RESUMEN
The microstructural evolution of SK85 pearlitic steel cold-rolled up to a 90% rolling reduction was characterized by scanning electron microscopy with electron backscattered diffraction (EBSD) and X-ray diffraction (XRD). SK85 steel exhibits excellent cold rolling performance. The interlamellar spacing of pearlite is refined obviously and a tensile strength of 2318 MPa can be reached for SK85 steel after 90% rolling reduction, an increase of 83% from 1264 MPa before rolling. The EBSD observation indicates that the {001} <110> texture becomes pronounced at a 90% rolling reduction in cold-rolled Sk85 steel. A propagation and multiplication of dislocations occur during rolling as the kernel average misorientation (KAM) angles significantly increase from 0.72° to 2.11°. The XRD analysis reveals that bcc ferrite is transformed into a bct structure at a 90% rolling reduction. The strengthening mechanism was discussed.
RESUMEN
The influence of tempering temperature on the microstructure of 0.5Cr0.4W steels was investigated by scanning electron microscope, and the roles of grain boundary character, dislocation, and Taylor factor in sulfide stress cracking (SSC) resistance were interpreted using the election backscattered diffraction technique. The 0.5Cr0.4W steels tempered at 690 °C, 700 °C, and 715 °C all showed tempered martensites. The specimen tempered at 715 °C exhibited a higher critical stress intensity factor (KISSC) of 34.58 MPa·m0.5, but the yield strength of 800 MPa did not meet the criterion of 125 ksi (862 MPa) grade. When the specimen was tempered at 690 °C, the yield strength reached 960 MPa and the KISSC was only 21.36 MPa·m0.5, displaying poorer SSC resistance. The 0.5Cr0.4W steel tempered at 700 °C showed a good combination of yield strength (887 MPa) and SSC resistance (KISSC: 31.16 MPa·m0.5). When increasing the tempering temperature, the local average misorientation and Taylor factor of the 0.5Cr0.4W steels were decreased. The reduced dislocation density, and greater number of grains amenable to slippage, produced less hydrogen transport and a lower crack sensitivity. The SSC resistance was, thus, increased, owing to the minor damage to hydrogen aggregation. Therefore, 700 °C is a suitable tempering temperature for 0.5Cr0.4W casing steel.
RESUMEN
BACKGROUND: To compare the long-term therapeutic effects of stereotactic aspiration (SA), endoscopic evacuation (EE), and open craniotomy (OC) in the surgical treatment of spontaneous basal ganglia hemorrhage and explore the appropriate clinical indications for each technique. METHODS: Multiple-treatment inverse probability of treatment weighting (IPTW)-adjusted logistic regression analysis was performed to evaluate the therapeutic effects of these techniques. The primary and secondary outcomes were 6-month modified Rankin Scale (mRS) and mortality rates, respectively. RESULTS: A total of 703 patients were ultimately enrolled. For the entire cohort, the 6-month mortality rate was significantly higher (OR 2.396, 95% CI: 1.865-3.080), and the 6-month functional outcome was significantly worse (OR 1.359, 95% CI: 1.091-1.692) for SA than that of EE. The 6-month mortality rate for OC was significantly higher (OR 1.395, 95% CI: 1.059-1.837) than that of EE. Further subgroup analysis was stratified by initial hematoma volume and Glasgow Coma Scale (GCS) score. The mortality rate for SA was significantly higher for patients with hematoma volume of 20-40 mL (OR 6.226, 95% CI: 3.848-10.075), 40-80 mL (OR 2.121, 95% CI: 1.492-3.016), and ≥80 mL (OR 5.544, 95% CI: 3.315-9.269) than in the same subgroups of EE. The functional outcomes for SA were significantly worse than that of EE for hematoma volume subgroups of 40-80 mL (OR 1.424, 95% CI: 1.039-1.951) and ≥80 mL (OR 4.224, 95% CI: 1.655-10.776). The mortality rate for SA was significantly higher than that of EE for the GCS score subgroups of 6-8 (OR 2.082, 95% CI: 1.410-3.076) and 3-5 (OR 2.985, 95% CI: 1.904-4.678). The mortality rate for OC was significantly higher for the GCS score of 3-5 subgroup (OR 1.718, 95% CI: 1.115-2.648), and a tendency for a higher mortality rate of 6-8 subgroup (OR 1.442, 95% CI: 0.965-2.156) than that of EE. CONCLUSIONS: EE can decrease the 6-month mortality rate and improve the 6-month functional outcomes of spontaneous basal ganglia hemorrhage in patients with a hematoma volume ≥40 mL. EE can decrease the 6-month mortality rate of spontaneous basal ganglia hemorrhage in patients with a GCS score of 3-8.
