Chemical Interaction of Cr-Al-Cu Metal Powders in Aluminum-Assisted Transfer of Chromium in Submerged Arc Welding of Carbon Steel

Abstract

In submerged arc welding (SAW) of chromium containing steels, the chromium in the weld metal is usually sourced from weld wire. Manufacturing of precise weld wire compositions for alloying of the weld metal is expensive. In addition, alloying of weld metal with high levels of copper via weld wire is hindered by work hardening of the weld wire. In the SAW process, a large quantity of oxygen is added to the weld pool. Because chromium has a high affinity for oxygen, the oxygen partial pressure at the weld pool-molten flux interface must be controlled to ensure high recovery of chromium to the weld metal. This study illustrates the application of copper as stabilizer, in conjunction with aluminum, to enhance chromium transfer to the weld pool. The stabilizer effect occurs because the Cr-Al-Cu alloy liquidus temperatures are much lower than the pure Cr liquidus temperature. The result is an increase in the total quantity of Cr, Al, and Cu powder melted into the weld pool. The application of Al powder additions to control the partial oxygen pressure at the molten flux-weld pool interface is confirmed in the presence of Cr and Cu metal powders to ensure the weld metal ppm O content is maintained at the acceptable level of 300 ppm.

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

“…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).…”

“…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].…”

“…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.…”

“…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].…”

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

“…This method is similar to the literaturereported method used in bead-on-plate SAW [31]. The method, as applied here, is the same as in our similar previous works, namely in that the area above the base plate level represents the mass proportion contribution of weld wire and metal powder to the total weld metal mass [29,32]. This mass proportion contribution ratio is defined as the dilution ratio percentage (%DR (wire+MP) ) and is expressed in Equation ( 5).…”