Arc welding

About: Arc welding is a research topic. Over the lifetime, 25393 publications have been published within this topic receiving 168182 citations.

Effect of current type on microstructure and corrosion resistance of super duplex stainless steel claddings produced by the gas tungsten arc welding process

Abstract: In this research, super duplex stainless steel filler metals were clad on high strength low alloy steel substrates by the tungsten arc welding process using pulsed and constant currents. To characterize the pulsed current effect, the phase composition and microstructure of the claddings were compared, and the corrosion behavior of the claddings was evaluated using cyclic polarization, electrochemical impedance spectroscopy and critical pitting temperature measurements. The results showed that the slower cooling rate of the constant current cladding led to a higher total reformed austenite content and better corrosion resistance. It was also found that the formation of thermally-activated secondary austenite did not influence the corrosion behavior significantly. The electrochemical impedance spectroscopy indicated that the passive film formed on the pulsed current cladding was more defective. The constant current cladding also showed ten degree higher critical pitting temperature than the one which was produced by pulsed current.

Electronic welding apparatus

Abstract: An electric welding apparatus which, for controlling at least one welding parameter, such as welding voltage or welding current, comprises a switching mode power supply (SMPS) as control element, the switching mode power supply preferably being regulated on the primary. The actual values of voltage and current are taken from the output of the switching mode power supply and fed to an analog control circuit. The set values of voltage and current are fed to a microprocessor via an entry keyboard, and in the microprocessor they are stored in a memory and passed on in analogous form to the analog control circuit which carries out a comparison of set value and actual value and, in dependence thereon, produces an error signal that is fed to a pulse width modulator of the switching mode power supply. The pulse width modulator is connected to the driver stages of the switching stages of the switching mode power supply, which switching stages are designed as boost regulator of buck regulator, and thus a pulse width modulation of the current pulses of the switching stages is effected in dependence on the difference between actual and nominal value. The converter section of the switching mode power supply preferably is designed as a modified single-ended buck regulator or as a push-pull full bridge, wherein it is operated at a fixed clock frequency of about 25 kHz. The secondary coil of the transformer of the switching mode power supply being either direct in connection with the output connection terminals of the switching mode power supply, or a secondary rectifier is connected between the secondary coil and the output connection terminals, whereby the secondary rectifier can be bridged by switch means.