The present study is concerned with the effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on tensile and impact properties of the ferritic stainless steel ...The present study is concerned with the effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the joints fabricated by austenitic stainless steel, ferritic stainless steel and duplex stainless steel filler metals were evaluated and the results were reported. From this investigation, it is found that the joints fabricated by duplex stainless steel filler metal showed higher tensile strength and hardness compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Joints fabricated by austenitic stainless steel filler metal exhibited higher ductility and impact toughness compared with the joints fabricated by ferritic stainless steel and duplex stainless steel filler metals.展开更多
The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied. Rolled plates of 4 mm thickness have been used as the base material...The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied. Rolled plates of 4 mm thickness have been used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure, and fracture surface morphology of continuous current gas tungsten arc welding （CCGTAW）, pulsed current gas tungsten arc welding （PCGTAW）, and plasma arc welding （PAW） joints are evaluated and the results are compared. It is found that the PAW joints of ferritic stainless steel show superior tensile and impact properties when compared with CCG-TAW and PCGTAW joints, and this is mainly due to lower heat input, finer fusion zone grain diameter, and higher fusion zone hardness.展开更多
Based on the theory of hydrogen enhanced localized plasticity of the hydrogen induced cracking and the consideration of the effect of the residual stress produced by eliminated stress heat-treatment, a fractal model o...Based on the theory of hydrogen enhanced localized plasticity of the hydrogen induced cracking and the consideration of the effect of the residual stress produced by eliminated stress heat-treatment, a fractal model of hydrogen induced cracking was presented, and the relationships among the effective surface energy (H), fractal dimension D and stress intensity factor of hydrogen induced cracking, KIH, for welding pipeline under hydrogen environment was set up, from which the relationship of D and KISCC was obtained. The model has been verified experimentally to be correct.展开更多
The effects of alloying elements in welding wires and submerged arc welding process on the microstructures and low-temperature impact toughness of weld metals have been investigated. The results indicate that the opti...The effects of alloying elements in welding wires and submerged arc welding process on the microstructures and low-temperature impact toughness of weld metals have been investigated. The results indicate that the optimal contents of alloying elements in welding wires can improve the low-temperature impact toughness of weld metals because the proeutectoid ferrite and bainite formations can be suppressed, and the fraction of acicular ferrite increases. However, the contents of alloying elements need to vary along with the welding heat input. With the increase in welding heat input, the contents of alloying elements in welding wires need to be increased accordingly. The microstructures mainly consisting of acicular ferrite can be obtained in weld metals after four-wire submerged arc welding using the wires with a low carbon content and appropriate contents of Mn, Mo, Ti-B, Cu, Ni, and RE, resulting in the high low-temperature impact toughness of weld metals.展开更多
The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is ...The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigatio.n, it is found that gas tungsten arc welded joints of ferritic stainless steel have superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.展开更多
The formation mechanism of inclusion in welds with different aluminum contents was determined based on thermodynamic equilibrium in self-shielded flux cored arc welds.Inclusions in welds were systematically studied by...The formation mechanism of inclusion in welds with different aluminum contents was determined based on thermodynamic equilibrium in self-shielded flux cored arc welds.Inclusions in welds were systematically studied by optical microscopy,scanning microscopy and image analyzer.The results show that the average size and the contamination rate of inclusions in low-aluminum weld are lower than those in high-aluminum weld.Highly faceted AlN inclusions with big size in the high-aluminum weld are more than those in low-aluminum weld.As a result,the low temperature impact toughness of low-aluminum weld is higher than that of high-aluminum weld.Finally,the thermodynamic analysis indicates that thermodynamic result agrees with the experimental data.展开更多
An experimental setup to excite ultrasonic by modulating electrical arc was applied in the submerged arc welding （SAW） process of 09 MnNiDR steel to study its effect on quality of the welds. Arc-excited ultrasonic e...An experimental setup to excite ultrasonic by modulating electrical arc was applied in the submerged arc welding （SAW） process of 09 MnNiDR steel to study its effect on quality of the welds. Arc-excited ultrasonic energy refines grains of the welds and more acicular ferrite （ AF） appears in the fusion zone. It also enhances impact toughness of the joints at -70 ℃ significantly. With the ultrasonic of 50 kHz, the toughness is improved by 47% in the fusion zone and by 82% in the heataffected zone （HAZ）. The fractography of welds shows that the fracture is changed from cleavage fracture to gliding fracture while applying ultrasonic vibration.展开更多
Welded joint impact performances of low-alloy carbon steel plates welded by full-automatic gas metal arc welding （GMAW） were evaluated. To clarity the effect of impact temperature on impact properties of weld metal ...Welded joint impact performances of low-alloy carbon steel plates welded by full-automatic gas metal arc welding （GMAW） were evaluated. To clarity the effect of impact temperature on impact properties of weld metal （WM） and heat- affected zone （ HAZ）, Charpy V impact tests at different temperatures and fracture surface analysis were carried out. The Charpy V impact energy decreases with the decreasing test temperature both for the WM and HAZ, while the proportion of crystal zone on WM and HAZ impact fracture surface increases with the decreasing test temperature. Research results indicate that the welding defects （void and slag） make the impact energy of WM more scattered and lower than that of HAZ.展开更多
文摘The present study is concerned with the effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the joints fabricated by austenitic stainless steel, ferritic stainless steel and duplex stainless steel filler metals were evaluated and the results were reported. From this investigation, it is found that the joints fabricated by duplex stainless steel filler metal showed higher tensile strength and hardness compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Joints fabricated by austenitic stainless steel filler metal exhibited higher ductility and impact toughness compared with the joints fabricated by ferritic stainless steel and duplex stainless steel filler metals.
文摘The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied. Rolled plates of 4 mm thickness have been used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure, and fracture surface morphology of continuous current gas tungsten arc welding （CCGTAW）, pulsed current gas tungsten arc welding （PCGTAW）, and plasma arc welding （PAW） joints are evaluated and the results are compared. It is found that the PAW joints of ferritic stainless steel show superior tensile and impact properties when compared with CCG-TAW and PCGTAW joints, and this is mainly due to lower heat input, finer fusion zone grain diameter, and higher fusion zone hardness.
文摘Based on the theory of hydrogen enhanced localized plasticity of the hydrogen induced cracking and the consideration of the effect of the residual stress produced by eliminated stress heat-treatment, a fractal model of hydrogen induced cracking was presented, and the relationships among the effective surface energy (H), fractal dimension D and stress intensity factor of hydrogen induced cracking, KIH, for welding pipeline under hydrogen environment was set up, from which the relationship of D and KISCC was obtained. The model has been verified experimentally to be correct.
基金supported by the Research and Development Project of Science and Technology of Hebei Province, China (No.03212211D and No.002121186D)
文摘The effects of alloying elements in welding wires and submerged arc welding process on the microstructures and low-temperature impact toughness of weld metals have been investigated. The results indicate that the optimal contents of alloying elements in welding wires can improve the low-temperature impact toughness of weld metals because the proeutectoid ferrite and bainite formations can be suppressed, and the fraction of acicular ferrite increases. However, the contents of alloying elements need to vary along with the welding heat input. With the increase in welding heat input, the contents of alloying elements in welding wires need to be increased accordingly. The microstructures mainly consisting of acicular ferrite can be obtained in weld metals after four-wire submerged arc welding using the wires with a low carbon content and appropriate contents of Mn, Mo, Ti-B, Cu, Ni, and RE, resulting in the high low-temperature impact toughness of weld metals.
文摘The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigatio.n, it is found that gas tungsten arc welded joints of ferritic stainless steel have superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.
文摘The formation mechanism of inclusion in welds with different aluminum contents was determined based on thermodynamic equilibrium in self-shielded flux cored arc welds.Inclusions in welds were systematically studied by optical microscopy,scanning microscopy and image analyzer.The results show that the average size and the contamination rate of inclusions in low-aluminum weld are lower than those in high-aluminum weld.Highly faceted AlN inclusions with big size in the high-aluminum weld are more than those in low-aluminum weld.As a result,the low temperature impact toughness of low-aluminum weld is higher than that of high-aluminum weld.Finally,the thermodynamic analysis indicates that thermodynamic result agrees with the experimental data.
基金the National Natural Science Foundation of China （Grant No. 50375080）.
文摘An experimental setup to excite ultrasonic by modulating electrical arc was applied in the submerged arc welding （SAW） process of 09 MnNiDR steel to study its effect on quality of the welds. Arc-excited ultrasonic energy refines grains of the welds and more acicular ferrite （ AF） appears in the fusion zone. It also enhances impact toughness of the joints at -70 ℃ significantly. With the ultrasonic of 50 kHz, the toughness is improved by 47% in the fusion zone and by 82% in the heataffected zone （HAZ）. The fractography of welds shows that the fracture is changed from cleavage fracture to gliding fracture while applying ultrasonic vibration.
文摘Welded joint impact performances of low-alloy carbon steel plates welded by full-automatic gas metal arc welding （GMAW） were evaluated. To clarity the effect of impact temperature on impact properties of weld metal （WM） and heat- affected zone （ HAZ）, Charpy V impact tests at different temperatures and fracture surface analysis were carried out. The Charpy V impact energy decreases with the decreasing test temperature both for the WM and HAZ, while the proportion of crystal zone on WM and HAZ impact fracture surface increases with the decreasing test temperature. Research results indicate that the welding defects （void and slag） make the impact energy of WM more scattered and lower than that of HAZ.
