Domestication Analysis of Stainless Steel Welding Strip for Strip Surfacing

Literature Overview

This technical paper, published in Petroleum Engineering Construction (1991, Vol. 17, No. 3, pp. 7–9) by Zhang Yong and Wang Jiahui from the General Machinery Research Institute under the Ministry of Machinery Industry, addresses the domestication challenges of stainless steel welding strip for strip surfacing applications in the petroleum and chemical industries. The authors review the status of imported stainless steel welding strips, analyze the technical problems encountered during domestic trial production, and propose solutions for achieving domestic self-sufficiency. This work is historically important as it documents the early efforts to develop domestic capabilities in a critical welding consumable category.

Technical Background and Industry Context

Strip surfacing (also known as submerged arc strip surfacing or twin-wire surfacing) is a high-productivity welding process that uses a continuous strip of welding material as the filler metal. The process is widely used for:

• Large-diameter pipe surfacing in petrochemical pipelines
• Wear-resistant overlays on large equipment
• Corrosion-resistant cladding on carbon steel components
• Thick overlay builds on structural components

The use of stainless steel welding strip for corrosion-resistant overlays is particularly important in the petroleum and chemical industries, where components are exposed to aggressive corrosive environments. At the time of this study (1991), China relied heavily on imported stainless steel welding strips, creating supply chain vulnerabilities and cost pressures.

Technical Requirements for Stainless Steel Welding Strip

The domestication of stainless steel welding strip requires meeting several stringent technical requirements:

Chemical Composition Control

The chemical composition of stainless steel welding strip must be carefully controlled to achieve the desired corrosion resistance and mechanical properties in the weld deposit. Key elements include:

• Chromium (Cr) — Primary corrosion-resistant element; typically 18–30% for austenitic grades
• Nickel (Ni) — Stabilizes austenite structure; typically 8–22%
• Molybdenum (Mo) — Enhances pitting corrosion resistance; typically 2–6%
• Carbon (C) — Must be controlled at low levels (<0.03%) to prevent intergranular corrosion
• Sulfur (S) and Phosphorus (P) — Must be minimized (<0.01%) to reduce hot cracking susceptibility

The narrow composition windows for these elements present significant challenges for domestic producers, particularly in terms of:

1. Raw material quality — Domestic stainless steel ingots may have wider composition variations
2. Melting process control — Requires advanced metallurgical processes (VIM, AOD, EAF)
3. Rolling process control — Must maintain composition homogeneity during hot and cold rolling

Problems Encountered During Domestic Trial Production

The authors identify several critical problems encountered during the domestic trial production of stainless steel welding strip:

1. Composition Uniformity Issues

The domestic trial production exhibited significant variations in chemical composition across the strip length and width. This was attributed to:

• Incomplete homogenization of the initial ingot
• Inadequate control of the rolling process
• Insufficient heat treatment to achieve uniform composition

Impact: Composition variations lead to inconsistent weld deposit properties, causing quality issues in downstream applications.

2. Surface Defects

The domestic strips exhibited surface defects including:

• Surface cracks from rolling
• Oxide inclusions from inadequate deoxidation
• Surface roughness from insufficient finishing

Impact: Surface defects can initiate cracks during welding and reduce the quality of the overlay.

3. Dimensional Inconsistency

The domestic strips showed poor control of thickness and width tolerances:

• Thickness variations exceeding ±0.1 mm
• Width variations exceeding ±1 mm
• Edge quality issues (burrs, tears)

Impact: Dimensional inconsistencies affect welding process stability and overlay uniformity.

4. Weldability Issues

The domestic strips exhibited weldability problems including:

• Excessive hydrogen pickup during welding
• Poor arc stability
• Increased spatter
• Higher porosity rates in weld deposits

Impact: Weldability issues reduce productivity and increase defect rates.

Solutions and Recommendations

Based on the analysis of the problems encountered, the authors propose the following solutions:

1. Improved melting processes — Adopt vacuum induction melting (VIM) or argon oxygen decarburization (AOD) processes to achieve tighter composition control and lower impurity levels.
2. Enhanced rolling technology — Implement multi-step rolling with intermediate annealing to achieve uniform composition and improved surface quality.
3. Advanced finishing processes — Add cold rolling and surface finishing steps to achieve dimensional accuracy and smooth surface finish.
4. Process optimization for welding — Develop welding process parameters specifically tailored to the domestic strip composition, including optimized shielding gas composition and welding current/voltage settings.
5. Quality assurance system — Implement rigorous quality control at each production stage, including chemical analysis, mechanical testing, and welding performance evaluation.

Engineering Practice Integration

The domestication of stainless steel welding strip has significant implications for the petroleum and chemical industries:

• Cost reduction — Domestic production can reduce costs by 30–50% compared to imported strips
• Supply security — Eliminates dependence on foreign suppliers and reduces supply chain risks
• Technical support — Domestic producers can provide better technical support and faster response times
• Customization — Domestic producers can develop specialized compositions for specific applications

However, engineers must be aware that domestic products may require additional qualification testing before being accepted for critical applications. The qualification process should include:

1. Chemical analysis — Verify composition meets specification requirements
2. Mechanical testing — Confirm tensile strength, elongation, and hardness
3. Welding performance testing — Evaluate weldability, arc stability, and deposit properties
4. Corrosion testing — Verify corrosion resistance meets application requirements
5. Long-term performance evaluation — Monitor service performance over extended periods

Study Insights and Implications

This paper provides valuable insights into the challenges of domesticating specialized welding consumables. The technical problems identified are representative of the broader challenges faced when transitioning from imported to domestic production of high-quality welding materials.

The key insight is that domestication requires not only technical capability but also a comprehensive approach that addresses the entire production chain from raw materials through final product qualification. The problems encountered during trial production highlight the importance of process control, quality assurance, and continuous improvement.

For engineers involved in specifying welding consumables, this study underscores the importance of supplier qualification and product verification. Domestic products can achieve equivalent performance to imported products, but this requires rigorous testing and ongoing quality monitoring.

The historical context of this study is also important. In 1991, China's welding consumable industry was in an early stage of development, and the challenges identified in this paper have largely been addressed through subsequent technological advances. However, the fundamental principles of material development, process control, and quality assurance remain relevant today.

For contemporary engineers, the study serves as a reminder that the domestication of critical materials requires sustained investment, technical expertise, and a commitment to quality. The success of domestic stainless steel welding strip production today is built on the foundational work documented in this paper and the subsequent efforts of engineers and researchers in the field.