Numerical Investigation of Outflow of Non-Metallic Inclusions during Steel Refining in the Ladle.

The article presents the results of numerical simulations of liquid steel flow in the main steelmaking ladle. The paper analyses the mechanism of the outflow of non-metallic Al2O3 and MnS inclusions with diameters in the range of 4-27 µm. The simulations were performed with ANSYS Fluent software. In order to determine the shape and size of non-metallic inclusions formed in the main ladle during steel refining, the collected samples of liquid metal were analysed using a scanning microscope with SEM/EDS and LM (light microscopy). Simulation tests and calculations were carried out for the case of steel refining under the conditions of the Cognor SA HSJ Department in Stalowa Wola (Poland). The presented method of using simulation tests to optimize the technology of steel refining in the ladle is an example. The analysis of the results shows that the gas flow in the metal volume has the greatest impact on the outflow of non-metallic inclusions in the steelmaking ladle.

Investigations of Liquid Steel Viscosity and Its Impact as the Initial Parameter on Modeling of the Steel Flow through the Tundish.

The paper presents research carried out to experimentally determine the dynamic viscosity of selected iron solutions. A high temperature rheometer with an air bearing was used for the tests, and ANSYS Fluent commercial software was used for numerical simulations. The experimental results obtained are, on average, lower by half than the values of the dynamic viscosity coefficient of liquid steel adopted during fluid flow modeling. Numerical simulations were carried out, taking into account the viscosity standard adopted for most numerical calculations and the average value of the obtained experimental dynamic viscosity of the analyzed iron solutions. Both qualitative and quantitative analysis showed differences in the flow structure of liquid steel in the tundish, in particular in the predicted values and the velocity profile distribution. However, these differences are not significant. In addition, the work analyzed two different rheological models-including one of our own-to describe the dynamic viscosity of liquid steel, so that in the future, the experimental stage could be replaced by calculating the value of the dynamic viscosity coefficient of liquid steel using one equation. The results obtained support the use of the author's rheological model for the above; however, this model still needs to be refined and extended to a wide range of alloying elements, mainly the extension of the carbon range.

Prospective outcome assessment of arthroscopic arthrolysis for traumatic and degenerative elbow contracture.

BACKGROUND: The purpose of this study was to evaluate the efficacy of arthroscopic elbow release for both traumatic and degenerative contractures from intraoperative recording through the recovery time until final follow-up. METHODS: The study is based on 54 consecutive patients with extrinsic elbow contracture (traumatic in 31 and degenerative in 23) treated with arthroscopic arthrolysis by a single surgeon in 2011-2015. Range of motion (ROM) and the Mayo Elbow Performance Score (MEPS) were recorded preoperatively; intraoperatively; following release; and in the 1st, 3rd, 8th, 12th, and 26th weeks and at 2 years postoperatively. RESULTS: Significant improvements were noted in extension, flexion, and range of motion, measured both intraoperatively and at all follow-up visits. The greatest improvement in the range of motion was achieved at the time of surgery (from 89° ± 28° to 131° ± 14°, P < .001); it then decreased at 1 week to 103° ± 22° (P < .001) and slowly recovered to reach 124° ± 22° after 2 years. This was better than the preoperative value (P < .001) but worse than the intraoperative value (P = .002). A similar pattern was observed in both traumatic and degenerative contractures. The MEPS improved from 73 ± 12 preoperatively to 93 ± 14 at the final evaluation (P < .001). The ROM and MEPS results at every follow-up were comparable for both traumatic and degenerative contractures. ROM improved regardless of the severity of contracture. CONCLUSIONS: Arthroscopic elbow arthrolysis was similarly efficient in ROM restoration in both traumatic and degenerative contractures and regardless of the severity of contracture. After early deterioration, the achieved gain slowly recovers over a period of 6 months but may not recover to the ranges achieved during arthroscopy.

Effect of arthroscopic techniques on joint volume in shoulder instability: Bankart repair versus capsular shift.

PURPOSE: The evaluation of glenohumeral joint volume in both unstable (with/without laxity) and stable shoulders (subacromial impingement) and volume reduction potential of arthroscopic techniques: (labral anchor repair vs. capsular shift). METHODS: Material was based on 133 patients: anterior shoulder instability without laxity (group I, n = 49), with laxity (group II, n = 22) and subacromial impingement (control group, n = 62) operated in 2010-2011. Group I received arthroscopic Bankart repair, group; II - arthroscopic anterior capsular plication, control group - subacromial decompression. Joint volume was measured by fluid aspiration into the syringe via arthroscope, before and after procedure. Then volume reduction potential was calculated. RESULTS: The following average values of initial joint volume were recorded: group I - 26.8 ml group II - 43.7 ml and the control group - 25.6 ml with significant differences: impingement vs. instability + laxity (p < 0.00001), impingement vs. instability without laxity (p = 0.0001). There was no significant difference between groups I and II. Joint volume was significantly reduced after labral repair (by average of 37 %, 13.8 ml, p < 0.0001). Capsular shift led to an even greater and more significant volume decrease (61 %, 26.7 ml, p < 0.001). Joint volume in the control group was reduced only by 11 %, 3.8 ml (p = 0.046). CONCLUSIONS: Patients with unstable shoulders have enlarged joint volume as compared to patients with subacromial impingement. Arthroscopic techniques lead to a significant joint volume reduction, with the most powerful effect for capsular shift. Level of Evidence - Level 2.