Ji Cai Feng

Research Status and Development Trend of Horizontal Welding Technology

The difficulties of horizontal welding technology are stated in this paper. On the basis of analyzing the defects occurred during horizontal welding technology as well as several corresponding methods are adopted nowadays. Control measures for horizontal welding technology high efficiency can be summed up to two types: weld pool quick solidification control measure and weld pool stable shape measure. The development history of their research and application is reviewed. And the mechanism of producing weld defects is deeply analyzed. The prospects and development of horizontal welding technology are elaborated.

Modeling and Analysis of Underwater Wet Weld Process Based on Regression Method

Underwater weld technology is urgently needed for the widely development of marine recourses, and weld automation technology is the inevitable choice because of the underwater environment. Because of the influence of the rigorous environment, the weld seam forming of underwater wet welding is very poor. To control the weld seam forming automatically, the model between the weld parameters and the weld seam shape must be built. This paper used arc sensor to monitor the electrical information of underwater wet welding process, and regression method was used to model the process, and the factors that influence the weld seam forming mostly were analyzed.

Research Status and Development Trend of Magnetically Controlled Welding Technology

The basic principle and the characteristics of magnetically controlled welding technology are introduced in this paper. The specific applications of domestic and foreign magnetically controlled welding technology in welding process are comprehensively analyzed at the moment, including the effect rule of external magnetic field on arc shape, metal droplet transfer, molten pool, weld microstructure, mechanical properties. And the key problems needing to be solved are deeply investigated. The developments of magnetically controlled welding technology in the future are also forecasted.

Microstructure and Mechanical Property of the ZrB2-Based Ultra-High-Temperature Ceramic Composites Brazed Joint

ZrB2-SiC ceramic composites was brazed by using Ti-Zr-Ni-Cu active filler in a vacuum furnace. The microstructure and interfacial phenomena of the joints were analyzed by means of SEM, EDS and XRD. The joining effect was evaluated by shear strength. The results showed that the reaction products of the ZrB2-SiC ceramic composites joint brazed with Ti-Zr-Ni-Cu active filler were TiC, ZrC, Ti5Si3, Zr2Si, Zr(s,s) and (Ti, Zr)2 (Ni, Cu). The maximum shear strength of the ZrB2-based ultra-high-temperature ceramic composites brazed joints is 143.5 Subscript textMPa at brazing temperature T=920°C and holding time t=10min.

Research Status and Development Trend of Narrow-Gap TIG Welding

This paper reviews the research of narrow-gap TIG welding. It contains narrow-gap welding with double arcs, narrow-gap welding with double wires, compounded narrow-gap welding, TIG welding under controlled magnetic arc and ultra-narrow-gap welding. It analyzes the merits and drawbacks of every manner in narrow-gap welding. Considering the little groove angle and small gap, how to make sure sidewall fusion, the improvement of fusion welding forming and the prevention of weld crack are focal points of narrow-gap welding researches. The further development of electrical and visual sensors can lower the precision of work piece assembling and solve the central location problem of electrode. Narrow-gap welding will have a good application foreground.

Interfacial Reaction of Alumina Ceramics to Mild Steel Braze Joint

Al2O3 is brazed with mild steel using 70Ag-27Cu-3Ti (wt.%) active filler alloy at 900°C for 5 min. The interfacial reaction products are analyzed with X-ray diffraction (XRD)．The interfacial phases are analyzed with EDAX. According to the experimental observations, the interfaces developed during brazing have been systematically characterized and the structure are separately Ti3Cu3O/Ti3Al+ TiMn+TiFe2 +Ag(s,s)+Cu(s,s)/TiC from alumina ceramics side to mild steel side.

Experimental Study of Electron Beam Welded QCr0.8 Bronze Joint

The butt welding test has been performed on QCr0.8 bronze by electron beam welding. Microstructure of the joint was examined by optical microscopy and scanning electron microscopy with EDS. Microhardness of the joint was determined to evaluate the mechanical property of the joint. The fusion zone and the heat affected zone became the weak area of the joint due to the growth of grains and the redissolve of strengthening phase. The decrease of strengthening phase has a major influence on the microhardness reduction of the joint..

Investigation of Compressive Damage Mechanisms in 3D Braided Composites by the Acoustic Emission Events Energy and Amplitude

The deformation behavior and damage mechanism of 3-D carbon/epoxy braided composites with different braiding angles under the monotonic compressive loading are investigated by the acoustic emission (AE) technique. The damage process is divided into several different regions based on the change of the accumulative AE event counts. Correlations between the damage mechanisms and the AE results are established in terms of the events energy and amplitude. These correlations can be used to monitor the fracture growth process in the braided composites. Experimental results reveal that the AE technique is an effective tool for identifying damage mechanisms.

Analysis of Underwater Wet Welding Seam Forming Based on Arc Sensor Information

It is difficult to obtain fine weld seam of underwater welding because of the water environment, this paper used arc sensor to obtain electrical information of the under water wet welding process, and BP neural network was used to model the process, experiment results showed the model could predict the process precisely, this laid the foundation for further controlling the welding quality automatically.

Underwater Wet Weld Seam Tracking Based on Passive Visual Sensor

Weld seam tracking system is urgently needed in weld automation process, but it has not been well studied in underwater weld applications. This paper used visual sensor to automatically monitor the weld seam in underwater wet weld process, and image processing algorithms were developed to remove the influence of water environment on the captured image and automatically obtain the weld torch deviation, and the weld torch was adjusted automatically according to the deviation obtained by the image, experiment results showed that the system could meet the requirements of underwater wet welding process.