Selection of Welding Materials for Vertical Mill Roller Surfacing Wear-Resistant Layer

Literature Overview

This paper, published in Mining Machinery (2013, Vol. 41, No. 6, pp. 58–61), authored by Quan Jianjun, Liu Xushou, Bai Jinsheng, Duan Shixin, and Wu Jianying from CITIC Heavy Industries Co., Ltd., presents a systematic comparative evaluation of four wear-resistant welding materials from four different manufacturers for application on vertical mill rollers. The study employs a multi-criteria assessment approach including deposited metal hardness, chemical composition analysis, abrasive wear testing, metallographic examination, and impact weight loss testing. The results provide quantitative guidance for roller manufacturers in selecting cost-effective wear-resistant welding materials.

Core Technical Points

Multi-Criteria Evaluation Methodology

The evaluation methodology employed in this study is particularly noteworthy for its comprehensive approach, which goes beyond simple hardness measurements to include multiple performance indicators. The five evaluation criteria—deposited metal hardness, chemical composition, abrasive wear resistance, microstructure quality, and impact resistance—collectively address the key performance requirements for vertical mill roller surfacing layers. This multi-dimensional assessment approach is superior to single-parameter evaluation, as it captures the trade-offs inherent in wear-resistant alloy design.

Comparative Results of Four Welding Materials

The four welding materials evaluated represent different alloy systems and manufacturers, each with distinct performance characteristics. The comparative analysis reveals that no single material excels in all criteria simultaneously, underscoring the importance of multi-criteria evaluation in material selection.

Microstructural Characteristics and Their Influence on Performance

The microstructural analysis reveals distinct differences among the four materials. Material B and Material D exhibit fine-grained martensitic structures with uniformly dispersed carbide particles, which contribute to their superior abrasive wear resistance. Material A shows a mixed martensitic-bainitic structure with moderate carbide distribution, providing adequate but not exceptional wear performance. Material C exhibits a coarser microstructure with irregular carbide morphology, correlating with its lower wear resistance. The carbide morphology—whether spherical, plate-like, or network-forming—has a significant influence on both abrasive and impact wear resistance, with fine, uniformly distributed carbides generally providing the best overall performance.

Engineering Practice Considerations

Application-Specific Material Selection

Vertical mill rollers operate under complex loading conditions involving grinding pressure, sliding friction, impact from material feed, and thermal cycling. The selection of surfacing material must account for the specific operating conditions of each application:

Process Parameters for Vertical Mill Roller Surfacing

The surfacing of vertical mill rollers typically employs submerged arc welding (SAW) or flux-cored arc welding (FCAW) for high deposition rates and consistent quality. The roller surface is usually machined to a precise geometry before surfacing, and the deposited layer must maintain dimensional accuracy within tight tolerances (typically ±0.5 mm) to ensure proper grinding performance. Multi-pass deposition is standard, with each pass deposited to a thickness of 3–5 mm, and the total surfacing thickness typically ranging from 15–25 mm depending on the roller design.

Key Questions and Reflections

The cost-performance analysis presented in this study is particularly valuable for engineering decision-making, as it moves beyond absolute performance metrics to address the practical economic considerations that drive material selection in industrial applications. Material D, despite exhibiting the highest absolute wear resistance, does not necessarily represent the optimal choice if its significantly higher cost cannot be justified by proportional service life extension. The cost-performance ratio analysis provides a rational framework for material selection that balances technical performance with economic constraints.

However, the study does not address the long-term field performance of the evaluated materials under actual vertical mill operating conditions. Laboratory wear tests, while providing controlled and repeatable data, may not fully capture the complex interactions between the surfacing layer and the material being ground, including thermal effects, chemical interactions, and variable loading patterns. I recommend supplementing laboratory evaluation with accelerated field trials on representative rollers, with periodic in-service inspection to track wear progression and identify failure modes.

Additionally, the study does not consider the effect of surfacing layer repairability. In practice, vertical mill rollers may require re-surfacing after partial wear, and the compatibility of the new deposit with the previously deposited layer should be evaluated. Differences in thermal expansion coefficients between the original and repair surfacing layers can introduce residual stresses that compromise the integrity of the repaired surface.

Study Insights and Outlook

This paper exemplifies a rigorous, multi-criteria approach to welding material selection that is directly applicable to engineering practice. The systematic comparison of four commercially available materials, evaluated across five performance dimensions, provides a template for material selection studies in other surfacing applications. The emphasis on cost-performance analysis, rather than absolute performance alone, reflects a mature engineering perspective that acknowledges the economic realities of industrial operations. Engineers responsible for vertical mill roller maintenance programs should adopt this multi-dimensional evaluation framework and supplement laboratory data with field performance tracking to develop comprehensive material selection guidelines tailored to their specific operating conditions and maintenance strategies.