Gene Vogel
Pump & Vibration Specialist
Electrical Apparatus Service Association
St. Louis, MO
The paper "Steel—Metallurgy and Practical Application of Various Grades of Steel" by Gene Vogel, presented at the EASA Convention 2016, provides an in-depth exploration of steel alloys, their composition, processing, and applications, particularly in the context of machinery repairs and replacement shafts. Vogel emphasizes the importance of selecting the appropriate type or grade of steel for specific applications, drawing on both practical application information and technical metallurgy theory.
Steel is an iron-carbon alloy, with carbon content varying from 0.01% to 5%. Increased carbon content generally enhances strength but reduces malleability. The paper explains that the characteristics of steel are also influenced by heat treating, processing, and the presence of other alloy elements. Vogel likens the process of making steel to cooking, where the right ingredients and proper processing yield the desired results.
The paper references EASA’s "Mechanical Repair Fundamentals of Electric Motors" manual, which provides basic recommendations for steel types and grades for manufacturing replacement shafts. Vogel notes that manufacturers use different alloys and transition points for higher-strength steels, depending on the application and horsepower. Common types of engineering steel include carbon steel, stainless steel, and duplex steel, each with various grades designated by standards such as SAE, EN, BS, and ISO.
To determine the alloy of a part to be replaced, Vogel suggests providing a sample to a test laboratory for analysis. Spectroscopy can identify the approximate concentrations of alloy elements, while portable X-ray fluorescence instruments offer quantitative information. For practical purposes, the choice of material often balances strength, corrosion resistance, machinability, and cost.
The paper discusses the properties of common shaft materials, including their tensile and yield strengths, and highlights the importance of pump shaft quality (PSQ) shafting for certain applications. PSQ shafting is normalized to remove residual stress and precision ground to increase fatigue cycle life.
Vogel explains that the properties of alloy steel depend not only on alloy content but also on microstructure, which is influenced by processing methods and heat treating. Heat treating involves holding the steel at specific temperatures for set periods, affecting the microstructure and resulting properties such as tensile strength, yield strength, ductility, hardness, machinability, and magnetic properties.
The paper includes a phase diagram to illustrate the effect of heat treating on the iron-carbon solution, showing how different microstructures form at various stages of solidification. Stress-strain diagrams are used to explain the relationship between stress, strain, yield strength, ultimate strength, and fracture strength. Vogel also addresses machinability, magnetic properties, and corrosion resistance, noting that these factors are critical for specific applications.
In conclusion, the paper provides a comprehensive overview of the science of metallurgy and practical considerations for selecting and processing steel alloys for machinery components. Vogel emphasizes the importance of understanding alloy content, heat treating, and processing methods to achieve the desired properties in the finished product.
Key Points Covered:
- Importance of selecting the appropriate steel type or grade for specific applications
- Composition and characteristics of steel alloys
- Recommendations for steel types and grades for replacement shafts
- Methods for determining alloy content of parts
- Properties of common shaft materials and PSQ shafting
- Influence of microstructure and heat treating on steel properties
- Explanation of phase diagrams and stress-strain diagrams
- Considerations for machinability, magnetic properties, and corrosion resistance
Key Takeaways:
- Selecting the right steel type or grade is crucial for machinery repairs and replacement shafts.
- Steel properties are influenced by carbon content, alloy elements, heat treating, and processing methods.
- Practical considerations include balancing strength, corrosion resistance, machinability, and cost.
- Understanding microstructure and heat treating is essential for achieving desired properties.
- Phase diagrams and stress-strain diagrams help explain the effects of heat treating and mechanical properties.
- Machinability, magnetic properties, and corrosion resistance are important for specific applications.
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