Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding: Application of Al-Cr-Ti-Cu Unconstrained Metal Powders

Coetsee, Theresa; Bruin, Frederik De

doi:10.3390/pr10030452

Cited by 14 publications

(51 citation statements)

References 24 publications

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“…Area 2 equals the area between line B and line C and is the proportion of the weld metal area that was The slight increase in the silicon and manganese content of the MP8 weld metal, as compared to the BC weld metal, is due to the aluminothermic reduction in MnO and SiO 2 content from the slag. This effect was identified in our previously reported work on aluminium-assisted alloying of different metal powders in SAW [31][32][33][34][35][36][37]. The total ppm O in the MP8 weld metal was significantly lowered (162 ppm O) as compared to the BC weld metal (499 ppm O).…”

Section: Mass Balancesupporting

confidence: 55%

“…The total ppm O in the MP8 weld metal was significantly lowered (162 ppm O) as compared to the BC weld metal (499 ppm O). This lowering to 162 ppm O in the MP8 weld metal is due to the de-oxidiser effect of aluminium at the weld pool-slag interface [31][32][33][34][35][36][37].…”

Section: Chemical Analysesmentioning

confidence: 94%

“…Mass measurements and mass balance calculations were combined as described in this section. This calculation procedure is the same procedure applied in our previous studies [33][34][35][36][37]. The steel plate mass was measured before and after the SAW test run.…”

Section: Mass Balancementioning

confidence: 99%

“…Area 2 equals the area between line B and line C and is the proportion of the weld metal area that was contributed from the melting of the base plate. Here, this area ratio is defined as the dilution ratio as previously reported and named (%DR (wire+MP) ) in the following expressions [33][34][35][36][37].…”

Section: Mass Balancementioning

confidence: 99%

“…Processes 2022, 10, x FOR PEER REVIEW 7 of 18 contributed from the melting of the base plate. Here, this area ratio is defined as the dilution ratio as previously reported and named (%DR(wire+MP)) in the following expressions [33][34][35][36][37]. The mass of aluminium, chromium, and nickel added to the SAW test run were calculated from Equations ( 2)-( 4).…”

Section: Mass Balancementioning

confidence: 99%

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Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding with Al-Cr-Ni Unconstrained Metal Powders: Thermodynamic Interpretation of Gas Reactions

Coetsee

Bruin

2022

Processes

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Unconstrained metal powders of chromium and nickel, in combination with aluminium, were used in the submerged arc welding (SAW) process to simplify weld metal alloying. Unconstrained metal powders refer to non-alloyed metal powders that are not constrained in tubular wire, such as fluxed-cored and metal-cored wire. Aluminium powder is used to control the oxygen potential at the molten flux–weld pool interface. The results presented here show that the addition of aluminium powder to the weld metal enhances Cr and Ni yields to 89% for Cr and 91% for Ni, compared to lower values reported in pre-alloyed powder application. Alloying of the carbon steel in the base plate and weld wire combination was achieved at 6.0% Cr, 6.2% Ni, and 4.5% Al, with the weld metal oxygen controlled to 162 ppm O. Thermodynamic analysis was applied to investigate the likely gas reactions in the arc cavity emanating from the chemical interaction between Cr, Ni, and Al. The effects of gas-based chemical reactions on the yield of Cr and Ni to the weld pool are discussed and incorporated into our SAW reaction flow diagram. Overall SAW process productivity gains can be accomplished by using unconstrained metal powders to alloy the weld metal because expensive and time consuming steps, such as the manufacturing of alloyed wire and alloyed powder, can now be eliminated.

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Section: Mass Balancesupporting

confidence: 55%

Section: Chemical Analysesmentioning

confidence: 94%

Section: Mass Balancementioning

confidence: 99%

Section: Mass Balancementioning

confidence: 99%

Section: Mass Balancementioning

confidence: 99%

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Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding with Al-Cr-Ni Unconstrained Metal Powders: Thermodynamic Interpretation of Gas Reactions

Coetsee

Bruin

2022

Processes

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Limits on Ti Element Transfer in Submerged Arc Welding: Thermochemical Analysis

Coetsee,

De Bruin

2024

steel research int.

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TiO2 inclusion formation in the weld pool is required to produce potent nucleation sites for acicular ferrite microstructure formation. Weld metal oxygen content must be limited to ensure acceptable materials properties, although sufficient oxygen is required for inclusion formation. Weld pool oxygen is sourced from the decomposition of flux oxides. Weld metal oxygen is controlled with flux chemistry formulation by CaF2 dilution of oxides. In conventional submerged arc welding (SAW), the flux is the source of weld metal Ti. Transfer of Ti from the slag appears to be limited to 400 parts per million (ppm). SAW modification by metal powder additions changes the element transfer reactions. Thermochemical analysis is applied to explain the limitations in Ti transfer from the slag, compared to improved reaction conditions for Ti element transfer in the aluminum‐assisted Ti alloying of weld metal. Low TiO2 activity due to low flux TiO2 content from CaF2 dilution and Ti loss from Ti‐fluoride gas formation limits Ti transfer from slag. Aluminum‐assisted alloying of the weld metal shifts the gas composition from Ti‐fluoride formation to Al‐fluoride formation and lowers the system partial oxygen pressure to increase the weld metal Ti content, with acceptable ppm O remaining in the weld metal.

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Timed Thermodynamic Process Model Applied to Submerged Arc Welding Modified by Aluminium-Assisted Metal Powder Alloying

Coetsee,

De Bruin

2024

JOM

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An EERZ (effective equilibrium reaction zone) model was applied to the modified SAW (submerged arc welding) process to simulate the SAW process metallurgy in the gas-slag-metal reaction system. The SAW process was modified by adding Al as a de-oxidizer with alloying metal powders of Cr, Cu, and Ti. The static gas-slag-metal equilibrium model can accurately calculate the weld metal oxygen content (ppm O) for conventional SAW but not for the modified SAW process. The static equilibrium model overpredicts the reaction of Al. EERZ model runs were made for 2000–2500°C because this is the reported temperature range in the SAW arc cavity. The weld metal composition was adequately calculated, especially the weld metal ppm O, at the following effective equilibrium temperatures: 2400°C for Al-Cr additions, 2200°C for Al-Cr-Cu additions, and 2000°C for Al-Cr-Cu-Ti additions. Model results show that Ti metal powder can serve a de-oxidizer role in the presence of Al, resulting in Ti loss to the slag. Ti is also lost to the gas phase as TiF3(g) and TiF2(g) compared to little loss of Cr to the gas phase as Cr(g) and CrO to the slag phase.

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Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding: Application of Al-Cr-Ti-Cu Unconstrained Metal Powders

Cited by 14 publications

References 24 publications

Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding with Al-Cr-Ni Unconstrained Metal Powders: Thermodynamic Interpretation of Gas Reactions

Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding with Al-Cr-Ni Unconstrained Metal Powders: Thermodynamic Interpretation of Gas Reactions

Limits on Ti Element Transfer in Submerged Arc Welding: Thermochemical Analysis

Timed Thermodynamic Process Model Applied to Submerged Arc Welding Modified by Aluminium-Assisted Metal Powder Alloying

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