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The present paper investigates the redistribution of residual stresses resulting from manufacturing steps in the production of cold-drawn AISI 1045 steel bars. The main steps in this process chain are the pre-straightening of coiled material, shot-blasting, cold-drawing, cutting, and final straightening with crossed rolls. Drawing and final straightening parameters were changed to evaluate their influence on the residual stress distributions as measured by X-ray diffraction and hole-drilling techniques after the different manufacturing steps. It was found that, depending on the manufacturing parameters, the pre-straightened material generates nonhomogeneity of residual stresses which can remain even after the last manufacturing steps. The angle between the crossed rolls in the final straightening has a high influence on the homogeneity of the surface residual stresses. Both the drawing angle and the angle between the crossed rolls significantly affect the residual stress depth distribution.

In this study, the distortion of steel shafts was investigated before and after induction hardening. Several essential influencing factors in the manufacturing process chain regarding cold drawing, cutting method, notches on the shafts, and induction hardening were analyzed by design of experiment (DoE). Further necessary examinations of microstructures, hardness profile, segregation of chemical composition, and residual stress state were conducted for understanding the distortion behavior. The results of the statistical analysis of the DoE showed that the drawing process is the most important factor influencing distortion. The surface hardening depth of induction hardening is the second main factor. The relationship between inhomogeneities in the work pieces and the distortion was finally discussed.

For the first time, the influence of gas mixture on first damage resistance of a plasma nitrided DIN 18MnCrSiMo6-4 bainitic steel was investigated. Samples were nitrided at 500 °C with three different N 2 -H 2 gas mixtures, containing 5, 24, and 76 vol.% N 2 . Samples were characterized concerning the resulting roughness, microstructure, compound layer's phase composition, residual stresses in the diffusion zone, and surface hardness. Tribological ball-on-flat tests were carried out in reciprocal mode using zirconia as ball material for friction coefficient and the compound layer resistance until the first damage. The test results were evaluated statistically by analysis of variance (ANOVA). As the amount of nitrogen in the gas mixture decreases, the ε-Fe 2-3 (C)N content in the compound layer decreases. A γ'-Fe 4 N monophasic compound layer was achieved at 5 vol.% N 2 gas mixture. The diffusion zone as expected presented compressive residual stresses with the highest values near the surface. In the tribological tests, better results were obtained for 5 and 24 vol.% N 2 in the gas mixture as higher amounts of γ'-Fe 4 N were formed. The 76 vol.% N 2 gas mixture led to a brittle behavior, due to the biphasic compound layer (γ'-Fe 4 N and ε-Fe 2-3 (C)N) with a predominant content of ε-Fe 2-3 (C)N.

Epilepsia partialis continua is often refractory to antiepileptic medication and its causal relation to peripheral sensory stimuli has only rarely been suggested. We report a man who received surgery for temporal lobe epilepsy 10 years ago, who presented “de novo” epilepsia partialis continua following mild traumatic injury of the left hand. Continuous myoclonus of the left upper limb started the day after injury and persisted unabated for several weeks. Non‐invasive evaluation was inconclusive. Acute electrocorticography during surgery under local anaesthesia revealed continuous, rhythmic spiking over the right sensorimotor cortex. Tailored excision of the posterior bank of the motor and adjacent sensory cortex immediately stopped the continuous myoclonus. Histopathology showed abnormal radial lamination and was compatible with focal cortical dysplasia type IA. Epilepsia partialis continua did not recur for seven years. Afferent stimuli from peripheral injury can disinhibit hyperexcitable sensorimotor cortex leading to epilepsia partialis continua. [Published with video sequences online]

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