Papers by Keyword: Dilution

Abstract: Leachate treatment is a critical component of municipal solid waste management due to the complex and variable nature of leachate composition. This study investigates a dilution-based strategy to address insufficient leachate volume during a mandated 21-day reliability test at the Kelaniya Transfer Station leachate treatment plant, part of the Metro Colombo Solid Waste Management Project. The primary objective was to evaluate the plant's capacity to treat leachate under continuous operational conditions at its design flow rate of 160 m³/day, despite a limited leachate supply caused by non-functional compactors. A dilution ratio of 50–60% was applied to available leachate to meet volume requirements, with the underlying assumption that such dilution would not significantly alter leachate variability. Baseline and incoming leachate samples were analyzed for key parameters, chemical oxygen demand (COD), ammonia nitrogen (NH₄–N), total nitrogen (TN), and total suspended solids (TSS). Statistical tests, including two-sample t-tests and Levene’s tests, were conducted to assess variability before and after dilution. The results revealed significant variation between undiluted samples from the same source, confirming the inherent variability of leachate. However, Levene’s tests showed no statistically significant differences in variance for NH₄–N, TN and TSS before and after dilution, indicating that the dilution process preserved the natural variability of leachate characteristics. The findings support the use of controlled dilution as a valid strategy for leachate volume supplementation during performance testing, without compromising the reliability of treatment plant assessment. Nevertheless, dilution reduces nutrient loading, particularly carbon input, and may not reflect peak loading scenarios. To address this, a supplementary a separate testing phase was conducted using undiluted leachate with high-strength characteristics over a period, specifically to evaluate the treatment plant’s capacity to handle peak loading scenarios.

Abstract: This paper presents an experimental study on various input parameters to optimize the dilution percentage of stainless steel 409L plates by using metal inert gas welding (MIG). Dilution represents the proportion of base material melted to the entire cross-sectional area of the fusion zone. A mathematical equation was generated using the design matrix to obtain an optimized parametric combination of input parameters. Further, the adequacy and the significance of the generated equation were verified using F-test & T-test, respectively. In the graphical analysis performed using response surface methodology (RSM) it was inferred “Wire feed rate”, “welding speed” and “voltage” came out to as input parameter which showed a profound effect on dilution. The results show that the proposed method, mathematically agrees well with the definition of weld dilution. It was inferred increasing dilution to a level higher than the critical value; the weld can be concentrated as well when the filler wire is rich in the same composition as the substrate does.

Abstract: Hard-facing is one of processes for repairing metallic surface of equipment or parts of machinery that are lost due to outworn mechanism. Therefore, hard-facing requires suitable variables to obtain the hardest hard-faced metals. This research aimed to study influence of welding speed on hard-facing affecting microstructure and hardness of the hard-faced metals on JIS-S45C carbon steel with MIG welding. According to the experiment, hard-facing with welding speed at 250 mm/min contained dilution of elements lower than welding speed at 200 and 300 mm/min. Therefore, the hard-faced metals contained elements the most including Silicon 2.25 %, Chromium 6.12 % and Manganese 0.51 %, which affected the enhancement of mechanical properties of welded metals. The hard-faced metal had highest average hardness at 705.9 HV0.1.

Abstract: The success of Dissimilar Metal Welding (DMW) occurred in optimal Heat-input (HI) parameters. The quality of welding joints was affected by dilution, hardness value, and intermetallic microstructure. DMW quality research was carried out on stainless steel SA SS312-TP304 and SA 53GrB carbon steel using the GTAW (Gas Tungsten Arc Welding) process with Heat-input of 1866.6 to 2362.2 J/mm. Visual observation on weld joints was not found weld defects. The optimal dilution area in the Schaeffler Diagram was obtained 35.35% austenitic area and without ferrite content. The lowest hardness value on carbon steel was 145 HV. The highest hardness value of 197 HV occurred in filler-metal dilution on carbon steel, so the difference in the value of hardness was high. The hardness value on stainless steel was 184 HV and in filler-metal stainless steel dilution was 172– 90 HV, so the difference in hardness value was low. Microstructure filler-metal dilution on stainless steel was austenite-dendritic, filler-metal dilution on carbon steel was fine-grained dendritic, and on allweld metal coarse-grained dendritic metal. HAZ stainless steel austenite microstructure and ferrite-pearlite carbon steel with an indication of a ferrite net. Observation of dilution, hardness value, and microstructure in DMW did not have a significant effect. This welded joint could be used as a reference in the DMW fabrication process for stainless steel and carbon steel pipe connections.

Abstract: This work studies the surface welding parameters for a practical repair for pearlitic rail grades: R260 and R350HT. A filler metal containing low carbon (0.15 %), high silicon (0.5 %) and nickel (2.5 %), self-shielded flux-core welding electrode (FCAW-S) is the candidate in order to ensure the preferable carbide-free bainite. The film-like morphology of the retained austenite is reported to promote the wear resistance and is ensured by silicon and nickel. The effect of preheat temperature and dilution on the microstructure and resulting hardness can be concluded. Too high dilution, as a result of high current and travel speed, and the reheating during the welding of the second layer can result in martensite formation and too high hardness. Proper control of the dilution ensures satisfactorily hardness and avoids martensite formation.

Abstract: Dissimilar metal welding (DMW) is frequently used to join stainless steels to other metals in Thermal Power Plants (TPP) and industries. DMW process has been shown to have great advantages for many years. This approach is most often used where a transition in mechanical properties and/or performance in service are required. The objective of this research is to review the basic principles of fusion welding of dissimilar metals.In experiments, the two seamless pipes with 18 mm thick, one modified SS 304L austenitic stainless steel was welded to another modified carbon steel A 106B by means of shielded metal arc (SMAW) and gas tungsten arc (GTAW) welding processes using ER309L and E 309L-16 type of filler metal. Before welding, essential variables were analysed so that creating preliminary welding procedure specifications (pWPS). After welding, weldment was tested by NDT such as visual, penetrant and radiography. Microstructural examinations were carried out including macro and micrographs, grain size analysis, and hardness measurements. Transverse tensile, and face/ root bend testing were carried out. Finally, WPS was established conformance to standards of TPP structure toward to building Nuclear Power Plant in Vietnam.

Abstract: The quality and geometry of deposited bead depend on their input process parameters and their interaction effects in fusion welding process. Minimum dilution and maximum bead size are the most desirable property in material processing applications. The effects of process parameters on dilution and bead geometry have been analysed during material deposition by Plasma Transferred Arc Welding (PTAW) process using the response surface method. The experimental data are used for modelling using three level factorial techniques. The mathematical models have been developed for bead height, width and dilution. The accuracy of the models has been checked using the analysis of variance. The effects of process parameters on bead geometry and dilution have been investigated.

Abstract: Stellite 6 was fabricated by laser cladding on a 1050 steel (MS) substrate with laser powers of 1 kW (MS-1) and 1.8 kW (MS-1.8). The chemical compositions and microstructures of the coatings were analysed by X-Ray Fluoroscense, optical microscopy and scanning electron microscopy. The microhardness of the coatings was examined and the wear mechanism of the coatings was evaluated using a ball-on-plate wear testing machine. The results indicated less cracking and pore development for Stellite 6 coatings applied to the 1050 steel substrate with the lower laser power (MS-1). Moreover, the Stellite coating for MS-1 was significantly harder than that obtained for MS-1.8. The wear test results showed that the weight loss for MS-1 was much lower than for MS-1.8. The evaluations of dilution and calculation of carbon content indicated that MS-1 has lower dilution and higher coating C content than MS-1.8. It is concluded that the lower hardness of the coating for MS-1.8, substantially reduced the wear resistance of the Stellite 6 coating and the lower hardness of the coating for MS-1.8 was due to higher level of dilution and lower coating C content. The coating-substrate couple must be considered in assessing the likely performance of the coating under service conditions.

Abstract: Welding input process parameters are playing a very significant role in determining the weld bead quality. The quality of the joint can be defined in terms of properties such as weld bead geometry, mechanical properties and distortion. Experiments were conducted to develop models, using a three factor, five level factorial design for 304 stainless steel as base plate with ER 308L filler wire of 1.6 mm diameter. The purpose of this study is to develop the mathematical model and compare the observed output values with predicted output values. Welding current, welding speed and nozzle to plate distance were chosen as input parameters, while depth of penetration, weld bead width, reinforcement and dilution as output parameters. The models developed have been checked for their adequacy. Confirmation experiments were also conducted and the results show that the models developed can predict the bead geometries and dilution with reasonable accuracy. The direct and interaction effect of the process parameters on bead geometry are presented in graphical form.

Abstract:

The present paper explores the impact of laser cladding parameters on the corrosion behavior of the resulting surface. Powders of Inconel 625 and austenitic Metco 41C steel were deposited on steel substrate. It was confirmed that the level of dilution has profound impact on the corrosion resistance and that dilution has to be minimized. However, the chemical composition of the cladding is altered even in the course of the cladding process, a fact which is related to the increase in the substrate temperature. The cladding process was optimized to achieve maximum corrosion resistance. The results were verified and validated using microscopic observation, chemical analysis and corrosion testing.