Application of different grades of stainless steel materials 201#, 202#, and 848# in the button industry.
Analysis Report on Stainless Steel Button Materials and Metal Detection Performance
I. Overview of Core Principles
The ability of stainless steel buttons to pass through metal detectors fundamentally depends on the match between the material properties and the detection sensitivity. Metal detectors identify foreign objects by sensing the ferromagnetism and conductivity of metals. The alloy composition of the material (especially the content of nickel, chromium, and manganese) directly affects the stability of its austenitic structure, which in turn determines its magnetic and conductive properties.
Important Note: There is no unified standard for "metal detection grades" in the industry. This term is commonly used by companies to refer to the sensitivity settings on metal detector dials. Higher grades indicate higher sensitivity, enabling the detection of smaller metal foreign objects or materials with weaker metallic properties.
II. Comparative Analysis of Major Stainless Steel Grades
1. 201# Stainless Steel (Also Known as 218#)
Material Characteristics: Lownickel, highmanganese austenitic stainless steel.
Standard Composition: Cr 16–18%, Mn 5.5–7.5%, Ni 3.5–5.5%.
Measured Spectral Data: Cr 12.37%, Mn 16.13%, Ni 1.67%, Fe 68.56%.
Process Features: Manganese is heavily substituted for nickel to reduce costs.
Metallic Properties: Retains weak magnetism; relatively high conductivity.
Metal Detection Performance:
Easily detected by medium to lowsensitivity metal detectors.
Typically passes only grades 3–4 metal detection tests.
Applications: Decorative items, shallowstamped components, and products with low metal detection requirements.
Remarks: Measured composition significantly differs from standard (e.g., lower nickel content). Such materials are sometimes referred to as 218# in factories.
2. 202# Stainless Steel (Also Referred to as Grade 8 Material)
Material Characteristics: An upgraded and optimized version of 201 stainless steel.
Standard Composition: Cr 17–19%, Mn 7.5–10%, Ni 4.0–6.0%.
Measured Spectral Data: V 0.151%, Cr 12.46%, Mn 19.05%, Ni 1.57%, Fe 65.39%, Cu 0.818%, Zn 0.105%.
Optimization Features: Adjusted manganesetonickel ratio to improve austenitic stability.
Metallic Properties: Reduced ferromagnetism; lower conductivity.
Metal Detection Performance:
Generates weaker signals in metal detectors.
Can pass mediumsensitivity metal detection tests (grades 4–6).
Applications: Shallowstamped parts, tableware, etc., with slightly higher corrosion resistance and metal detection requirements.
3. 848# Stainless Steel (Also Known as 204#, 208#)
Material Characteristics: Highgrade heatresistant stainless steel.
Estimated Standard Composition: Cr 23–27%, Ni 19–21%, Si 1.5–2.5%.
Measured Spectral Data: V 0.367%, Cr 16.50%, Ni 4.71%, Mn 15.01%, Fe 61.93%, Cu 0.966%, Zn 0.124%, Mo 0.011%.
Process Advantages: Produced via electric arc furnace with argonoxygen decarburization secondary refining, resulting in low impurities and high purity.
Metallic Properties: Extremely stable austenitic structure; almost no ferromagnetism; weak conductivity.
Metal Detection Performance:
Extremely difficult for metal detectors to detect.
Can pass highsensitivity metal detection tests (grade 8).
Applications: Food contact, precision instruments, medical supplies, and other fields with stringent metal detection requirements.
III. Key Findings and Industry Status
1. Discrepancies Between Actual and Nominal Composition: Spectral data reveal significant differences between the actual composition of materials in circulation and national standards/nominal compositions, particularly with nickel content often lower than claimed.
2. Confusing Material Nomenclature: The same material composition may be assigned different codes across factories (e.g., 201# and 218#). "848#" is more likely an industry colloquial term rather than a standard grade.
3. Impact of Production Processes: Beyond basic composition, smelting processes (e.g., whether secondary refining is employed) significantly affect material purity and final metal detection performance.
4. Advantages of Customized Materials: Customized materials used by specialized button manufacturers (e.g., Asia Button) are optimized for easy stamping and plating, better meeting the specific needs of button production.
IV. Summary and Recommendations
The metal detection performance of stainless steel buttons exhibits a clear gradient across material grades:
LowEnd: 201# (218#) → Passes grades 3–4 metal detection.
MidRange: 202# → Passes grades 4–6 metal detection.
HighEnd: 848# (204#, 208#) → Passes grade 8 metal detection.
Selection Recommendations:
1. Clarify the required metal detection grade for the end product.
2. Verify the actual material composition rather than relying solely on grade names.
3. For highdemand applications, prioritize highnickel, highchromium materials produced with secondary refining processes.
4. Consider customized materials from specialized button manufacturers for their advantages in process adaptability.
Risk Warning: Due to the lack of industry standardization and significant variability in material composition, it is advisable to conduct spectral testing on incoming materials and perform actual metal detection tests for critical projects.
