Stainless Steel 430L MIM
MIM 430L Introduction
Stainless steel 430L is a low-carbon ferritic stainless steel, it has similar corrosion resistance as nickel stainless steel in mildly environments or atmospheric exposure. It is ferritic steel with major chromium elements, belongs to non-hardenable steel. This grade of stainless steel provides an excellent combination of corrosion resistance and practical mechanical properties.
Stainless steel 430L is ferritiic stainless steel, it has a body-centered cubic crystalline structure. This ferritic structure makes MIM 430L to be magnetic. This fettitic crystal structure also makes 430L become brittle in cryogenic temperature.
Stainless steel specifications:
UNS: ASTM/ASTE S43000
DIN: 1.4016
The normal applications are automatic screw machines, dishwasher linings, lashing wires.
Chemical Composition
The common composition of MIM 430L after sintering is as following:
| Stainless steel 430L | Iron | Silicon | Carbon | Chromium | Phosphorus | Manganese | Sulfur | Niobium |
| Percent by Weight | BaL. | <1.0 | <0.03 | 14.00-18.00 | <0.045 | <1.0 | <0.03 | 0.2-0.5 |
Typical Mechanical Properties
The typical mechanical properties of MIM 430L are as following:
| Physical Properties | Density | Melting Point | Solidus | Liquidus | Maximum Service temperature |
| 430L | 7.75 g/cm3 | 1425-1500℃ | 1425℃ | 1510℃ | 815℃ |
The toughness of ferritic steel is relatively low, its ductile-to-brittle temperature is at or above room temperature. The corrosion and oxidation resistance of ferritic stainless steels are related to the chromium content. Therefore, the 17% Cr content in stainless steel 430L ensure the corrosion resistance in atmospheric conditions. Stainless steel 430L is used in applications with critical corrosion resistance than strength, normally it has excellent resistance in various corrosion media.
Stainless Steel 430L Properties
Stainless steel 430L is ferritic and non-hardenable grade with straight chromium, it combines good corrosion resistance and formability characteristics. Its unique resistance to nitric acid ensures specific chemical applications, while its common application fields are automotive trim and appliance components.
Corrosion Resistance
Stainless steel 430L has excellent resistance to various corrosive environments, including nitric acid and organic acids. This stainless steel can achieve maximum corrosion resistance in high polishing or buffing conditions.
In general, stainless steel 430L has similar resistance to pitting and crevice corrosion as stainless steel 304. In addition, stainless steel 430L has very high cracking resistance of stress corrosion, this is the most common characteristic of all ferritic stainless steel.
Heat Resistance
Stainless steel 430L can resist oxidation in intermittent application up to 870℃, and in continuous application up to 815℃. After prolonged heating in the range of 400 – 600℃, stainless steel 430L will become brittle at room temperature. However, annealing treatment can eliminate this effect.
Heat Treatment of MIM 430L
There is a fact that stainless steel 403L is not hardenable by thermal treatment. Ferritic stainless steels are normally non-hardenable, the hardness of these stainless steels will not increase during quenching process. Therefore, the only applicable heat treatment for this grade is annealing.
Solution Annealing
Heat to 815-845℃, and holding for according time with different thickness. Then slow cool to 600℃ in furnace, and quickly air cool to room temperature. As slow cooling from 540-400℃ temperature will result in embrittlement.
Sub-critical annealing
Heat to 760-815℃, then air cool or water quench to room temperature.
Machining
430L is easier to machine than the standard austenitic stainless steel, such as stainless steel 304. The main reason is high elastic modulus, this grade materials are difficult to stretch or bend.
Elastic modulus describes deformation of material in the applied force, high elastic modulus means less deformation and gummy. As the elastic modulus of stainless steel 430 is 200 GPa, it is higher than 300 series steels.
Machining this grade steel is better in stain-hardened condition with stress. There is less deformation in stress conditions, and easily broken off in pieces. However, in annealed state, the soften structure will result in difficult machining with unexpected burrs. Sintered parts of stainless steel 430L are lightly easier to machine than those in annealed condition
MIM 430L Welding
As-welded stainless steel 430L is not suitable for robust applications, there is embrittlement risk in the heated zone. At elevated temperatures, pitting and crevassing will occur on the surface of 430L.
Properties to Common Fabrication
- Lower hardening rate make it easier to bend and form than stainless steel 304.
- Lower ductility restricts severe post-processing operations.
- Severe bends can reach at right angels to the rolling direction.
Comparison of 430L and 430F
Composition
The comparing composition of MIM 430L and 430F after sintering:
| Grade | C | Mn | Si | P | S | Cr | Ni | |
| 430L | Min. | 0 | 0 | 0 | 0 | 0 | 16.0 | 0 |
| Max. | 0.12 | 1.00 | 1.00 | 0.04 | 0.03 | 18.0 | 0.75 | |
| 430F | Min. | 0 | 0 | 0 | 0 | 0 | 16.0 | – |
| Max. | 0.12 | 1.25 | 1.00 | 0.06 | 0.15 | 18.0 | – | |
Physical Properties
The typical comparing physical properties of MIM 430L and 430F:
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness | |
| HRB | HB | ||||
| 430L | 450 | 200 | 22 | 89 | 183 |
| 430F | 550 | 380 | 25 | – | 262 |
Mechanical Properties
The typical comparing mechanical properties of MIM 430L and 430F:
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness | |
| HRB | HB | ||||
| 430L | 450 | 200 | 22 | 89 | 183 |
| 430F | 550 | 380 | 25 | – | 262 |
Possible Alternative Stainless Steel Grades
There are different alternative stainless steel grades to MIM 430L.
430F: higher mechinability than 430L, lower corrosion resistance.
434: better pitting resistance.
304: slightly higher corrosion resistance, improved welding and cold forming.
316: better corrosion resistance, improved welding and cold forming.
3CR12: cost-critical applications with lower corrosion resistance.
MIM 430L Application
MIM 430L combines low cost with good corrosion resistance, this make it suitable for domestic appliances, such as: Dish washer Liners, Refrigerator Cabinet Panels, Stove Trim Rings, Fastener, Fuel Linings.
In addition, the automotive industry applies stainless steel 430L in decoration and muffler systems. For specific magnetic applications, MIM 430L is the best option with corrosion resistance.
Conclusion
Stainless steel 430L provides good corrosion resistance with soft-magnetic. This makes it suitable for specific applications.
