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The Study on the Characteristics of Molten Pool and Temperature Field during Laser Full Penetration Welding of 304 Stainless Steel

Author: ChenJunJie
Tutor: YuYouSheng；DuanAiQin
School: Wuhan University of Technology
Course: Materials Processing Engineering
Keywords: Laser full penetration welding 304 stainless steel Molten pool Temperature field
CLC: TG402
Type: Master's thesis
Year: 2010
Downloads: 247
Quote: 0
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Abstract

Laser welding technology as a new materials processing technology, compared with the traditional method of welding with high energy density welding speed, weld depth and width than the big advantages of the heat affected zone is narrow and small deformation of the weldment. In recent years, due to the rapid development of high-power lasers, laser welding to become important in the field of modern industrial manufacturing processing means, and has vast potential for development. Between the laser welding process, the molten pool characteristics and the temperature field and welding process parameters and weld quality are intrinsically linked. Therefore this paper test and calculation method of combining the characteristic quantities of the molten pool under different laser welding conditions and the change of the temperature field, which not only increases the understanding of the relationship between the molten pool and the welding parameters and welding results, but also achieved with a relatively simple and applicable to laser weld pool temperature field model can forecast actual welding. Deep penetration laser weld pool and the temperature field of the main characteristics of the mathematical model, combined with the research objectives of this article, select Rosenthal moving line heat source as the heat source model, and at the same time, of Rosenthal mobile line heat source model for laser full penetration penetration welding limitations analysis, and based on the way to the introduction of the equivalent parameters of the laser full penetration weld pool temperature field and the characteristic value calculation results and actual results closer to the analytical solution of the moving line heat source and use as laser full penetration weld pool and the prediction of the temperature field model. The first test, 304 stainless steel CO2 laser welding process and results for different welding conditions analyzed, the results show that the welding heat input and weld shaping their organizations closely related. While taking advantage of the high-speed camera for the molten pool the positive measurement result of the back of the characteristics of based on Rosenthal mobile line heat source model being back equivalent coefficient to determine, based on the establishment of the molten bath temperature field prediction model. The results show that the line energy in a certain range, the predicted and measured results are in good agreement, but the line is too large or too small, the equivalent coefficient to be amended accordingly. This is mainly due to the penetration welding in different penetration state the orifice characteristic changes lead to the energy absorbed by the weldment changes caused. Above the molten pool and the temperature field prediction model on the corresponding line energy center of the weld heat cycle is calculated, and the results showed that: the line greater the energy, the point on the melting point at a cooling rate of the smaller, at 800 ° C -500 ℃ (t8 / 5) The longer the cooling time, which is also very good to explain why the line the greater the energy, the the weld grain will become coarse. Further studies of laser power and welding speed, plate thickness, the protection of the impact of the gas on penetration welding pool temperature field, and the molten pool and predictive model of the temperature field in different welding conditions applicable and appropriate welding conditions model equivalent to the variation of the parameters, and then use the appropriate welding conditions, the prediction model to calculate the center of the heat cycle of the weld. YAG laser full penetration welded 304 stainless steel, molten pool and the temperature field in a different line energy prediction model, the corresponding line energy forecasting model to calculate the thermal cycle of the weld center point, and the line energy The analysis of the relationship between the characteristics of the molten pool and the temperature field, the weld thermal cycling center point and the final weld shape and weld prediction with the experimental results can be found in line. In the same welding parameters, compare the CO2 laser and YAG laser welding results, the molten pool characteristics and temperature field prediction model and found that the two types of laser heat source due to the different effects of metal vapor and plasma, weld formation characteristics, the molten pool characteristics and prediction of the model parameters have very different, and should therefore be as two heat source process modeling.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding general issues > Welding heat transfer process
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