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Changpin Chou - One of the best experts on this subject based on the ideXlab platform.

  • the study of nitrogen in argon gas on the angular distortion of austenitic stainless steel Weldments
    Journal of Materials Processing Technology, 2003
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    Abstract The objective of this study was to investigate the effect of nitrogen added in argon shielding gas on the angular distortion of austenitic stainless steels. An autogenous gas tungsten arc Welding was conducted on austenitic stainless steels 304 and 310 to produce a bead-on-Plate Weld. The delta-ferrite content of Welds was measured by using Ferritscope. The angular distortion of Weldments was determined by using the mean vertical displacement method (MVDM). The present results indicate that the retained ferrite content in Type 304 stainless steel Weld metals was rapidly reduced as the nitrogen addition in argon shielding gas was increased. The Welding angular distortion was raised with the increase of the amount of nitrogen added in the shielding gas. This experimental result also found that the existence of retained ferrite microstructure within the austenitic matrix has a beneficial effect in reducing Welding distortion tendency of austenitic stainless steel Weldment.

  • the effect of pulsed gta Welding on the residual stress of a stainless steel Weldment
    Journal of Materials Processing Technology, 2002
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    Abstract The objective of this study was to investigate the effect of pulsed GTA Welding parameters on the residual stress of the Weldment. Autogenous gas tungsten arc Welding was applied on SUS 304 and SUS 310 stainless steels to produce a bead-on-Plate Weld. The residual stress was determined by using the hole-drilling strain-gage method of ASTM standard E837. The experimental results show that a greater pulse frequency, a larger pulse spacing, a greater amplitude ratio, and a greater duration ratio can reduce the magnitude of the residual stress in the austenitic stainless steel Weldment. The residual stress of the 310 stainless steel Weldment is greater than that of the 304 stainless steel Weldment under the same Welding conditions because of its lower thermal conductivity and thermal diffusivity. The experimental results also showed that pulsed current Welding has a smaller range of the tensile residual stress zone as compared to that of constant current Welding because of its lesser amount of heat input.

  • effect of pulsed gas tungsten arc Welding on angular distortion in austenitic stainless steel Weldments
    Science and Technology of Welding and Joining, 2001
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    AbstractThe effect of the parameters of the pulsed gas tungsten arc Welding (GTAW) process on the angular distortion in austenitic stainless steel Weldments was investigated. Autogenous GTAW was conducted on types 304 and 310 stainless steels to produce a bead on Plate Weld. The Weldment thermal cycle was recorded during pulsed GTAW to investigate the influence of thermal stress. Angular distortion was determined by using the mean vertical displacement method. The experimental results indicate that higher pulse frequency, smaller pulse spacing, greater amplitude ratio, and greater duration ratio can reduce the angular distortion. The angular distortion of type 310 stainless steel Weldments was greater than that of type 304 Weldments under the same Welding conditions because of the lower thermal conductivity and thermal diffusivity of type 310.

Kuanghung Tseng - One of the best experts on this subject based on the ideXlab platform.

  • the study of nitrogen in argon gas on the angular distortion of austenitic stainless steel Weldments
    Journal of Materials Processing Technology, 2003
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    Abstract The objective of this study was to investigate the effect of nitrogen added in argon shielding gas on the angular distortion of austenitic stainless steels. An autogenous gas tungsten arc Welding was conducted on austenitic stainless steels 304 and 310 to produce a bead-on-Plate Weld. The delta-ferrite content of Welds was measured by using Ferritscope. The angular distortion of Weldments was determined by using the mean vertical displacement method (MVDM). The present results indicate that the retained ferrite content in Type 304 stainless steel Weld metals was rapidly reduced as the nitrogen addition in argon shielding gas was increased. The Welding angular distortion was raised with the increase of the amount of nitrogen added in the shielding gas. This experimental result also found that the existence of retained ferrite microstructure within the austenitic matrix has a beneficial effect in reducing Welding distortion tendency of austenitic stainless steel Weldment.

  • the effect of pulsed gta Welding on the residual stress of a stainless steel Weldment
    Journal of Materials Processing Technology, 2002
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    Abstract The objective of this study was to investigate the effect of pulsed GTA Welding parameters on the residual stress of the Weldment. Autogenous gas tungsten arc Welding was applied on SUS 304 and SUS 310 stainless steels to produce a bead-on-Plate Weld. The residual stress was determined by using the hole-drilling strain-gage method of ASTM standard E837. The experimental results show that a greater pulse frequency, a larger pulse spacing, a greater amplitude ratio, and a greater duration ratio can reduce the magnitude of the residual stress in the austenitic stainless steel Weldment. The residual stress of the 310 stainless steel Weldment is greater than that of the 304 stainless steel Weldment under the same Welding conditions because of its lower thermal conductivity and thermal diffusivity. The experimental results also showed that pulsed current Welding has a smaller range of the tensile residual stress zone as compared to that of constant current Welding because of its lesser amount of heat input.

  • effect of nitrogen addition to shielding gas on residual stress of stainless steel Weldments
    Science and Technology of Welding and Joining, 2002
    Co-Authors: Kuanghung Tseng, C P Chou
    Abstract:

    The objective of the present study was to investigate the effect of nitrogen additions to the shielding gas on the ferrite content and residual stress in austenitic stainless steels. Autogenous gas tungsten arc (GTA) Welding was applied on austenitic stainless steels 304 and 310 to produce a bead on Plate Weld. The delta ferrite content of the Weld metals was measured using a Ferritscope. The residual stress in the Weldments was determined using the hole drilling strain gauge method. The present results indicated that the retained delta ferrite content in type 304 stainless steel Weld metals decreased rapidly as nitrogen addition to the argon shielding gas was increased. The Welding residual stress increased with increasing quantity of added nitrogen in the shielding gas. It was also found that the tensile residual stress zone in austenitic stainless steel Weldments was extended as the quantity of added nitrogen gas in the argon shielding gas was increased.

  • effect of pulsed gas tungsten arc Welding on angular distortion in austenitic stainless steel Weldments
    Science and Technology of Welding and Joining, 2001
    Co-Authors: Kuanghung Tseng, Changpin Chou
    Abstract:

    AbstractThe effect of the parameters of the pulsed gas tungsten arc Welding (GTAW) process on the angular distortion in austenitic stainless steel Weldments was investigated. Autogenous GTAW was conducted on types 304 and 310 stainless steels to produce a bead on Plate Weld. The Weldment thermal cycle was recorded during pulsed GTAW to investigate the influence of thermal stress. Angular distortion was determined by using the mean vertical displacement method. The experimental results indicate that higher pulse frequency, smaller pulse spacing, greater amplitude ratio, and greater duration ratio can reduce the angular distortion. The angular distortion of type 310 stainless steel Weldments was greater than that of type 304 Weldments under the same Welding conditions because of the lower thermal conductivity and thermal diffusivity of type 310.

Her-yueh Huang - One of the best experts on this subject based on the ideXlab platform.

  • Effects of shielding gas composition and activating flux on GTAW Weldments
    Materials & Design, 2009
    Co-Authors: Her-yueh Huang
    Abstract:

    Abstract This study investigated the effects of shielding gas composition and activating flux on Weld morphology, angular distortion, retained delta-ferrite content, mechanical properties and hot cracking susceptibility. An autogenous gas tungsten arc Welding process was used on austenitic stainless steel to produce a bead-on-Plate Weld. The nitrogen content in the argon-based shielding gas was in the range of 2.5–10 vol.%. Activating flux materials consisted of a manganese oxide powder and zinc oxide powder mixture. The results showed that the penetration and cross-sectional area of the Weld increased with the increase of nitrogen added to the argon-base shielding gas. An increase in shielding gas nitrogen content had markedly reduced the angular distortion of the Weldment. Increasing the nitrogen increased the tensile strength and hardness but reduced the retained delta-ferrite. The hot cracking susceptibility of the austenitic stainless steel Welds increased as the nitrogen content increased. Activating flux plays a major role than nitrogen added in argon shielding gas, which influenced the various properties of austenitic stainless steel TIG Welds.

E C Oliver - One of the best experts on this subject based on the ideXlab platform.

  • residual stress in a thick section high strength t butt Weld
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008
    Co-Authors: S V Pearce, V Linton, E C Oliver
    Abstract:

    Residual stresses in a structure are generated as a result of the various fabrication and Welding processes used to make the component. Being able to quantify these residual stresses is a key step in determining the continuing integrity of a structure in service. In this work, the residual stresses around a high strength, quenched and tempered steel T-butt web to curved Plate Weld have been measured using neutron strain scanning. The results show that the residual stresses near the Weld were dominated by the Welding residual stresses, while the stresses further from the Weld were dominated by the bending residual stresses. The results suggest that the combination of Welding-induced residual stress and significant pre-Welding residual stress, as in the case of a thick bent section of Plate can significantly alter the residual stress profile from that in a flat Plate.

Rachel Thomson - One of the best experts on this subject based on the ideXlab platform.

  • Microstructural characterization of the heat-affected zones in grade 92 steel Welds: Double-pass and multipass Welds
    2018
    Co-Authors: G. D. West, J. A. Siefert, J. D. Parker, Rachel Thomson
    Abstract:

    The microstructure in the heat affected zone (HAZ) of multipass Welds typical of those used in power plant made from 9 wt.% chromium martensitic Grade 92 steel is complex. There is therefore a need for systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel Welds manufactured using traditional arc Welding processes in order to understand possible failure mechanisms after long term service. In this study, the microstructure in the HAZ of an as-fabricated two-pass bead-on-Plate Weld on a parent metal of Grade 92 steel has been systematically investigated and compared to a complex, multi-pass thick section Weldment using an extensive range of electron and ion-microscopy based techniques. A dilatometer has been used to apply controlled thermal cycles to simulate the microstructures in distinctly different regions in a multi-pass HAZ using sequential thermal cycles. A wide range of microstructural properties in the simulated materials were characterised and compared with the experimental observations from the Weld HAZ. It has been found that the microstructure in the HAZ can be categorized by a combination of sequential thermal cycles experienced by the different zones within the complex Weld metal, using the terminology developed for these regions based on a simpler, single pass bead on Plate Weld, which have been systematically categorised as Complete Transformation (CT), Partial Transformation (PT) and Over Tempered (OT)

  • The influence of thermal cycles on the microstructure of grade 92 steel
    2017
    Co-Authors: G. D. West, J. A. Siefert, J. D. Parker, Rachel Thomson
    Abstract:

    The microstructure in the heat-affected zone (HAZ) of Welds made from the 9 wt pct chromium martensitic Grade 92 steel is complex and has not yet been completely understood. There is a lack of systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel Welds as a function of the Welding process. In this study, the microstructure in the HAZ of an as-fabricated single-pass bead-on-Plate Weld on a parent metal of Grade 92 steel was systematically investigated by using an extensive range of electron and ion-microscopy-based techniques. A dilatometer was used to apply controlled thermal cycles to simulate the microstructures in the different regions of the HAZ. A wide range of microstructural properties in the simulated materials were then characterized and compared with the experimental observations from the Weld HAZ. It was found that the microstructure in the HAZ of a single-pass Grade 92 steel Weld can be categorized as a function of a decreasing peak temperature reached as (1) the completely transformed (CT) region, in which the original matrix is completely reaustenitized with complete dissolution of the pre-existing secondary precipitate particles; (2) the partially transformed (PT) region, where the original matrix is partially reaustenitized along with a partial dissolution of the secondary precipitate particles from the original matrix; and (3) the overtempered (OT) region, where the pre-xisting precipitate particles coarsen. The PT region is considered to be the susceptible area for damage in the commonly reported HAZ failures in Weldments constructed from these types of steels