High Strength Stainless Steels

NAS NM15M

A high-manganese austenitic stainless steel, NAS NM15M was developed by Nippon Yakin with a composition of 17Cr-15Mn-4Ni. Providing higher strength than conventional non-magnetic austenitic stainless steels, NAS NM15M does not magnetize even if cold worked with force. Nippon Yakin supplies this product in plate, sheet and strip forms.

  • Image: Coil
    Coil
  • Image: Sheet
    Sheet
  • Image: Plate
    Plate

Designation / Standard

Nippon Yakin Grade ASTM JIS
NAS NM15M ― ―

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Chemical Composition

NAS NM15M

  C Si Mn P S Ni Cr N
Min 0.040 ― 14.00 ― ― 4.00 16.50 0.30
Max 0.090 0.90 15.00 0.045 0.015 4.60 17.50 0.35

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Physical Properties

Specific heat (J/kg･K) 480
Specific resistivity (μΩ･cm) 77
Thermal conductivity (W/m･K) 13.2
Coefficient of thermal expansion (10-6/℃) 30–100℃ 16.0
30–300℃ 17.7
30–500℃ 19.2
30–700℃ 20.3
Young's modulus (MPa) 19.6 x 104
Ferromagnetism None
Melting point (℃) 1375-1410

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Mechanical Properties

NAS NM15M

0.2% proof stress
(N/mm2)		 Tensile strength
(N/mm2)		 Elongation
(%)		 Hardness
(HB)
≥ 390 ≥ 690 ≥ 30 ≤ 240

Examples

  0.2% proof stress
(N/mm2)		 Tensile strength
(N/mm2)		 Elongation
(%)		 Hardness
(HB)
Cold-rolled sheet 461 789 45 211

High-Temperature Strength

  0.2% Yield strength
(N/mm2)		 Tensile strength
(N/mm2)		 Elongation
(%)
Room temp. 411 796 55
100℃ 358 679 57
200℃ 259 619 47
300℃ 231 607 47
400℃ 221 575 47
500℃ 191 534 42
600℃ 187 468 36
700℃ 168 371 28
800℃ 151 269 24
900℃ 90 148 39
1000℃ 34 74 62

Image: High-Temperature, Brief Pull

Work Hardening Properties

Image: Work Hardening Properties

Magnetic Permeability

Even when cold working is applied, there is no variation in the magnetic permeability, and NAS NM15M does not become magnetized.

Image: Magnetic Permeability

Age Hardening Behavior

After cold-rolling, the hardness of NAS NM15M can be raised to between 50 and 70 HV with heat treatment between 300 and 500℃.

Image: Age Hardening Behavior

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Corrosion Resistance

Just as with the standard austenitic stainless steel SUS 304, the corrosion resistance of NAS NM15M remains powerful even after strong cold working.

Evaluation of Pitting Corrosion Resistance

Solution-treated 0.34 V
60% cold-rolled 0.31 V

5% NaCl, 30℃

Weather Resistance in Salt Spray Test

Solution-treated No rusting
60% cold-rolled No rusting

5% NaCl, 35℃ for 7 days

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Heat Treatment

NAS NM15M exhibits an austenite structure similar to austenitic stainless steels, and the heat treatment is similar. The typical heat treatment is as follows:

  • Solution treatment 1050-1150℃ Rapid cooling

Workability

Although NAS NM15M can be worked hot or cold nearly identically to austenitic stainless steels, it should be remembered that NAS NM15M is stronger in both hot and cold working.

Applications

Non-magnetic springs, gaskets, electronic components, and other components where magnetism is not desired.

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