Stainless Steel CNC Machining
Stainless steel is a ubiquitous metal critical to a myriad of industries from medical to power generation. Its value lies in its strength, heat resistance, and exceptional corrosion resistance. Indeed, the ability to resist corrosion is the primary thing that distinguishes stainless steel from regular steel. Choose from a wide selection of stainless steel materials for CNC machining in the Findtop Instant Quoting Engine℠.
About Stainless Steel for CNC Machining
The main difference between stainless steel and ordinary steel is that stainless steel alloys contain chromium. The chemical composition of all stainless steels contains at least 10.5% chromium. The addition of chromium gives these steels better corrosion resistance. Different grades of stainless steel use different alloying elements to further improve corrosion resistance, plasticity and machinability. It should be noted that heat treatment can significantly affect the mechanical properties of the metal.
Stainless steel can be divided into austenite, steel, martensite and biphase according to its crystal structure.
Stainless Steel At a Glance
| Application | Used in the automotive, consumer goods, aerospace, and medical industries, primarily in applications that require exceptional corrosion resistance. |
| Advantages | Good heat resistance, excellent corrosion resistance, high strength and toughness |
| Disadvantages | Expensive; can be difficult to machine depending on alloy and heat treatment |
| Lead Time | Minimum 3 days; potentially longer for complex or internationally manufactured parts. |
| Price | $$-$$$ |
| Tolerances | Machining tolerances depend on the exact alloy used. However, a tolerance of 0.005” is generally achievable. |
| Wall Thickness | Minimum ~0.03” (0.80 mm); may vary depending on the ratio of wall thickness to planar dimension as well as alloy. |
| Max Part Size | The maximum size of the part is determined by the machines available and the complexity of the part. |
Stainless Steel 15-5
Stainless steel 15-5 is a precipitated carbonization (PH) material. This process gives it outstanding toughness, strength and corrosion resistance. The low temperature heat treatment improves mechanical properties and enables the material to be widely used in aerospace and nuclear applications.
Stainless Steel 15-5 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 1208 | 75 | 9.8 | 420 | 7.8 |
Stainless Steel 17-4
This precipitation-hardened (PH) steel grade has better corrosion-resistant properties at high temperatures when compared to 15-5 stainless steel. It achieves this increased corrosion resistance by sacrificing mechanical strength. This is also one of the more widely used grades of PH stainless steel. Applications include chemical processing parts and gas turbines.
Stainless Steel 17-4 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 1090 | 77.4 | 6 | 352 | 7.70 |
Stainless Steel 18-8
This grade of stainless steel has an austenitic crystal structure and is one of the most widely used grades. 18-8 is often referred to as 304 stainless steel or SS304, and Xometry quotes 18-8 as SS304, but the two have slight differences in some alloying elements. 18-8 has good corrosion resistance characteristics and is regularly used to create fasteners and pressure piping.
Stainless Steel 18-8 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 215 | 74 | 70 | 123 | 8 |
Stainless Steel 303
By incorporating sulfur into the alloy composition, grade 303 austenitic stainless steel is easier to process than SS304. However, this addition makes the alloy less resistant to corrosion than SS304. It is therefore ideal for parts that need to be reworked, such as gears and shafts.
Stainless Steel 303 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 415 | 77.2 | 40 | 228 | 8 |
stainless steel 304
Grade 304 austenitic stainless steel has good corrosion resistance and is widely used in the production of fasteners. It is often seen as a slightly less corrosion-resistant but more expensive alternative to SS316. This alloy is very similar to 18-8 stainless steel, but it has a higher strength due to its higher carbon content. Already
Stainless Steel 304 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 215 | 77 | 70 | 123 | 8 |
Stainless Steel 316
Grade 316 austenitic stainless steel contains molybdenum, giving it top corrosion resistance. In addition, it has excellent reprocessing and weldability. Applications include chemical containers and Marine parts. The 316L low-carbon version is more resistant to chloride corrosion than the basic formula.
Stainless Steel 316 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 290 | 74 | 50 | 217 | 8 |
Stainless Steel 416
416 stainless steel is one of the most easily machined stainless steels. As with other alloys, its processability is improved at the expense of corrosion resistance, so it is usually more prone to rust than other stainless steels. Applications include motor shafts and gears.
Stainless Steel 416 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 600 | 83 | 20 | 237 | 7.8 |
Stainless Steel 420
The Type 420 martensitic stainless steel has more carbon and less chromium than the premise and other steels. Due to the reduction of chromium content, it tends to rust easily, but in the annealed state, its mechanical properties are improved.
Stainless Steel 420 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 345 | 75 | 25 | 241 | 7.8 |
Stainless Steel 440C
440C stainless steel contains the most carbon in the 400 series, which means that 440C has only weak corrosion resistance. However, it has outstanding hardness characteristics (which can be further improved by heat treatment) and high mechanical strength. Typical applications include housing bearings and surgical instruments.
Stainless Steel 440C Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 445 | 83.9 | 14 | 223 | 7.8 |
Stainless Steel 410
The 410 stainless steel is the most versatile steel in the 400 series. Its low carbon content gives it better corrosion resistance. Like other martensitic steels,410 can be quenched to obtain excellent mechanical strength. 410 stainless steel is commonly used in tableware, fasteners and mechanical parts.
Stainless Steel 410 Properties
| Tensile Strength, Yield (MPa) | Fatigue Strength (MPa) | Elongation at Break (%) | Hardness (Brinell) | Density (g/cm^3) |
|---|---|---|---|---|
| 1225 | 73 | 14.5 | 422 | 7.8 |
Finishes and Post-Processing Options
Brass is often uncoated because of its excellent electrical conductivity, corrosion resistance and low coefficient of friction. If the application is in the case of high appearance requirements, you can consider applying a clear coating.
Hand grinding, mechanical polishing or grinding: Brass is often used to make decorative pieces. Part of the reason is that different alloys produce different colors. The polished brass has a very smooth, glossy surface, making it the best choice for visual components
Cost-saving Design Tips
Findtop offers a variety of surface treatments for stainless steel.
Post-machining (standard): This standard treatment keeps the part in its original state after processing. Findtop can achieve surface roughness of 125 Ra or higher. Secondary machining can be performed to further optimize roughness. This is the most common treatment of stainless steel.