Recently, Ti–6Al–2Sn–4Zr–2Mo (Ti-6242), a Ti-based alloy that combines weldability, high temperature stability and creep resistance has been qualified for serial production using laser powder bed fusion processing (L-PBF), [1]. Compared to the most common Ti-6Al-4V (Ti-64), also used in aeroengine and motorsport components, Ti-6242 is preferred for higher temperature applications, i.e. up to 540°C. Differently to Ti-64, the fatigue properties of L-PBF Ti-6242 available in the open literature are scarce.

This contribution is aimed at filling this gap by presenting the results of an extensive experimental campaign on L-PBF Ti-6242 developed using an innovative and efficient fatigue test methodology, [2]. Plasma atomized alloy powder and an SLM 280HL twin system (SLM Solutions Gmbh Germany) working at a layer thickness of 60 um were used to produce smooth prismatic specimens oriented in different directions with respect to build direction by an experienced service provider. The ultimate tensile strength (UTS) of 1100MPa and a yield strength (YS) of 100MPa, that is comparable to forged Ti6242, were achieved after solution heat treatment (above the beta-transus temperature) and ageing, [1].

The fatigue specimens were tested with surfaces in the as-built condition because surface machining and polishing is not viable or even possible when an AM part geometry is complex. The relatively high roughness of as-built surfaces of metallic AM parts is known to be influenced by a number of factors such as powder quality, process parameters, layer thickness, surface orientation with respect to build etc.. Therefore, the test surface of the fatigue specimens printed along different directions were characterized by roughness parameters before testing.

The high cycle fatigue behavior was determined by applying plane cyclic bending at a cyclic load ratio R=0 at a frequency of 25 Hz. Tests were interrupted when cycles reached 2x106 without failure. The S/N trends originally revealed the anisotropic fatigue behavior of L-PBF Ti6242 with fatigue strengths varying in the 200 MPa – 350 MPa range. This anisotropic behavior is compared to that of L-PBF Ti-64 reported elsewhere, [3].