In order to reduce sulphur （ S ） and phosphorus （ P ） impurities in deposited metal, a small amount of rare earth （RE） lanthanum （ La） and yttrium （Y） were added into the coating ofE4303 electrode, a low carbon steel electrode. The microstructures of deposited metal were analyzed with metalloscope, and then the content of S and P was examined by energy dispenive X-ray spectrometer （ EDXS ）, and by wavelength dispersive X-ray fluorescence （XRF） spectrometer for further examination. The results show that the proper addition of La and Y can be beneficial to the desulfurization and dephosphorization of the deposited metal. Certainly, difference in the addition amount of La and Y could lead to various desulfurization and dephosphorization efficiency, in which the former is more obvious than the latter. With the proper amount of La attd Y, there is finer microstructure in deposited metal, and mechanical properties are improved as well. The S content in deposited metal with added La and Y decreases by 44. 44 wt. % , while the P content 6. 67 wt. %, compared with that in deposited metal without La and II.
In order to improve the mechanical properties of deposited metal of ilmenite type welding electrode, CeO2/La rare earth elements were added into electrodes based on E4301 electrode, then electrodes were produced, test plates were welded, and mechanical properties were tested based on National Standards of China. For the sake of solving the problems of large amount of mechanical properties tests, long test cycle and high test cost during the conventional production process of electrode, a prediction model of the mechanical properties of deposited metal based on Takagi-Sugeno （T-S） fuzzy neural network was established. Mn, Si and C contents of medium manganese in electrode, CeO2, and La contents of electrode and welding speed were selected as input variables of the prediction model, and the tensile strength, lower yield strength, elongation, impact energy and hardness of de- posited metal were selected as output variables. Finally, predicting experiment was done under test samples, and results show that average relative prediction error of the tensile strength, lower yield strength, elongation and hardness are 0.91%, 2.57 %, 4.94 % and 1.94 %, respec- tively, which reach the need of actual production. The re- sults of prediction show that the mechanical properties of deposited metal of electrode containing rare earth can be forecasted accurately through material composition of electrode and welding parameters based on T-S fuzzy neural network model.
The ilmenite welding electrode has advantages of low cost and excellent welding technological properties.However, the welding quality is affected adversely by its poor crack resistance.To solve this problem, 12 kinds of rare earths coating formulas were optimized by means of orthogonal test design and curve fitting.Then the powders containing La/Ce O2 were extruded into ilmenite welding electrode through screw-type pressing–scribbling machine.After that, a series of mechanical properties tests were conducted according to national standards.Next, the mechanical properties data were analyzed comprehensively by analyzing variance, boxplot as well as Minitab 3D surface chart.The results show that compared with the formula without rare earth, the deposited metal’s impact toughness,the lower yield strength, the tensile strength, and the hardness are increased by 54.44 %, 9.25 %, 6.37 %, and4.27 %, respectively.In other words, Electrode 6 with the La/Ce O2 amount of 0.5 %/0.1 % in coating has better mechanical properties.
