HAYNES® HR-235® alloy is readily weldable by Gas Tungsten Arc (GTAW) and Gas Metal Arc (GMAW) welding processes. For sheet welds and plate root passes, GTAW is suggested. For plate welds, GMAW is preferred. For GMAW, the pulsed spray transfer mode (GMAW-P) is highly suggested. The GMAW-P transfer mode is a stable, low spatter spray transfer at average current levels significantly below that for conventional spray transfer. This results in low-to-moderate weld heat input, which is important to maintain the material properties of Ni-base alloys. Submerged arc welding (SAW) is not recommended as this process is characterized by high heat input to the base metal and slow cooling of the weld. The welding characteristics of HR-235® alloy are comparable to the highly weldable “C-type” alloys and the same general welding guidelines apply. Compared to other metal dusting resistant Ni-base alloys, HR-235® alloy exhibits excellent weldability. For further welding details, please click here for the Welding and Fabrication guide, which contains general welding guidelines applicable to HR-235® alloy.
Wrought forms of HR-235® alloy are furnished in the solution annealed condition, unless otherwise specified, and should be welded in this condition. Welding of cold-worked materials is strongly discouraged, since it accelerates precipitation of secondary phases and induces residual stresses. As such, a full solution anneal in the range of 2100-2150°F (1149-1177°C), depending on specific requirements, followed by rapid air cool or water quench is suggested. Water quenching is recommended when annealing heavy section components and cold-worked structures prior to welding.
Base Metal Preparation
The joint surface and adjacent area should be thoroughly cleaned before welding. All grease, oil, crayon marks, sulfur compounds, and other foreign matter should be removed. Contact with copper or copper-bearing materials in the joint area should be avoided. It is preferable, but not necessary, that the alloy be in the solution-annealed condition when welded.
Filler Metal Selection
For GTAW and GMAW, HR-235® bare filler wire is suggested. For dissimilar metal welds involving HR-235® alloy, please consult with Haynes International for suggested filler metals.
Preheating, Interpass Temperatures, and Postweld Heat Treatment
Preheat is not required and is generally specified as room temperature. Preheat should not be used if the base metal to be welded is above 32°F (0°C). To minimize the precipitation of second phases in regions affected by the heat of welding, a maximum interpass temperature of 200°F (93°C) is recommended for HR-235® alloy. Auxiliary cooling methods may be used between weld passes, as needed, providing that such methods do not introduce contaminants. Post-weld heat treatment is not normally required or suggested for HR-235® alloy. Heat treatment of welded fabrications may be required for other reasons, such as stress relief.