Investigation of Ultrasonic Testing Failure in ERW Line Pipe of API 5L X52M Grade

Electric resistance welding (ERW) is conventional manufacturing technology for production of linepipe. ERW is known for its low cost, high efficiency & reliability. Investigation was performed on Electric Resistance Welded (ERW) pipes having Ultrasonic Test (UT) indication observed during in-process inspection. The location of indication was adjacent to weld fusion line. The study was done on pipe size 168 mm (6.6 inch) outside diameter and 6.4 mm wall thickness of API 5L X52M grade to verify the cause of UT failure related to pipe manufacturing process and/or steel making process. The samples were drawn from UT indicated area and analysis is carried out by chemical testing, optical microscopy and scanning electron microscopy with energy dispersive spectroscopy. From systematical research by Why-Why analysis, it is clear that the reason of sub-surface defects on ERW pipe is due to presence of non-metallic inclusions. On the basis of the composition of observed non metallic inclusion, possible sources are identified. The countermeasures for each source cause were verified and successfully implemented the affected one.

Characterization of a PCB Based Pressure Sensor and Its Joining Methods for the Metal Membrane

Essential quality features of pressure sensors are, among other accuracy-related factors, measurement range, operating temperature, and long-term stability. In this work, these features are optimized for a capacitive pressure sensor with a measurement range of 10 bars. The sensor consists of a metal membrane, which is connected to a PCB and a digital capacitive readout. To optimize the performance, different methods for the joining process are studied. Transient liquid phase bonding (TLP bonding), reactive joining, silver sintering, and electric resistance welding are compared by measurements of the characteristic curves and long-term measurements at maximum pressure. A scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) analysis was used to examine the quality of the joints. The evaluation of the characteristic curves shows the smallest measurement errors for TLP bonding and sintering. For welding and sintering, no statistically significant long-term drift was measured. In terms of equipment costs, reactive joining and sintering are most favorable. With low material costs and short process times, electric resistance welding offers ideal conditions for mass production.

Using Taguchi Grey Relational Analysis Multi-Object of Process Parameters in Electric Resistance Welding of Wire to Recovery AISI1045 Steell Shaft

This study focuses on the multi-objective optimization of the welding joint of AISI 1045 steel shafts with AISI 1070 filler wire 1.8 mm in diameter by electric resistance welding method. During the welding process, welding parameters input are important because it determines the quality of the welding joint. Therefore, in this study, Taguchi method was used in combination with grey relational analysis to select the welding parameters suitable for this welding process. The experiments were performed according to the orthogonal array L9 designed by the Taguchi method. The input welding mode parameters used in this study include welding current (Ih), force (F), welding speed (Vh). The output characteristics for the selected weld quality target are minimum tensile strength and micro hardness. Grey analyzes were conducted to optimize for the input parameters, the analysis results show that the set of input parameters suitable for the output quality are Ih = 7.5 KA; F = 1.7 KN; Vh = 1.5 cm/s. This is followed by the process of assessing the significance of the factors to all qualities of the welded joint using the ANOVA analysis process.

Research Status and Progress of Welding Technologies for Molybdenum and Molybdenum Alloys

Owing to its potential application prospect in novel accident tolerant fuel, molybdenum alloys and their welding technologies have gained great importance in recent years. The challenges of welding molybdenum alloys come from two aspects: one is related to its powder metallurgy manufacturing process, and the other is its inherent characteristics of refractory metal. The welding of powder metallurgy materials has been associated with issues such as porosity, contamination, and inclusions, at levels which tend to degrade the service performances of a welded joint. Refractory metals usually present poor weldability due to embrittlement of the fusion zone as a result of impurities segregation and the grain coarsening in the heat-affected zone. A critical review of the current state of the art of welding Mo alloys components is presented. The advantages and disadvantages of the various methods, i.e., electron-beam welding (EBW), tungsten-arc inert gas (TIG) welding, laser welding (LW), electric resistance welding (ERW), and brazing and friction welding (FW) in joining Mo and Mo alloys, are discussed with a view to imagine future directions. This review suggests that more attention should be paid to high energy density laser welding and the mechanism and technology of welding Mo alloys under hyperbaric environment.

Theoretical Analysis of Five-Point Bending and Springback for Preforming Process of ERW Pipe FFX Forming

Flexible forming excellent (FFX) forming of electric resistance welding (ERW) pipe is an advanced roll forming method. In order to understand FFX forming mechanism and set reasonable roll parameters, five-point bending process and springback process for preforming section of ERW pipe FFX forming are analyzed. Under various assumptions, the bending process of sheet metal is divided into full elastic bending stage and elastic-plastic bending stage by analyzing the forming law and simplifying the contact state model of roll bending process. Based on the theory of plane bending theory, the five-point bending springback model is established. Mathematical expressions of bending curvature and rotation angle of arbitrary particle on plate under arbitrary state are derived. The curvature calculation formulas of each particle on plate after springback are obtained, and then the calculation formulas of bending angle and rebound angle after springback are obtained. The theoretical analysis results are verified by the wide plate five-point bending experiment. The theoretical value of springback angle agrees well with the experimental results. The maximum deviation of springback angle is 0.42 degrees. The results show that the five-point bending model is reasonable. It provides theoretical support for the preforming model of flexible roll forming.