Abstract
For long-serviced pressure equipment that is under severe working conditions such as a high temperature, high pressure, and corrosion, the material properties and structure will be unavoidably damaged or degraded, especially cracks and other damages at key positions such as welded joints, which seriously threaten the safe operation of the equipment. In order to promote the sustainable development of industries such as the chemical and petrochemical industries, remanufacturing technology has emerged worldwide, and various surface repair processes have also rapidly developed. As an important branch of surface repair technology, the high energy spark deposition (HESD) process is a new pulse cold welding repair technology developed from electro-spark deposition, which combines the advantages of multiple surface repair processes. The HESD process has the characteristics of a smaller heat affected zone and lower welding residual stress. It is a new type of repair method that is worthy of popularization and application. The process has been initially applied in the fields of surface modification and die steel repair. In this paper, the application of the HESD process to the repair of welded joints was introduced, the mechanical properties of the joints and the residual stress distribution after welding were analyzed, and the feasibility of HESD as a repair welding method for pressure structures was discussed. First, a numerical simulation of the temperature and stress field of HESD was proposed by using ABAQUS and the related subprograms, and the validity of the simulation results was verified by the residual stress test with the indentation strain method. Due to the precise control of the heat and pulse discharge working mode, the heat-affected zone and deformation caused by the HESD were extremely small, and the residual stress that was generated was low and only concentrated on the repair welding seam. Second, according to the numerical simulation and the test results of the mechanical properties of the welded joint, the optimal repair welding process parameters were obtained through the orthogonal experiment: peak current 45 A, pulse width 90 ms, and output voltage 10 V.
Highlights
In industrial production, numerous key parts of equipment are inevitably subjected to deformation, corrosion, fracture, wear, deterioration, and other damages under the long-term action of complex working conditions and the severe environment, such as the wear and scratch of rotor journals and turbine blades in service, hydrogen corrosion cracking of ethylene spherical tanks, etc
The feasibility of applying this technology to the repair of pressure structures was discussed from the viewpoint of the welding residual stress distribution, mechanical properties of the repair welding joint, etc
The optimal combination of repair welding process parameters was obtained via an orthogonal experiment
Summary
Numerous key parts of equipment are inevitably subjected to deformation, corrosion, fracture, wear, deterioration, and other damages under the long-term action of complex working conditions and the severe environment, such as the wear and scratch of rotor journals and turbine blades in service, hydrogen corrosion cracking of ethylene spherical tanks, etc. More than 80% of equipment failures are caused by surface wear, corrosion, and fatigue [1]. The traditional replacement or retirement method causes a Metals 2020, 10, 980; doi:10.3390/met10070980 www.mdpi.com/journal/metals. 2020, 10,to980 statistics, more than 80% of equipment failures are caused by surface wear, corrosion, and fatigue [1]. The traditional replacement or retirement method causes a waste of resources, which no longer conforms to the current industrial development trend. The remanufacturing technology has greatly saved the investment of enterprises and parts achieved achieved the maximum output, providing new methods for the treatment of damaged [2]. The maximum output,the providing methods for the treatment of damaged parts [2].surfacing welding. The remanufacturing technology has greatly saved the investment of enterprises and parts achieved achieved the maximum output, providing new methods for the treatment of damaged [2]. the maximum output,the providing methods for the treatment of damaged parts [2].surfacing welding
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