Maraging Alloy 350 - Heat Treatable Austenitic/ Martensitic Corrosion Resistant Alloy from Super Alloys

Background

The Super Alloys management team are amongst the most experienced professionals in the market. Supported by professional metallurgists and technicians, Super Alloys not only provide access to the largest range of high-tec metals in Europe, but also access to the broadest range of expertise.

The unique combination of access to stock, expertise and rapid delivery reduces lead times and can eliminate costly production delays.

The Super Alloys range of materials includes:

Maraging Alloy 350

The maraging 350 alloy is a heat treatable austenitic/ martensitic alloy (depending on heat treatment) that brings together the strength of heat treatable martensitic grades with the corrosion resistance of some of the chromium nickel austenitic grades.

Maraging Alloy 350 Industry Standard

Maraging alloy 350 complies with the MIL S-46850 industry standard.

Applications of Maraging Alloy 350

The maraging alloy 350 is use in a wide range of applications including:

  • industrial cutters
  • valve and gas turbine components

Heat Treatment of Maraging Alloy 350

Typically, the alloy 350 precipitation hardening alloy is furnished in the annealed condition (Condition H). In this condition, the material possesses an austenitic structure, although it has several percent delta ferrite. As an austenitic material, alloy 350 precipitation hardening alloy possesses a relatively low strength. This low strength maximizes formability. Heat treatment is used to obtain the high precipitation hardened strength of the alloy. Heat treatments are done to accomplish two necessary steps. The first is a heat treatment, which allows the relatively stable austenite of Condition H to transform to martensite (Austenite Conditioning and Transformation). The second is a precipitation hardening heat treatment to further strengthen the material.

The austenite is easier to transform to martensite using a lower temperature heat treatment. For this reason, Condition DA uses a 1400°F (760°C) heat treatment to produce a martensite transformation around room temperature, and this is followed by a precipitation hardening heat treatment at 1050°F (565°C).

If Condition SCT 850 is desired, the austenite conditioning heat treatment is conducted at about 1700°F (925°C). In this case, the martensite transformation is not complete until the material is held for minimum of 3 hours at -100°F (-73°C). When the transformation is complete, the material is precipitation hardened at 850°F (455°C) for a minimum of 3 hours.

Chemical Composition of Maraging Alloy 350

The Super Alloys heat treatable maraging alloy 350 has the following chemical composition that gives it its unique properties.

Table 1. Chemical composition of maraging alloy 350

Chemical Elements

Min

Max

Nickel

4.0

5.0

Molybdenum

2.5

3.25

Carbon

0.07

0.11

Phosphorus

-

0.04

Sulfur

-

0.03

Silicon

-

0.5

Manganese

-

0.8

Iron

75.0

-

Chromium

16.0

17.0

Nitrogen

0.07

0.13

Mechanical Properties of Maraging Alloy 350

The mechanical properties of maraging alloy 350 following different heat treatments are outlined in the following tables.

Table 2. Mechanical properties of maraging alloy 350 under condition H

1500°F (816°C), 1 hr, AC

Metric

English

Tensile Strength, Ultimate

1035 MPa

150 ksi

Tensile Strength, Yield

480 MPa

70 ksi

Percent Elongation

30 %

Hardness

20 HRc

20 HRc

Table 3. Mechanical properties of maraging alloy 350 under condition SCT 850

900°F (482°C), 4-6hrs, AC

Metric

English

Tensile Strength, Ultimate

1380 MPa

200 ksi

Tensile Strength, Yield

1520 MPa

220 ksi

Percent Elongation

9 %

Hardness

46 HRc

46 HRc

Table 4. Mechanical properties of maraging alloy 350 under condition DA

900°F (482°C), 4-6hrs, AC

Metric

English

Tensile Strength, Ultimate

1100 MPa

160 ksi

Tensile Strength, Yield

1930 MPa

280 ksi

Percent Elongation

10 %

Hardness

42 HRc

42 HRc

Physical Properties of Maraging Alloy 350

The physical properties of maraging alloy 350 are outlined in the following table.

Table 5. Physical properties of maraging alloy 350 under condition H

Metric

English

Thermal Expansion 21°C (70°F)

15.2 µm/m-°C

8.4 µin/in-°F

Thermal Conductivity

15.9 W/m-K

9.2 BTU-in/hr-ft2-°F

Available Product Forms of Alloy 350

Maraging alloy 350 is available in the forms of plate, bar, sheet, tube, billet, and forging

For more information on this source please visit Super Alloys International

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