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Investigation of Microstructures and Mechanical Properties of T92 Martensitic Steel/Super304 Austenitic Steel Weld Joints Made with Three Welding Consumables

Liang Z., Gui Y., Zhao Q.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1249--1256

EN

The microstructures and mechanical properties of T92 martensitic steel/Super304 austenitic steel weld joints with three welding consumables were investigated. Three types of welding materials ERNiCr-3, ERNiCrCoMo-1and T-304H were utilized to obtain dissimilar welds by using gas tungsten arc weld (GTAW). The results show that heat affect zone (HAZ) of T92 steel consists of coarse-grained and fine-grained tempered martensites. The microstructures of joints produced from ERNiCrCoMo-1 consist of equiaxed dendrite and columnar dendrite grains, which are more complicated than that of ERNiCr-3. In the tensile tests, joints constructed from ERNiCrCoMo-1 and T-304H met the ASME standard. The highest fracture energy was observed in specimens with the welding material ERNiCrCoMo-1. Ni content in weld seam of ERNiCrCoMo-1 was highest, which was above 40%. In conclusion, the nickel alloy ERNiCrCoMo-1 was the most suitable welding material for joints produced from T92 martensitic steel/Super304 austenitic steel.

2

Dynamic stability of a stepped drillstring conveying drilling fluid

Zhao G.-H., Tang S., Liang Z., Li J.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1409--1422

EN

Taking into account differences between a drill pipe (DP) and a drill collar (DC), the drillstring in a vertical well is modeled as a stepped pipe conveying a drilling fluid downwards to the bottom inside the string and then upwards to the ground from the annulus. An analytical model that describes lateral vibration of the drillstring and involves the drillstring gravity, weight on bit (WOB), hydrodynamic force and damping force of the drilling fluid is established. By analysis of complex frequencies, the influences of WOB, borehole diameter, DP length, velocity and density of the drilling fluid on the stability of the system are discussed.

3

Microseismic event denoising via adaptive directional vector median filters

Zheng J., Lu J.-R., Jiang T.-Q., Liang Z.

Acta Geophysica

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2017

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Vol. 65, no. 1

47--54

EN

We present a novel denoising scheme via Radon transform-based adaptive vector directional median filters named adaptive directional vector median filter (AD-VMF) to suppress noise for microseismic downhole dataset. AD-VMF contains three major steps for microseismic downhole data processing: (i) applying Radon transform on the microseismic data to obtain the parameters of the waves, (ii) performing S-transform to determine the parameters for filters, and (iii) applying the parameters for vector median filter (VMF) to denoise the data. The steps (i) and (ii) can realize the automatic direction detection. The proposed algorithm is tested with synthetic and field datasets that were recorded with a vertical array of receivers. The P-wave and S-wave direct arrivals are properly denoised for poor signal-to-noise ratio (SNR) records. In the simulation case, we also evaluate the performance with mean square error (MSE) in terms of signal-to-noise ratio (SNR). The result shows that the distortion of the proposed method is very low; the SNR is even less than dB.

4

Experimental study on the discharging characteristics of pulsed high-voltage discharge technology in oil plug removal

Bingnan Y., Jing Z., Liang Z., Chongxin L., Meng F.

Journal of Power Technologies

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2016

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Vol. 96, nr 4

261--268

EN

Oil plugging of the downhole during oilfield development leads to a decline in well yield. A new plug removal method based on pulsed high-voltage discharge technology was proposed in this paper to solve this plugging problem. A low-carbon steel high-pressure sealed drum was developed to simulate a downhole operating environment with high static pressure. Four sealed contact pins were designed on the drum cover. These pins were used to insert the high-voltage cable into the drum body while ensuring the drum is leakproof. The maximum static pressure borne by the drum was 40 MPa. An experimental system of pulsed high-voltage discharge was designed based on the drum. A platform for the discharging experiment was established according to the system principle diagram. The effects of variation in static pressure on discharging voltage, discharging current, critical breakdown field strength, discharging time and its data discretization, and other parameters were determined with water and crude oil as the discharging media. Experimental results indicate that increasing static pressure increases discharging time, enhances pulsed discharging randomness, reduces the strength of impact waves generated in the discharging media, and weakens the fracture-generating effect on the cement tube. Increasing the working voltage achieves better plug removal. However, the requirements for size, texture, and insulativity of plug removal equipment are elevated accordingly. This study provides a basis for the application of pulsed high-voltage discharge technology in oil reservoir plug removal.

5

Investigation on biomass performance of a submerged membrane bioreactor for treating soy sauce wastewater

Lv S., Liang Z., Li X., Fan H., Zen Y.

Environment Protection Engineering

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2016

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Vol. 42, nr 1

135--148

EN

A pilot study for investigating a membrane bioreactor (MBR) performance in treating soy sauce wastewater was divided into three stages. At stage 1, the MBR was operated without excess sludge withdrawal, and pollutants removal increased gradually and entered into a pseudo-stable phase eventually along with increasing mixed liquor suspended solid (MLSS). At stage 2, the growth of biomass and removal of pollutants were obviously decreased by lowering temperature. At stage 3, membrane permeate flux and sludge yield under various MLSSs were studied. Additional polishing steps including coagulation and oxidation were validated to be effective to ensure the treated wastewater to meet the discharge limits.

6

Research and fabrication of integrated optical chip of Mach-Zehnder microinterference accelerometer

Dong-Lin T., Bing D., Shan H., Kun-Qing X., Liang Z., Peng W.

Optica Applicata

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2012

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Vol. 42, nr 1

121-128

EN

A novel hybrid-integrated optical accelerometer, based on Mach-Zehnder interference, is described. The integrated Mach-Zehnder microinterferometer chip is investigated theoretically and experimentally. On the LiNbO3 substrate with the dimensions of 38 mm×6 mm×2 mm, MMI optical power splitter, Y-branching guide, phase modulator and polarizers are integrated to constitute the Mach-Zehnder microinterference chip. The performance of a prototype of the accelerometer is characterised. The measured frequency spectrum is in good agreement with the theoretical prediction.