What is the magnetic difference between 1.4401 and 1.4301 stainless steel?

The magnetic difference between 1.4401 and 1.4301 stainless steel lies primarily in their microstructure and chemical composition, especially the presence of molybdenum (Mo) in 1.4401.

🔍 Quick Comparison: Magnetic Properties

Property	1.4301 (AISI 304)	1.4401 (AISI 316)
Microstructure	Austenitic (non-magnetic in annealed state)	Austenitic (non-magnetic in annealed state)
Magnetic Permeability (Annealed)	~1.02 – 1.1	~1.02 – 1.1
After Cold Working	Becomes slightly magnetic	Becomes less magnetic than 1.4301
Alloying Elements	Cr-Ni	Cr-Ni-Mo (added molybdenum)
Practical Magnetism	More magnetic after forming/welding	Less magnetic in similar conditions

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🧲 Why is 1.4401 Less Magnetic Than 1.4301?

Both are austenitic stainless steels, which means they are essentially non-magnetic in the annealed (solution-treated) condition.

1.4301 (304) tends to become more magnetic after cold working (e.g., forming, bending, or rolling) due to the partial transformation of austenite into martensite.

1.4401 (316) contains molybdenum, which stabilizes the austenitic phase and suppresses the formation of martensite, even after cold working-making it less magnetic than 1.4301 in practice.

This chart illustrates how relative magnetic permeability increases with cold working for both stainless steels:

1.4301 (304) shows a significant rise in magnetism after cold work.

1.4401 (316) remains much less magnetic, even under heavy deformation.

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✅ Key Takeaways

In annealed condition, both 1.4401 and 1.4301 are virtually non-magnetic.

After cold working, 1.4301 becomes noticeably more magnetic, while 1.4401 remains weakly magnetic or nearly non-magnetic.

For applications where low magnetic permeability is critical (e.g. MRI environments, electronic enclosures), 1.4401 (AISI 316) is generally the better choice.