Abrasion resistance of surface-modified steels used for artillery weapon barrels
A barrel is one of the most tribologically and thermally loaded parts of artillery weapons. The influence of the salt bath nitrocarburizing and hard-chrome plating of three steels used for artillery barrels on their abrasion resistance is studied in this paper. The tested steels are 42CrMo4, 30CrNiMo8, and 36CrNiMo4 in the initial quenched and tempered state. The test results from the ''dry sand/rubber wheel'' method, after 700 m of wear path, showed that the hard-chrome plating of 42CrMo4 and 30CrNiMo8 steels improved their abrasion resistance. In addition, reduced abrasive wear of 42CrMo4 steel samples was also achieved by nitrocarburizing. Hard chrome-plated samples exhibited good wear resistance due to their greater hardness and bigger thickness of the compound zone in comparison with that obtained on nitrocarburized samples.
Simulation Approach for Surface Roughness Interval Prediction in Finish Turning
Existing simulation models used in predicting the surface roughness of a workpiece in finish turning are based on an ideal circular cutting tool nose profile. This leads to a single predicted roughness value for a given set of input parameters. In this paper, a simulation approach that considers the random tool nose profile micro-deviations as well as the tool chatter vibration to predict a roughness interval is proposed. The nose profiles used in the simulation were extracted from images of the real cutting tool inserts using sub-pixel edge location. The chatter vibration signal was reconstructed from the measured signals and was superimposed onto the extracted nose profile. The roughness data were computed from 24 simulated workpiece surface profiles and used to determine the 95 % roughness prediction interval. Comparison with the experimental results showed that 100 %, 96 % and 96 % of the Rt, Ra and Rq roughness values obtained experimentally fell within the predicted roughness intervals. (Received in March 2015, accepted in September 2015. This paper was with the authors 1 month for 1 revision.)
Constitutional Identity in the EU— A Shield or a Sword?
This Article consists of five sections. In the first section, it describes why identity questions matter, particularly in Europe. In the second section, the Article tackles the issue of multiple structural ambiguities affecting the concept of constitutional identity in the European constitutional vocabulary. In the third section, the Article explores trends concerning the use of constitutional identity in the European legal discourse and practice, including the development of alternative interpretations and applications of the notion of constitutional identities in the Member States. The fourth section of the Article combines the analytical accounts outlined in the second section with the trends identified in the third section, contending that different conceptions and applications of constitutional identity have varying effects on the European composite constitutional adjudication system and that the institutional and procedural framework should be calibrated accordingly. The final section of this Article draws some conclusions.