Application of Stainless Steel Tape Electrode Submerged Arc Overlay Welding Technology

Literature Overview

This paper by Yu Hao, Ma Ming, and Li Wenyu from Harbin Boiler Works Co., Ltd., published in Welding in 2012 (Issue 12, pages 53-57), presents a systematic investigation of stainless steel tape electrode submerged arc overlay welding technology. The research examined three tape specifications—30 mm × 0.5 mm, 60 mm × 0.5 mm, and 90 mm × 0.5 mm—to establish welding process parameters that produce defect-free overlay deposits with controlled thickness in the range of 6.0 to 6.5 mm.

Process Parameter Investigation

The authors adopted a stepwise parameter optimization approach, progressively adjusting welding current, voltage, travel speed, and stickout length to identify the boundaries between defective and defect-free overlay conditions. This methodology is consistent with the PDCA cycle in welding qualification, where each parameter adjustment is documented, the resulting weld quality is assessed, and the next iteration is planned accordingly.

The study demonstrates that tape width selection directly influences the achievable welding current range and the resulting heat input. Narrower tapes require lower currents and slower travel speeds, while wider tapes permit higher deposition rates and faster production cycles. However, wider tapes also introduce greater challenges in maintaining uniform heat distribution across the weld width, which can lead to incomplete fusion at the edges or excessive dilution in the center.

Quality Assessment Methodology

The quality verification protocol employed in this study is comprehensive and includes mechanical property testing, chemical composition analysis, and ferrite content determination. The ferrite content measurement is particularly significant for stainless steel overlays, as it directly relates to the resistance of the weld metal to cracking and corrosion. For austenitic stainless steel overlays, maintaining a controlled delta ferrite content in the range of 5-15% (per ASTM E490) is essential to ensure adequate crack resistance while preserving the desired corrosion performance.

The mechanical property testing confirms that the overlay deposits achieve adequate hardness and tensile strength for their intended applications. The chemical composition analysis verifies that the overlay metal retains the intended alloying levels, confirming that dilution from the carbon steel substrate remains within acceptable limits for the specified application.

Engineering Applications and Practice

In boiler and heat exchanger manufacturing, stainless steel overlay welding is commonly applied to create corrosion-resistant surfaces on carbon steel pressure boundaries. The tape electrode submerged arc process offers significant productivity advantages over manual or mechanized wire electrode processes, particularly for large-area overlays on flat or gently curved surfaces such as boiler headers, tube sheets, and heat exchanger channels.

The 6.0-6.5 mm overlay thickness achieved in this study represents a practical target for most industrial applications, providing sufficient corrosion-resistant material while minimizing the total wall thickness and associated material costs. Engineers should note that achieving this thickness typically requires multiple passes, with each pass contributing approximately 1.5-2.5 mm of deposit depending on tape width and parameter selection.

A critical practical consideration is the control of interpass temperature. For stainless steel overlays, interpass temperatures should generally be maintained below 150°C to prevent excessive grain growth and potential sensitization in the heat-affected zone. The authors' approach of controlling parameters to produce uniform, smooth overlays suggests careful management of travel speed consistency and torch alignment throughout the welding operation.

Key Reflections

The systematic comparison of three tape widths provides valuable data for process selection, but the study could be further strengthened by including residual stress measurements and hydrogen content analysis. In large-scale overlay applications, residual stress management is critical to prevent distortion and cracking, particularly when overlaying thick carbon steel substrates with austenitic stainless steel deposits that have significantly different thermal expansion coefficients. Additionally, the long-term corrosion performance of the overlay, including resistance to pitting and crevice corrosion in chloride-containing environments, would benefit from dedicated testing beyond the immediate weld quality assessment.

Summary

This paper establishes a reliable process window for stainless steel tape electrode submerged arc overlay welding, demonstrating that consistent 6.0-6.5 mm overlay thickness can be achieved across multiple tape specifications with appropriate parameter control. The comprehensive quality verification approach provides a model for welding procedure qualification, and the productivity advantages of the tape electrode process make it particularly suitable for large-area industrial overlay applications in the power generation and process industries.