PROPIEDADES A FATIGA DE LOS ACEROS INOXIDABLES DÚPLEX LEAN ENVEJECIDOS

R. STRUBBIA; M. SENNUOR; S. HEREÑÚ

Congreso; 16o Congreso Internacional de Metalurgia y Materiales SAM-CONAMET 2016. Simposio Materiales y Tecnologías para la Industria Me- talmecánica y Aeroespacial.; 2016

Duplex stainless steels (DSS) can be found in many applications that involved elevated temperature, as those related to energy conversion or automotive exhaust systems. In the range between 400ºC and 500° C DSS steels suffer a hardness increase together with a loss of ductility and toughness. This phenomenon, known as 475ºC embrittlement, is attributed to the spinodal decomposition (SD) of the ferritic phase in regions rich in iron (α) and rich in chromium (α´). The newly developed lean duplex stainless steels (LDSSs), with low Ni content, have become a cost attractive alternative while maintaining good mechanical properties, high thermal conductivity and corrosion resistance [1]. Furthermore, it has been reported that a decrease in Ni content decelerates the spinodal decomposition [2,3]. However, there are only few studies about SD in LDSSs [4], and to date there is no investigation addressing the cyclic behavior of aged LDSS. The purpose of this work is to study the influence of aging at 475°C for 100 hours on the cyclic behavior of two LDSSs (AL 2003 and LDX 2101) with different Ni content thermal. The results are discussed in correlation with the microstructural study by both techniques Scanning Transmission Electron Microscopy (STEM)) and Energy Dispersive Spectroscopy (EDS), as well as hardness and residual stress measurements in each phase. In thepresent work is found that although in the ferrite phase of both LDSSs the spinodal decomposition is similar,a more pronounced detrimental effect on the fatigue properties of the steel with higher nickel content is observed.