| Aspect | ASTM A574 Specification | ASTM A193 Specification |
|---|---|---|
| Material Type | Covers alloy steel socket head cap screws. | Covers alloy steel and stainless steel bolting materials for high-temperature and high-pressure service. |
| Primary Application | Used in applications requiring high tensile strength and durability, typically in mechanical assemblies. | Used primarily in pressure vessels, valves, flanges, and fittings for high-temperature or high-pressure environments. |
| Mechanical Properties | Requires a minimum tensile strength of 170,000 psi (1172 MPa) for alloy steel. | Varies by grade; for example, Grade B7 requires a minimum tensile strength of 125,000 psi (862 MPa). |
| Chemical Composition | Requires specific alloying elements like carbon, manganese, phosphorus, sulfur, and others depending on the alloy grade. | Specifies chemical composition requirements, particularly for alloy and stainless steel, tailored for corrosion and heat resistance. |
| Heat Treatment Requirements | Typically requires quenching and tempering to achieve the desired mechanical properties. | Heat treatment is required for most grades to achieve specific mechanical properties, especially for high-temperature service. |
| Hardness Requirements | Maximum hardness is typically specified around 43 HRC for alloy steels. | Varies depending on grade; for example, B7 has a typical maximum hardness of 35 HRC. |
| Surface Finish | Often provided with a plain or black oxide finish; other finishes are available depending on application needs. | Typically supplied with a plain finish; can be hot-dip galvanized, zinc-coated, or otherwise treated for corrosion resistance. |
| Testing and Certification | Requires mechanical property testing, including tensile strength, hardness, and dimensional accuracy. | Requires mechanical testing, including tensile strength, hardness, and often includes pressure testing for bolts in critical applications. |
| Corrosion Resistance | Limited corrosion resistance unless specially coated or treated. | Offers better corrosion resistance, especially in grades like B8 (stainless steel), making it suitable for corrosive environments. |
| Temperature Resistance | Suitable for moderate temperature environments, not specifically designed for extreme temperatures. | Specifically designed for high-temperature applications, withstanding temperatures up to 1100°F (593°C) depending on the grade. |
| Certification Requirements | Requires certification to ensure compliance with ASTM standards for material properties and dimensions. | Must meet rigorous certification requirements, often including traceability and heat treatment records, particularly for critical applications. |
| Common Industries | Widely used in automotive, machinery, and general engineering. | Commonly used in petrochemical, power generation, and chemical processing industries. |
| Availability | Readily available in standard sizes for commercial use. | Available in a wide range of sizes and grades, with some grades being specialty items for critical applications. |
| Cost | Generally lower cost due to simpler production and material requirements. | Higher cost due to specialized material properties, testing, and certification requirements. |
ASTM A574 is ideal for high-strength mechanical fasteners, while ASTM A193 is tailored for high-pressure and high-temperature applications in critical industries.