Significant Increase In Penetration Depth Research Articles

Activated flux TIG welding of stainless steel pipes

In this work, the presence of TiO2 nanoparticle-based activated flux combined with orbital welding of seamless thick-walled pipes of stainless steel and lowcycle pulse current was done, representing a novel combination of welding processes parameters. Control specimens were welded without flux and consumable material, and without flux with the consumable material. Experimental welding with different welding parameters was done. Special attention was given to characterize the flux by zetasizer method, representing a new approach, versus the conventional approach where the nominal oxide particle size is reported. The obtained welds were visually tested, macroanalyzed, their microstructures examined, and their tensile and bending properties determined. The results show that the flux influences a significant increase in penetration depth, up to full penetration, which has a positive effect on the increase in the tensile and bending properties of the weld metal. Material behavior model was developed, based on microstructural features of the near weld-line. Without the flux, grain enlargement occurred near the surface, while with flux, it occurred under the weld, which can be attributed to recrystallization and a reversed Marangoni convection.

Performance of activated TIG welding in 304 austenitic stainless steel welds

Six different types of oxides Cr2O3, FeO, Fe2O3, MoO3, SiO2, and Al2O3 were used to investigate the effect of oxide flux on weld morphology, microstructure and mechanical properties in 304 austenitic stainless steel welded joints. An autogenous TIG welding was used to join 8mm thick austenitic stainless steel plate and a thin layer of oxide was applied prior to welding. The results indicated that there was a significant increase in penetration depth on using metal oxides but Al2O3 does not give satisfactory result. The microstructures were found to be different on using different oxides. The mechanical properties of the weld were almost similar to that of parent metal.

Evaluating the Effect of Micropump© Position, Internal Pressure and Doxorubicin Dosage on Efficacy of Pressurized Intra-peritoneal Aerosol Chemotherapy (PIPAC) in an Ex Vivo Model.

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a novel clinical approach to the treatment of peritoneal carcinomatosis. A well-established, not anatomic ex vivo PIPAC model was used to investigate the influence of changes in internal pressure, distance of the Micropump(©) (MIP) to the distributing surface and the drug concentration on the penetration depth of doxorubicin in the target tissue. Doxorubicin was aerosolized in an ex vivo PIPAC model using a hermetic container system mimicking the abdominal cavity. Fresh post-mortem swine peritoneum was cut into proportional samples. Tissue specimens were spatially placed at 4 different spots within the box: P1, on the distributing surface of the box, directly opposite to MIP; P2, on the side wall of the box; P3, on the ceiling of the box; P4, on the distributing surface with a partial cover. Impact of changes in the following parameters were analyzed and compared with clinically established values (CEVs) at our center: pressure (CEV=12 mmHg), distance of the MIP from the distributing surface (CEV=8 cm) and doxorubicin concentration (CEV=3 mg/50 ml). In-tissue doxorubicin penetration depth was measured using fluorescence microscopy on frozen thin sections. Tissue positioning in the box had a significant impact on drug penetration after PIPAC with CEV. Under CEV conditions, the highest drug penetration depth was observed in the tissue placed on the distributing surface directly opposite to the MIP (P1: 351 μm, P2: 77 μm, P3: 66 μm, P4: 34 μm). A closer positioning of the MIP lead to a significantly higher mean depth penetration of doxorubicin in the P1 in contrast to other samples in which a reduced drug penetration was observed (1 cm vs. 8 cm distance from MIP to the distributing surface, P1 at 1 cm: 469 μm vs. P1 at 8 cm: 351 μm, p<0.0001; P2 at 1 cm: 25 μm vs. P2 at 8 cm: 77 μm, p<0.0001; P3 at 1 cm: 21 μm vs. P3 at 8 cm: 66 μm, p<0.001; P4 at 1 cm: 13 μm vs. P4 at 8 cm: 39 μm, p=0.021). Higher doxorubicin concentrations led to a highly significant increase of drug penetration in P1 (1 cm vs. 8 cm, p<0.0001), but only a little significant increase in other samples. An increase of internal pressure did not show a significant increase in penetration depth of doxorubicin. Our ex vivo data suggest that a higher pressure does not increase the penetration deepness of doxorubicin. Higher drug dosage and a closer positioning of the MIP toward the target lead to a higher penetration of doxorubicin within the samples. A more homogeneous penetration within all targets cannot be achieved by changing drug concentration, position of the nozzle or pressure increase.

Reduced pressure laser welding of thick section structural steel

This study investigates the influence of joint edge surface edge roughness and pre-set air gap on the weld quality and penetration depth in partial vacuum atmospheric conditions laser beam welding. High-power autogenous disk laser keyhole welding of low alloyed steel SM400A was carried out with butt joint configuration with 16kW laser power and 1m/min welding speed in partial vacuum atmospheric conditions. Geometry, quality of the welds was investigated. The results indicate that a significant increase in penetration depth can be achieved with constant heat input without loss of weld quality.