Abstract

BERRIOS-ORTIZ, JONATHAN ANTONIO; STAIA, MARIANA H  and  PUCHI-CABRERA, ELI SAUL. Fatigue behaviour of an annealed AISI 1045 steel coated with Ni-P autocatalytic deposits. Rev. Fac. Ing. UCV [online]. 2005, vol.20, n.1, pp.5-16. ISSN 0798-4065.

A study has been carried out in order to investigate the effect of thickness and post heat treatment of an autocatalytic electroless Ni-P deposit (EN), plated on an annealed AISI 1045 steel, on the fatigue behavior under rotating bending conditions. The thickness of the coating was of approximately 7, 17 and 37 μm. The post heat treatments were: firstly, at 200°C for 60 min. (PHT-1) and secondly at 200°C for 60 min. followed at 400°C for 60 min. (PHT-2). It has been determined that the deposits have a mean hardness of 663 and 1044 KHN₅₀, after PHT-1 and PHT-2 respectively. Also, it has been found that the flow stress and the ultimate tensile true stress decrease slightly, whereas the true fracture stress decreases significantly as the thickness of the deposits increases for both PHT. It has been determined that the deposit of 7 μm in thickness after PHT-1 does not give rise to any significant change in fatigue life, as compared with the uncoated substrate. Also, it has been observed that as the thickness of the EN plating increases, the fatigue life of the coated samples decreases markedly. The deposits subjected to the PHT-2 treatment give rise to a more pronounced decrease in fatigue life as compared with the deposits subjected to the PHT-1, although such an effect is less marked as the  thickness of the coatings increases.

Keywords : autocatalytic deposition; fatigue life; EN coatings.