Surface integrity analysis of ADI and IADI after manufacturing processes

M.E. FURNO; A.D. SOSA; D.A. COLOMBO

Darmstadt

Congreso; Material Science Engineering Congress; 2018

German Materials Society

Ductile iron(DI) is a candidate material for the manufacturing of mechanicalparts when low costs, recyclability and reliability are needed.Italso offers an excellent weight to strength ratio, comparable withmore expensive light alloys. Mechanical properties of DI can bewidely changed by heat treatment, to get other variants likeaustempered ductile iron (ADI) and intercritical austempered ductileiron (IADI).ADI parts are common in  supports, pumps andengines exposed to marine conditions. IADI is a most recentdevelopment for mechanicals components that need more toughness thanADI parts. When considering thin wall parts, the highersurface-to-volume ratio makes surface properties essential forquality and service performance.The operations required for themanufacturing of mechanical parts, such as turning, grinding andcoatings deposition, among others, modify the properties andcharacteristics of their surfaces. The proper use of processparameters and the knowledge of their effect on surface propertiescan lead to optimize the service behavior of them.This workstudies the surface characteristics (hardness, topography, residualstresses, microstructure) of DI samples subjected to differentmanufacturing processes (heat treatment, turning, grinding andcoatings deposition) and its correlation with shape distortion andother properties such as corrosion and wear resistance.Surfaceintegrity of samples was determinated by means of microindentationtests, surface scanning,  X-ray diffraction  optical andscanning electron microscopy. Furthermore, corrosion and wearbehaviour of surfaces were analized by means of electrochemicalexperiments on sea water and unidirectional sliding - rolling contactfatigue tests. The analysis was carried out by comparing theproperties of the material before and after the manufacturing processapplied.The results indicate that machining (both conventionaland abrasive) and coatings deposition produces surface hardening,compressive residual stresses in most cases and topographic changesat macro and micro-scale. In addition, machining generates plasticdeformation in surface and sub-surface layers and shape distortion inthin wall samples, diminishes the corrosion resistance and does notaffect significantly the wear resistance while coatings depositionimproves in most cases the corrosion and wear behaviour.p { margin-bottom: 0.25cm; direction: ltr; line-height: 115%; text-align: left; }p.western { }p.cjk { }a:link { color: rgb(5, 99, 193); }a.ctl:link { font-family: "Times New Roman"; }