Numerical and experimental analyses on the indentation of coated systems with substrates with different mechanical properties

In this work, the indentation of coated systems was studied in terms of the effect of the mechanical properties of the substrate on the film fracture behavior. Both experimental and finite element modeling analyses were conducted to study the phenomena that occur when an indenter with Rockwell C geometry applies normal loads of 400 and 1500 N on titanium nitride (TiN) films deposited onto different steel substrates: AISI 4140 with a hardness of 240 HV and AISI M2 with hardness of 260 HV and 850 HV. Experimental results indicated the formation of circular cracks close to the contact edge of specimens, for 4140 substrates, and radial cracks close to the contact edge, for the M2 substrates, independently of the substrate hardness. Both finite element modeling (FEM) and experimental analyses were able to correlate these results with the amount of substrate pile-up close to the indentation edge, which affects the contact stress distribution during indentation.