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Stainless Steels - Identification Tests

Magnetic, spark, hardness and acid identification tests for austenitic, martensitic and ferritic stainless steels.

Stainless steels can be hard to identify. The different types can be distinguished by methods as

  • magnet testing
  • spark testing
  • hardness testing
  • acid testing

For full table with Sulfuric and Hydrochloric Acid Test - rotate the screen!

Stainless Steels - Identification Tests
AISI TypeGradeGroupMagnet TestSpark TestHardness TestSulfuric Acid TestHydrochloric Acid Test
302 Chromium-
Austenitic Non-
Few forks - short, reddish >165 Brinell after heated to 1800oF and water quench Strong attack - green crystals and dark surface Rapid reaction - pale blue-green solution
303 Spoiled egg odor - heavy black smudge
303Se Garlic odor
304 Strong attack - green crystals and dark surface Fast attack - gas formation
308 Full red without many forks
316 Few forks - short, reddish Slow attack - tan surface turns brown Very slow attack
321 Fast attack - gas formation
410 Chromium Martensitic Magnetic Long white with few forks > 280 Brinell after heated to 1800oF and water quench Rapid reaction - dark green solution
416 Spoiled egg odor - heavy black smudge
416Se Garlic odor
420 Long white-red with burst
431 Long white with few forks
440 A, B, C Long white-red with burst
430 Ferritic Long white with few forks 180 - 250 Brinell after heated to 1800oF and water quench
430F Spoiled egg odor - heavy black smudge
430FSe Garlic odor
446 Full red without many forks

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