Overlay Welding Repair of Converter Support Rings in Steelmaking

Literature Overview

The paper by Qiu Fuxiang and Xu Kejian, published in Welding Technology (2000, Vol. 29, No. 4, p. 44), addresses the overlay welding repair of converter support rings in the steelmaking industry. The authors, from the Construction Company Engineering Technology Department of Xiangtan Steel Group Co., Ltd., describe a practical repair technique for a critical component in the basic oxygen furnace (BOF) converter system. Although the paper is brief, it represents a valuable engineering practice document that addresses a specific and recurring maintenance challenge in the steel industry.

Component Description and Failure Mode

The converter support ring is a critical structural component that supports the converter shell during the steelmaking process. It is subjected to extreme conditions, including:

High temperatures from the molten steel and slag.
Thermal cycling due to the repeated heating and cooling of the converter.
Mechanical loading from the weight of the converter and the forces generated during tilting and pouring.
Erosion and corrosion from the molten materials.

The primary failure mode of the support ring is wear and erosion, which reduces the effective thickness of the component and compromises its structural integrity. When the wear becomes excessive, the support ring must be repaired or replaced.

Overlay Welding Repair Approach

The repair approach described in the paper involves the application of a wear-resistant overlay weld layer to the worn surface of the support ring. The key aspects of the repair process include:

Surface preparation: The worn surface is cleaned and prepared to ensure proper fusion of the overlay weld deposit. This may involve grinding, chipping, or other mechanical methods to remove loose material and create a sound base for the weld.
Welding electrode selection: A wear-resistant welding electrode is selected to provide a deposit with the appropriate hardness and erosion resistance. The electrode must also be compatible with the base material to avoid cracking.
Welding process: The overlay weld is applied using a suitable welding process, such as shielded metal arc welding (SMAW) or submerged arc welding (SAW), depending on the accessibility and thickness of the deposit required.
Post-repair machining: After welding, the repaired surface may be machined to restore the original dimensions and surface finish.

Engineering Significance

The repair of converter support rings is a routine maintenance activity in the steel industry, but it is not trivial. The component is critical to the safe operation of the converter, and any failure could lead to serious safety incidents. The overlay welding repair approach provides a cost-effective and reliable solution that extends the service life of the component.

The paper, while brief, contributes to the body of engineering knowledge on the repair of steelmaking components. It demonstrates that overlay welding is a viable repair technique for components subjected to severe wear and erosion conditions.

Key Considerations for Converter Support Ring Repair

Consideration	Description	Importance
Wear mechanism	Abrasion, erosion, or corrosion	Determines deposit material selection
Temperature exposure	Maximum operating temperature	Determines deposit stability
Mechanical loading	Static and dynamic loads	Determines deposit thickness
Thermal cycling	Number of cycles and temperature range	Determines deposit fatigue resistance
Base material compatibility	Weldability of the support ring material	Determines welding process and parameters
Repair accessibility	Ease of access to the worn surface	Determines welding process selection

Study Insights and Reflections

This paper, though concise, represents the practical application of overlay welding technology in the steel industry. The repair of converter support rings is a common maintenance activity, and the techniques described can be applied to similar components in other industries.

The brevity of the paper limits the depth of technical detail provided, but the fundamental approach is sound. The selection of a wear-resistant overlay weld deposit, proper surface preparation, and appropriate welding parameters are the key elements of the repair process.

One area that could be expanded in future work is the detailed metallurgical characterization of the repair deposit. Understanding the microstructure and phase composition of the overlay weld would provide a more rigorous basis for material selection and process optimization. Additionally, the long-term performance of repaired support rings under actual operating conditions would be valuable information for the industry.

The paper also highlights the importance of practical engineering documentation. Even when the technical details are not fully elaborated, the description of a successful repair technique can provide valuable guidance to other engineers facing similar challenges.