 2014/11
N2 - Compact test specimens were extracted from a 6061-T6 aluminum alloy welded plate with a thickness of 9 mm to analyze the cold hole expansion effect on fatigue crack growth tests conducted in mode I cyclic loading. At R = 0.1, a sharp crack in base metal, weld metal and heat affected zone was propagated from 17 to 24 mm. The fatigue crack growth at 24 mm (α = a/W = 0.3) was delayed by drilling a hole at the crack tip and applying a cold hole expansion of 4.1%. The residual stress fields due to cold hole expansion were determined with the finite element method. The fatigue crack growth testing was continued up to a crack length of 35 mm (α ∼ 0.43) at the same R, and crack opening displacements of the post-expansion crack were also determined with the finite element method. The results were expressed in terms of crack length versus number of cycles, as well as, fatigue crack growth rate as a function of applied and effective stress intensity factor range. The cold hole expansion contributed to delay the fatigue crack growth in base metal, and to a lesser extent in the weld metal and heat affected zone. A crack closure effect was determined by means of load versus crack opening displacement curves of the post-expansion crack, which was, completely or partially closed, in welded zones with compressive residual stress fields. The fracture surfaces of each welded zone were analyzed to elucidate the crack nucleation zone and its relation with the residual stress field. In all cases the crack was initiated at the surface of the specimen where the residual stresses were positive.
AB - Compact test specimens were extracted from a 6061-T6 aluminum alloy welded plate with a thickness of 9 mm to analyze the cold hole expansion effect on fatigue crack growth tests conducted in mode I cyclic loading. At R = 0.1, a sharp crack in base metal, weld metal and heat affected zone was propagated from 17 to 24 mm. The fatigue crack growth at 24 mm (α = a/W = 0.3) was delayed by drilling a hole at the crack tip and applying a cold hole expansion of 4.1%. The residual stress fields due to cold hole expansion were determined with the finite element method. The fatigue crack growth testing was continued up to a crack length of 35 mm (α ∼ 0.43) at the same R, and crack opening displacements of the post-expansion crack were also determined with the finite element method. The results were expressed in terms of crack length versus number of cycles, as well as, fatigue crack growth rate as a function of applied and effective stress intensity factor range. The cold hole expansion contributed to delay the fatigue crack growth in base metal, and to a lesser extent in the weld metal and heat affected zone. A crack closure effect was determined by means of load versus crack opening displacement curves of the post-expansion crack, which was, completely or partially closed, in welded zones with compressive residual stress fields. The fracture surfaces of each welded zone were analyzed to elucidate the crack nucleation zone and its relation with the residual stress field. In all cases the crack was initiated at the surface of the specimen where the residual stresses were positive.
KW - 6061-T6
KW - Cold hole expansion
KW - Fatigue crack growth
KW - Finite element simulation
KW - Welding
UR - http://www.scopus.com/inward/record.url?scp=84903142435&partnerID=8YFLogxK
U2 - 10.1016/j.jmatprotec.2014.05.030
DO - 10.1016/j.jmatprotec.2014.05.030
M3 - Artículo
SN - 0924-0136
VL - 214
SP - 2606
EP - 2616
JO - Journal of Materials Processing Technology
JF - Journal of Materials Processing Technology
IS - 11
ER -