Stainless steel is one of the most popular materials. Its usability is diverse across different industries. However, Hastelloy is an excellent option that surpasses stainless steel in performance. However, both of these materials differ in many aspects. Their differences bring up a debate on Hastelloy vs stainless steel.
From aerospace to automobiles, these materials dominate everywhere. However, things can be confusing when it comes to choosing any of these materials. That’s where this article will help you by differentiating their key differences. After reading this, you’ll know whether stainless or Hastelloy is best suited for you. So, let’s get going!
Basic Rundown of Hastelloy & Stainless Steel
Let’s first discuss stainless steel material.
Stainless steel is an iron-based alloy that contains chromium, nickel, and many other elements. It has around 70% iron and more than 10.5% chromium. Its composition varies depending on which grade of stainless steel you have. This material offers excellent durability at very affordable prices.
Stainless steel is very popular due to its low pricing. It offers excellent features, making it a replacement for many high-end materials. Stainless steel comes in many grades, such as 304, 316, 430, and so on. Interestingly, both stainless steel and Hastelloy have many similar composition elements. Let’s look at Hastelloy now.
Hastelloy is a brand name for a family of nickel-based alloys. These alloys consist of 57-65% nickel. Other alloy elements used in this include chromium, molybdenum, carbon, manganese, and so on. Its higher nickel and chromium content makes it stand out.
Hastelloy also has grades such as C-276 and C-22. Back in 1913, Harry Brearley first discovered stainless steel. It added 12% of chromium to the steel to see if it increased the strength of the steel. Intestinally, the experiment worked, and it enhanced the corrosion resistance. Interestingly, the Hastelloy alloy was discovered in the same era, i.e., in the 1920s.
However, Haynes International (an American manufacturer) made this material. It is well known due to its specific properties. Those include excellent heat, corrosion, and oxidation resistance. Both of these materials have their pros and cons. Manufacturers use them per their budget and the features they want in the product.
What are the Differences Between Hastelloy & Stainless Steel?
The portion mentioned above gives a brief introduction to these materials. However, the decision about their selection should be made after understanding their differences. In the section below, I’ll discuss all the differences between these two alloys.
1- Chemical Composition & Appearance
The chemical composition of these alloys depends on their grades. However, generally, Hastelloy has nickel as its most prominent element, followed by chromium. On the flip side, stainless steel is an iron-based alloy. It has 70% iron, followed by 10.5 to 30% chromium. The nickel content in stainless steel is just 7 to 10%.
Here is a table showing a detailed comparison of their composition:
| Element | Hastelloy | Stainless Steel |
| Nickel (Ni) | 57-65% | 8-10.5% |
| Chromium (Cr) | 14-17% | 18-20% |
| Molybdenum (Mo) | 15-17% | 0-3% |
| Iron (Fe) | small percentage | 70-75% |
| Manganese (Mn) | 0-1% | 2-2.5% |
| Silicon (Si) | 0-0.5% | 0-1% |
| Carbon (C) | 0.01-0.15% | 0.08% |
| Phosphorus (P) | 0-0.04% | 0-0.045% |
| Sulfur (S) | 0-0.01% | 0-0.03% |
As the table shows, these materials have many similar alloy elements. However, the proportion of each alloy element varies, giving them unique properties. Hastelloy has a dull gray color with a matte and glossy finish. On the other hand, stainless steel has a brighter, shiny, and glossy appearance.
2- Corrosion Resistance & Durability
Both stainless steel and Hastelloy offer excellent corrosion resistance. However, I consider Hastelloy a superior option compared to its counterpart. The reason is that it has a high nickel proportion of around 57 to 65%. This nickel creates a nickel oxide layer on the surface of the material.
It protects the material from rusting. Interestingly, these nickel oxide layers are self-healing. If the coating gets scratched, it can heal itself. Therefore, Hastelloy is suitable for making marine tools and products. These products won’t get rusty in salty water. Remember, the Hastelloy material also resists corrosion when strong acids or alkalis are present.
On the other hand, stainless steel is also rust-resistant. It has more than 10.5% of chromium, which creates a chromium oxide layer. This protects the material from rusting. However, this chromium oxide layer can be destroyed and cannot heal. Once this layer deteriorates, the material becomes more prone to rusting.
3- Weight & Heat Resistance
The Hastelloy has a high proportion of nickel (57 to 65%) and molybdenum (15-17%). Both of these elements are of high density. As a result, they increase Hastelloy’s weight. The density of Hastelloy is 8.9–9.2 g/cm³.
On the flip side, stainless steel has a very low proportion of nickel (8 to 10%) and molybdenum (0-3%). This lower proportion does not add much weight to the stainless steel. The density of this material ranges between 7.9 – 8.0 g/cm 3. Regarding heat resistance, both of these two materials offer excellent performance.
However, Hastelloy is slightly better and can sustain heat up to 1000 degrees Celsius. On the flip side, the stainless steel is not bad and is resistant to temperatures up to 870 degrees Celsius. However, the Hastelloy is preferred for heat exchangers and chemical reactors. Stainless is a suitable option for routine cookware and so on.
4- Weldability & Machinability
Stainless wins the race when the competition comes around the ease of weldability and machinability. Let me explain the logic behind it. The Hastelloy has higher nickel and molybdenum content. These two elements are very hard but are sensitive to heat. During welding, they cause hot cracking on the weld. You’ll have to be very careful.
These cracks are more common when you weld the material and leave the weld for solidification. Moreover, welds made on this material can get pores while cooling. This porosity is bad and weakens the overall joint or weld point. Stainless material is not prone to hot cracking. Its ease of weldability is excellent.
When it comes to machinability, stainless steel is miles ahead of Hastelloy. Remember that Hastelloy has a higher nickel content, which makes it brittle. During machining, this material can break and show brittleness. However, stainless steel can be cut smoothly and does not show brittleness. This is due to its lower nickel and molybdenum content.
5- Strength & Hardness
When it comes to strength, both of these materials go head to head. There are no significant differences. Both are corrosion-resistant and perform well in high-temperature conditions. However, the Hastelloy slightly goes ahead due to its slightly higher heat resistance. This material should be used when you are making products for extreme conditions.
Otherwise, stainless steel is suitable for normal conditions. Regarding hardness, Hastelloy again takes a step ahead. How? Its around 15% molybdenum content enhances its hardness. Due to its greater hardness, Hastelloy is wear—and scratch-resistant.
6- Cost & Applications
Hastelloy is a more expensive material as compared to stainless steel. The reason is that its production requires more advanced tools and special conditions. Moreover, this material consists of nickel, molybdenum, and cobalt. All these metals are expensive and not readily available. All these factors increase the price of this material.
On the flip side, stainless steel mainly consists of iron and chromium. Both of these metals are abundant and readily available at a cheap price. Due to this, stainless prices are generally low, making them very affordable. Regarding application, the Hastelloy material can be used in heavy-duty applications.
Products made with this material can be in acidic or salty water conditions. They won’t get rusty. Moreover, they have higher heat resistance, making them an ideal option for heat exchangers. On the flip side, stainless steel has applications in less extreme conditions. It is widely used to make pipes, sheets, and wire.
Here is the table showing the application comparison of these two materials:
| Hastelloy Uses | Stainless Steel Uses |
| Chemical reactors | Kitchen sinks |
| Acid tanks and pipes | Cookware |
| Heat exchangers | Medical tools |
| Marine valves and pumps | Food equipment |
| Exhaust scrubbers | Railings and stairs |
| Aerospace parts | Car parts |
Which One Should You Choose, Hastelloy or Stainless Steel?
There is no one fit for all when deciding between stainless steel and Hastelloy.
The Hastelloy seems to be a superior option due to certain benefits. It offers excellent rust and heat resistance. Moreover, strength and durability are also second to none. So I recommend you choose these materials. Products made with this material will perform well in all conditions.
However, let’s not skip the second side of the mirror. Hastelloy is a costly material. It costs almost three to four times more than stainless steel. Moreover, its weldability, machinability, and overall weight are also high, which can be drawbacks. If you have a tight budget, I won’t recommend using it.
However, if you have a handsome budget and want high-quality products, this material is best suited for you. Remember, stainless is not a bad option for routine usage. It can be a decent option due to its low pricing and optimal performance. It is suitable for cookware, kitchen sinks etc. However, don’t use it to make heavy-duty products such as heat exchangers.
Frequently Asked Questions
Why use Hastelloy?
You should use Hastelloy because it is excellently resistant to rust and heat. Moreover, it is very durable and strong, with a higher hardness. These features make it less prone to wear and scratches.
Is Hastelloy better than stainless steel?
Yes, I consider Hastelloy a superior option due to its specific properties. Those include better rust resistance and overall strength. Moreover, this material can bear high heat, making it heat resistant.
What are the disadvantages of Hastelloy?
This material has some drawbacks, which are as follows:
- Higher pricing
- Brittle and higher-weight
- Compromise weldability & machinability
Conclusion
Let’s conclude the piece by stating that these materials have unique value propositions. I consider Hastelloy as the superior option. However, stainless steel has all the properties of this material but with lower effectiveness.
For example, stainless steel material is also rust and heat-resistant. But it may not perform as well as Hastelloy does. If your product is mild, I recommend choosing stainless steel material. It will save you some bucks. However, Hastelloy is best suited for professional usage. In this article, I’ve explained everything regarding these two materials.