Stainless Steel – Grade 384 (UNS S38400)
For making the correct choice of metal for any application, we require a thorough knowledge of the material to base the choice on. It may include knowledge about properties, composition, and applications. While selecting a particular grade of stainless steel you must know about its properties.
In this article, let us explore grade 384 stainless steel, its chemical composition, applications, and properties.
Let us get on the journey to explore all you need to know about 384 stainless steel
What Is 384 Stainless Steel?
Grade 384 stainless steel is a high-quality stainless steel belonging to the family of 400 series. It is similar to stainless steel grade 410 but has an extra dose of molybdenum, a special element added to increase its strength, and corrosion resistance. Therefore, it becomes much more suitable for applications requiring enduring properties.
AISI 384 Stainless Steel
AISI 384 stainless steel is majorly composed of the following key elements: carbon, manganese, phosphorus, sulfur, silicon, chromium, nickel, and molybdenum. AISI 384 consists of molybdenum that improves its resistance to pitting and crevice corrosion, making it suitable for applications where other common grades are not suitable.
| Element | Content (%) |
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Chromium (Cr) | 15.00–17.00 |
| Nickel (Ni) | 17.00–19.00 |
| Iron (Fe) | Balance |
Physical Properties of Grade 384 Stainless Steel
Stainless steel Grade 384 has a density of 8.00 grams per cubic centimetre, making it quite heavy in proportion to volume. It has a melting point of approximately 1400 degrees Celsius, thus making it highly heat resistant. It also shows high conductivity to both heat and electricity and hence is a good choice for several industries. Besides, Grade 384 stainless steel shows magnetic permeability and gets magnetized easily.
| Property | Value |
| Density | 7.90–8.00 g/cm³ |
| Melting Point | 1400–1450°C |
| Modulus of Elasticity | 193 GPa |
| Magnetic Behavior | Non-magnetic in annealed condition (austenitic) |
Mechanical Properties of Grade 384 Stainless Steel
Grade 384 stainless steel contains a high percentage of carbon making it very strong and hard. This property makes it suitable for any tough work. It shows high tensile strength and yield strength. Its mechanical properties are the reason behind its high demand in sectors like car manufacturing and aeroplane-building.
| Property | Value (Annealed) |
| Tensile Strength | 515 MPa |
| Yield Strength (@strain 0.200%) | 240 MPa |
| Elastic Modulus | 193 GPa |
| Poisson's Ratio | 0.27-0.30 |
| Elongation at break (in 50mm) | 55.00% |
| Hardness, Brinell (converted from Rockwell B hardness) | 123 |
| Hardness, Knoop (converted from Rockwell B hardness) | 138 |
| Hardness, Rockwell B | 70 |
| Hardness, Vickers (converted from Rockwell B hardness) | 129 |
Thermal Properties of Grade 384 Stainless Steel
While we have already discussed the mechanical and physical properties of the stainless steel grade 384, let us now look at its thermal properties.
| Property | Value |
| Thermal Conductivity (at 100°C) | 16.2 W/m·K |
| Electrical Resistivity | ~740 nΩ·m |
| Thermal Expansion (0–100°C) | 17.2 x10⁻⁶/K |
Applications of Grade 384 Stainless Steel
Grade 384 stainless steel because of its magnificent properties is widely used in various applications including:
- Cutlery,
- Surgical instruments,
- General hardware,
- Valve and pump shafts and,
- Parts of the machines,
- Heavy machinery,
- Turbine blades,
- Steam turbine,
- In several applications having high temperatures.
384 vs 304 Stainless Steel: What's the Difference?
| Property | 384 Stainless Steel | 304 Stainless Steel |
| Nickel content | 17.00–19.00% | 8.00–10.50% |
| Work-hardening rate | Lower | Higher |
| Best fit | Severe cold heading, fasteners | General-purpose fabrication |
| Cost | Higher | Lower |
Frequently Asked Questions
Q1. Is 384 stainless steel magnetic?
384 stainless steel is austenitic and is essentially non-magnetic in the annealed condition, the same as other 300-series grades. Cold heading and cold working can introduce slight magnetic permeability, but it does not become strongly magnetic.
Q2. What is 384 stainless steel used for?
384 stainless steel is used mainly for cold-headed fasteners, rivets, and small precision parts, thanks to its low work-hardening rate and high nickel content, which make it easier to cold-form than standard 304.
Q3. Is 384 stainless steel similar to 410 stainless steel?
No. 384 stainless steel is an austenitic grade (UNS S38400), while 410 is a martensitic grade. They belong to different stainless steel families with different corrosion resistance, magnetic behavior, and heat-treatment response. 384 is closer in family to 304 than to 410.
Q4. What is the difference between 384 and 304 stainless steel?
384 stainless steel has a higher nickel content (17.00–19.00%) than 304 (8.00–10.50%), which lowers its work-hardening rate and makes it better suited to severe cold-heading operations used in fastener manufacturing.