Mineralogy and Magnetic Behavior of Yellow to Red Xuanhua-Type Agate and Its Indication to the Forming Condition

Iron oxides/hydroxides are important magnetic minerals to provide information about changes in the forming environment. However, the magnetic behavior in agate has been rarely investigated. In this study, the magnetic behavior of the Xuanhua-type agate with intense yellow to red colors from the Xuanhua District (China) was investigated by temperature dependence of magnetic susceptibility, hysteresis loop, isothermal remanent magnetization and the analysis of remanent coercivity components from the gradient acquisition plot. Yellow goethite and red hematite can be quantitatively identified by XRD and Raman spectroscopy due to their relatively higher content. Results showed that the red, yellow and orange Xuanhua-type agate had different magnetic behavior, and magnetite existed in the yellow and orange ones. Fluid inclusions in such agate had the homogenization temperature of ~168 °C to 264 °C. All results suggested that the dehydration of goethite to form hematite was the main reason for the high remnant coercivity (above 1000 mT) of hematite in the red agate. The co-existence of magnetite and goethite in the yellow and orange agate reflects the transformation from Fe2+ to Fe3+, indicating the change in the redox property of the environment. Unique patterns mainly formed by hematite and goethite make it a popular gem-material with high research value.

Numerical and Experimental Study on Tooth Filling via near Net Shape Extrusion-Forging Process of Multicore Cable Cutter

The near net shape extrusion-forging and the impact of tooth filling computationally simulated and experimentally corroborated. The study plans to search for the finishing forging process's essential station and recognize the unique gear teeth forming in the closed die near net shape extrusion-forging connected with a multicore cable cutter. Due to make sure to realize the Preform types of gear teeth forming, The evaluation index of the height filling ratio (HFR) and the width filling ratio (WFR) methods are offered and simulated with a singular target on process parameters at the gear teeth making. All the objects are regularly investigated and precisely contrasted to experimental examination. The simulations' conclusions have explained the microscopic events after the experimental research. Via matching with experimental measurements, the accuracy of the numerical models has been confirmed. The offered modified geometries (Preform B and C) from the forming process have been eventually offered to achieve a resembling forming condition while lessening making charges.. The mean deviation of HFR was measured as 0.987% and 0.985% for Preform B and C, respectively. Moreover, the mean deviation of WFR was calculated as -0.693% and − 0.74% for Preform B and C, separately.

Springback Suppression of AZ31 Magnesium Alloy Sheet in Draw Bending at Elevated Temperature

In recent years, warm forming of magnesium sheets has been investigated by many researchers since the ductility of the sheets becomes considerably higher due to low CRSS (critical resolved shear stress) at high temperatures (e.g., [1]-[3]). In the present research, the springback of AZ31 magnesium sheet was investigated by performing a draw-bending experiment at several temperatures from 20 °C (room temperature) to 200 °C at drawing speeds ranging from 0.01 to 1.0 mm/s. From the experiment, it was found that the springback was remarkably reduced at 200 °C, especially at a low forming speed, since the flow stress was very low under such a forming condition, and furthermore, the stress relaxation effect was dominant. The effects of temperature and forming speed on springback were discussed.