International audienceThe ASTM E1457-98 standard describes the procedure to determine the master curve da/dt versus C* parameter, for creeping solids. However, the methodology is only to be applied to compact tension (CT) specimens. The European collaborative program CRETE aims at extending the application of the ASTM E1457-98 standard to other types of laboratory specimens. In this paper, an existing database of creep crack growth on 316L(N) stainless steel is utilized, concerning three types of specimens: circumferentially cracked round bars (CCRBs) and double edge notched tensile (DENT) specimens for tensile mechanical loading whereas the classical CT specimen combines tensile and bending loading modes. A modified procedure based on the ASTM E1457-98 standard has been applied to the database, resulting in a unique master curve of da/dt versus C*. The geometry effect is then investigated by introducing the Q* parameter by analogy to the Q parameter in the elastic–plastic J-Q approach

Selective Laser Sintering (SLS) is a 3D printing process on a powder bed that presents a real revolution for many industrial sectors, it allows to produce layer by layer precise prototypes, fast, with high dimensional accuracy and with remarkable mechanical characteristics. This technology uses a laser to fuse polymer micro particles, following the geometry of digitally cut CAD models. However, the external surfaces of the parts produced by this process are characterized by a high degree of roughness due mainly to the properties of the powder, the orientation in the build-up tray and the manufacturing parameters. In this study selective laser sintering experiments were performed with PA12 powders, in order to analyze the optimal process parameters for the realization of parts with minimal roughness. The process parameters chosen for the study were carefully selected and which are laser power, scanning speed, layer thickness and scanning space. The samples were printed in different orientations 0°, 45° and 90°. The Taguchi method was used to study the parameters. Regression equations for each of the orientations were established, these developed a linear relationship between the roughness and the parameters studied.

Selective Laser Sintering (SLS) is a 3D printing process on a powder bed that presents a real revolution for many industrial sectors, it allows to produce layer by layer precise prototypes, fast, with high dimensional accuracy and with remarkable mechanical characteristics. This technology uses a laser to fuse polymer micro particles, following the geometry of digitally cut CAD models. However, the external surfaces of the parts produced by this process are characterized by a high degree of roughness due mainly to the properties of the powder, the orientation in the build-up tray and the manufacturing parameters. In this study selective laser sintering experiments were performed with PA12 powders, in order to analyze the optimal process parameters for the realization of parts with minimal roughness. The process parameters chosen for the study were carefully selected and which are laser power, scanning speed, layer thickness and scanning space. The samples were printed in different orientations 0°, 45° and 90°. The Taguchi method was used to study the parameters. Regression equations for each of the orientations were established, these developed a linear relationship between the roughness and the parameters studied.