| TCS stainless steel for railway wagon is a kind of economic corrosion-resistant material, which has enough obdurability and is more excellent on corrosion-resistant than ordinary high strength weathering steel. Therefore, the study on welding technics of TCS stainless steel has great significance on theoretics and practice.When welding TCS stainless steel, the ferrite grain in CGHAZ will grow up easily, this will decrease the toughness of welding joint. Therefore, in the paper, in order to improve the fatigue resistance of welding joint, the toughness of in low temperature(-40℃) is set as the main object of the study work carried out by experiment to research the relationship between the welding technical parameters of pulse GMAW and the toughness.In the paper, the influencing factors such as welding speed,the pulsed current, time and frequency on the toughness are discussed by orthogonal experiments. Through orthogonal experiment and regression analysis, the mathematical models are respectively found to describe the influence of welding technical parameters on the toughness of nominal fusion-line and weld center line.The welding technical parameters and their interactions of pulse GMAW which affect the toughness of welding joint are analyzed on the base of the mathematical models. And then, the optimum welding technical parameters for the higher toughness were optimized by the optimizing function in MATLAB, that is, pulse current 450A,pulse time 2.3ms,pulse frequency 250Hz,and welding speed 500mm/min,when it is proved that the highest toughness of the nominal fusion-line can be achieved.Furthermore, we can found that the weld zone is composed of austenite and ferrite, and the CGHAZ is composed of ferrite and lath martensite by metallographic analysis and XRD analysis. When double-layer-welding, the microstructure of weld is good for the toughness of weld. Besides, the grain size, the width of CGHAZ, the modality and proportion of martensite all have affection on the toughness.
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