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Purpose The mechanical characterization of selective laser melting (SLM) parts is an industrial challenge. This paper aims to propose a methodology to control the fatigue life of 17-4Ph stainless steel by selecting the most relevant manufacturing parameters: i.e. laser power, laser travel speed, hatch spacing and laser defocusing. Design/methodology/approach A rough and refined design of experiment (DOE) is carried out to target the best combination of process parameters. A response surface model is then constructed to predict the parameter combination that optimizes the fatigue performance. Findings This study results show that the fatigue limit of the specimens manufactured by SLM (471.7 MPa at 107 cycles) has reached near 90% of the value found in samples machined from a bar. This demonstrates the applicability of the method proposed to optimize the SLM process and control the fatigue life of 17-4Ph stainless steel. The study results are compared with other research works and provide an increase of 18% to the fatigue limit. Originality/value This study showcases a DOE methodology to optimize the SLM parameters to achieve fatigue performance as great as that of solid 17-4Ph stainless steel.

The usual formulation used for determining stresses by X‐ray diffraction with a flat specimen is not valid when the sample has a curved surface. In the first paper of this series [François et al. (1995). J. Appl. Cryst.28, 761–767], a general formulation was presented, showing that two effects arise simultaneously: a translation and a rotation effect. In the present paper, analytical formulae, derived from the general expression and valid under certain assumptions, are given. They exhibit a linear relation between the measured strain and sin2ψ and they can be used in many practical cases. Experimental and numerical examples of the use of the simplified and the general formulation on thick and thin wires, thin layers on wires, convex and concave specimens, and isotropic and textured samples are given. The range in which the classical and the present formulation are valid is also studied.

In contrast to measurements of the dimensions of machined parts realized by machine tools and characterized by CMMs, software results are not fully traceable and certified. Indeed, a computer is not a perfect machine and binary encoding of real numbers leads to rounding of successive intermediate calculations that may lead to globally false results. This is the case for poor implementations and poorly conditioned algorithms. Therefore, accurate geometric modelling and implementations will be detailed. Based on the works of National Metrology Institutes, the problem of software traceability will also be discussed. Some prospects for this complex task will finally be suggested.

Stress analysis by X-ray diffraction, usually performed on a specimen with plane geometry, becomes very difficult on more complex surfaces. A model is proposed to calculate the six independent components of the stress tensor for cylindrical symmetry. The mathematical approach described highlights two distinct effects that modify values of measured strain by X-ray diffraction, a rotation effect and a translation effect. The X-ray absorption by the material is taken into consideration and two models are proposed to undertake the mathematical processing on thick materials and thin layers. It is equally possible to take into account, for example, crystallographic texture and experimental features as q~ oscillations., Examples and applications will be given in paper II [Dionnet, Franqois, Sprauel & Nardou (1995). In preparation].

International audienceThe authorities of the standards organization International Organization of Standardization (ISO) advocate mastering any uncertainties in all parts of the industrialization process. In the three-dimensional (3D) measurement process, uncertainty is usually obtained at the end of a battery of tests. It is defined as a whole because it includes several types of errors, known systematic components, unknown systematic components and random components. Automated calculations of uncertainty can be made based on statistics. This method is based on statistical concepts, which are in accordance with " The Guide to the expression of the uncertainty in measurement " (GUM). It also enables us to generate uncertainties on the verification of ISO specifications (or specs in the ISO directives). In the course of this article, a usage will be presented that takes the knowledge of uncertainties into account: this usage will help the operator to take a decision on the conformance of a mechanical part in reference to its conformance to geometric tolerance

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