Do you know the melting point of stainless steel? You might assume the answer is a precise number, but in reality, stainless steel has a melting point range. Understanding this range is crucial for foundries and engineering firms, as it determines how materials are cast, welded, and heat-treated. This article provides a comprehensive overview of stainless steel’s melting point, helping you select the appropriate casting materials and optimize processing steps.
What is the Melting Point
The melting point is the temperature at which a metal changes from a solid to a liquid state under standard atmospheric pressure. During melting, a solid-liquid phase transition occurs within the metal.
Understanding a metal’s melting point is crucial in manufacturing and engineering. It provides essential guidance for welding, casting, and heat treatment processes, while also enabling engineers to ensure materials perform optimally and predict their service life. Additionally, knowing a metal’s melting point helps you select suitable materials for specific applications, such as high-temperature environments.
What is the Melting Point of Stainless Steel
Stainless steel is a type of steel alloy. Unlike pure metals, alloys do not have a precise melting point; instead, they typically have a “melting range,” which is crucial for casting. With over a hundred grades of stainless steel, each grade possesses a distinct melting point due to subtle
variations in its composition. Generally speaking, the melting point of stainless steel ranges between 1400 and 1530°C (2550 to 2790°F).
Melting Points Of Common Stainless Steel
Due to differences in the constituent elements and their respective contents across various stainless steel grades, their melting points also vary.
Among the five major categories of stainless steel, ferritic stainless steel typically possesses the highest melting point, followed by martensitic stainless steel. Precipitation-hardening stainless steel occupies the middle range, followed by duplex stainless steel, with the most widely used austenitic stainless steel having the lowest melting point.
Below are the melting points of common industrial stainless steel grades.
| Category | Grade | Melting Point Range °C | Melting Point Range °F | Notes |
|---|---|---|---|---|
| Ferritic Stainless Steel | 430 | 1425 – 1510 °C | 2600 – 2750 °F | It has the highest melting point and good fluidity, but care must be taken to avoid coarse-grain formation during casting. |
| 409 | 1450 – 1530 °C | 2642 – 2786 °F | Common stainless steel grades used for automotive exhaust pipes exhibit good heat resistance. | |
| Martensitic Stainless Steel | 410 | 1480 – 1530 °C | 2700 – 2790 °F | Low-carbon martensitic stainless steel has a melting point very close to that of pure iron. |
| 420 | 1450 – 1510 °C | 2642 – 2750 °F | It has a relatively high carbon content and a melting point slightly below 410. | |
| PH Stainless Steel | 17-4 PH (630) | 1400 – 1440 °C | 2550 – 2625 °F | The most commonly used PH steel in investment casting has a moderate melting point. |
| 15-5 PH | 1400 – 1440 °C | 2550 – 2625 °F | Similar to 17-4PH, the two also exhibit comparable fluidity. | |
| Duplex Stainless Steel | 2205 (S31803) | 1350 – 1460 °C | 2460 – 2660 °F | The wide melting point range and narrow solidification interval make it prone to cracking during the casting process. |
| 2507 (Super Duplex) | 1350 – 1460 °C | 2460 – 2660 °F | Excellent mechanical properties at room temperature. | |
| Austenitic Stainless Steel | 304 (CF8) | 1400 – 1450 °C | 2552 – 2642 °F | An industrial “jack-of-all-trades” with a relatively low melting point. |
| 316 (CF8M) | 1375 – 1400 °C | 2507 – 2552 °F | The addition of molybdenum (Mo) results in a lower melting point than 304. | |
| 310S | 1400 – 1450 °C | 2552 – 2642 °F | Although it is an austenitic stainless steel, it is specifically designed for high-temperature applications (high chromium-nickel). |
Methods for Determining the Melting Point of Stainless Steel
Accurate measurement of stainless steel’s melting point helps ensure it is processed within safe temperature ranges during casting, welding, and heat treatment, reducing the risk of defects. Below are commonly used methods for measuring alloy melting points.
Differential Scanning Calorimetry (DSC)
This method measures the heat absorbed or released by stainless steel during heating and displays it on a DSC graph. A distinct peak appears on the graph when stainless steel undergoes a solid-liquid phase transition (begins melting). This highly accurate method is suitable for various metals.
Thermocouple Method
A temperature sensor is placed in contact with the metal surface to monitor temperature changes in real time. The melting point is determined based on the state of the stainless steel. This method is suitable for the rapid determination of material melting points in industrial settings.
Capillary Method
Stainless steel powder is loaded into a capillary tube and heated at a constant rate while recording data in real time. Researchers take the average temperature between the onset of melting and complete melting as the melting point. This method is simple to operate but offers lower precision.
Melting Point of Stainless Steel vs. Maximum Operating Temperature
Now that we understand the melting points of major stainless steel grades and the methods for determining them, you might wonder whether stainless steel can function normally in environments below its melting point. In other words, can stainless steel withstand high-temperature conditions close to its melting point? Unfortunately, the answer is no. Take 304 stainless steel as an example. Although its melting point reaches 1400°C or higher, its recommended operating temperature is only 870°C. Why is this?
We know that the melting point represents the physical limit at which a material transitions from solid to liquid. However, the maximum operating temperature signifies the performance limit at which a material can maintain structural integrity and corrosion resistance under load. If stainless steel operates in excessively high-temperature environments, the following issues arise:
Dramatic Decline in Mechanical Strength
As the temperature rises, stainless steel’s strength decreases linearly or even exponentially. For instance, 304 stainless steel has a yield strength of approximately 205 MPa at room temperature. At 870°C, its yield strength may drop to just 10-15% of that value, or even lower. If the product still needs to withstand external or internal pressure under these conditions, it may deform or fracture immediately.
Creep Phenomenon
This is the hidden killer of material failure at high temperatures. For stainless steel, creep becomes the primary cause of failure when ambient temperatures exceed 540°C (1000°F). Even if the stress applied to the stainless steel is below its yield strength, it will slowly undergo permanent deformation over time—possibly elongating or gradually thinning until it ultimately fractures.
Reduced Corrosion Resistance
We know stainless steel’s corrosion resistance primarily stems from its surface chromium oxide protective layer. However, at high temperatures, this passivation layer breaks down. For 304 stainless steel, when temperatures exceed 870°C (1550°F), the surface oxide layer thickens, cracks, and eventually peels off. Without the oxide film’s protection, stainless steel begins a new cycle of oxidation in hot air until the oxide layer peels off again. This cycle causes the material’s cross-section to rapidly thin until failure occurs.
Intergranular Corrosion
Although it is renowned for its exceptional corrosion resistance, stainless steel can still rust, perhaps unexpectedly. Between 425°C and 860°C, carbon reacts with chromium within the steel, causing precipitation. This creates “chromium-depleted zones” that not only significantly reduce corrosion resistance but also lead to embrittlement of the stainless steel.
Factors Influencing the Melting Point of Stainless Steel
From the above, we can see that different grades of stainless steel have varying melting points. So what factors influence the melting point of stainless steel? I will now explain.
Chemical Composition
This is the fundamental factor determining stainless steel’s melting point. Stainless steel is an iron-based alloy containing elements such as chromium, nickel, molybdenum, carbon, and silicon. Pure iron melts at 1538°C, chromium at 1890°C, and nickel at 1453°C. Therefore, adding carbon, nickel, and molybdenum lowers the material’s melting point. Chromium, however, increases the melting point of stainless steel—the higher the chromium content, the higher the melting point.
Crystal Structure
The combination of different elements determines the crystal structure of stainless steel, which explains why various types exhibit different melting points. For instance, the face-centered cubic (FCC) structure of austenitic stainless steel features tightly packed atoms, resulting in a lower melting point. Conversely, the body-centered cubic (BCC) structure of ferritic stainless steel has a more loosely packed atomic arrangement, leading to a higher melting point.
Impurities
Impurities represent a potential factor affecting stainless steel melting points. Trace elements like sulfur and phosphorus do not directly impact the overall melting point. However, they tend to accumulate at grain boundaries, forming low-melting eutectics. During heating, these areas reach the melting point first, potentially causing defects like cracks during casting. Thus, the melting point also reflects the material’s purity.
Homogeneity & Segregation
During casting, inadequate stirring of the molten metal or excessive cooling rates may cause compositional inhomogeneity in castings. In practical applications, components with lower melting points may fail prematurely. High-quality investment casting processes effectively mitigate this risk.
Environmental Factors
Environmental conditions (such as atmospheric pressure) can also influence stainless steel’s melting point. While this factor is negligible during casting, it must be considered if your project involves specialized environments like aerospace or deep-sea applications.
Comparison of Melting Points of Stainless Steel and Other Metals
We have already covered the melting point of stainless steel, and I believe you may be interested in learning about the melting points of other metals. The table below lists the melting points of common metals for your reference.
| Metal | Melting Point (°C) | Melting Point (°F) |
| Tin (Sn) | 232°C | 450°F |
| Lead (Pb) | 327°C | 621°F |
| Zinc (Zn) | 419°C | 787°F |
| Aluminum (Al) | 660°C | 1,221°F |
| Bronze (Alloy) | ~700-900℃ | ~1292-1492℉ |
| Brass (Alloy) | ~900–940°C | ~1,650–1,725°F |
| Silver (Ag) | 961°C | 1,763°F |
| Gold (Au) | 1,064°C | 1,948°F |
| Copper (Cu) | 1085°C | 1984°F |
| Cast Iron (Alloy) | ~1,150–1,200°C | ~2,100–2,200°F |
| Carbon Steel (Alloy) | ~1370-1510℃ | ~2498-2750℉ |
| Iron (Fe) | 1538℃ | 2800℉ |
| Titanium (Ti) | 1,668°C | 3,034°F |
| Tungsten (W) | 3,422°C | 6,192°F |
| Nickel (Ni) | 1,453°C | 2,647°F |
From the table above, we can see that stainless steel has a relatively high melting point among metals. While this increases its casting difficulty, it also makes stainless steel commonly used in many high-temperature applications, including heat exchangers and piping systems.
Selecting the Right Stainless Steel for Your High-Temperature Applications
When selecting the appropriate stainless steel casting material for your high-temperature projects, while the melting point is an important reference factor, it should not be the sole consideration. As mentioned earlier, the maximum operating temperature of stainless steel is crucial.
For instance, although austenitic stainless steel has a lower melting point, its creep resistance and oxidation resistance at high temperatures outperform those of ferritic stainless steel with higher melting points. 304 stainless steel castings and 316 stainless steel castings are widely used in heat exchangers and reactors due to their outstanding heat resistance.
However, ferritic stainless steels possess a lower thermal expansion coefficient and superior thermal conductivity compared to austenitic stainless steels. This means they are less prone to fatigue cracking during repeated heating cycles. Consequently, ferritic stainless steel castings, such as grades 430 and 409, are commonly employed in components like automotive exhaust manifolds.
In aerospace applications, components like jet engine turbine blades endure extreme temperatures and stresses, demanding both heat resistance and strength. Here, 17-4PH stainless steel castings provide an ideal solution.
It is crucial to note that while duplex stainless steel offers exceptional corrosion resistance, it must never be used in environments exceeding 300°C (571°F). At such temperatures, it rapidly embrittles, becoming as fragile as glass.
How the Melting Point of Metals Affects the Investment Casting Process
Not only for stainless steel, but the melting point of metals is critically important in investment casting processes, as it dictates how the process operates.
Casting Process
First, the melting point of the metal determines the pouring temperature during casting, which in turn affects the metal’s fluidity and cooling rate. For stainless steel castings, pouring temperatures that are too high or too low can lead to casting defects such as porosity and shrinkage.
Heat Treatment
The melting point sets the maximum temperature limit for heat treatment processes. For instance, the heat treatment temperature (solution treatment) for austenitic stainless steel is typically controlled between 1000°C and 1150°C—well below its melting point—to provide a safety margin for processing. The melting point also influences the specific heat treatment method that should be employed.
Welding
Welding is the most common method for joining metals, and the melting point directly determines welding effectiveness. Before welding, the melting point of the filler material must be significantly lower than the base metal’s melting point to ensure the integrity of the base material. Additionally, the appropriate welding process must be selected based on the metal’s melting point. For example, low-melting-point materials can utilize low-temperature processes like reflow soldering to minimize thermal damage.
When joining metals with vastly different melting points, selecting a filler metal with an intermediate melting point can enhance joint toughness. For instance, when welding high-melting-point high-carbon steel to low-melting-point low-carbon steel, using nickel-based filler wire effectively prevents defects like cracks or porosity.
Conclusion
The above covers all essential knowledge regarding the melting point of stainless steel, and we trust you now have a solid understanding of this material. If you plan to utilize stainless steel for your casting projects, choose us—Pingheng Machinery—to provide you with comprehensive one-stop services. With extensive experience in investment casting and state-of-the-art quality inspection equipment, we deliver high-quality castings that meet your exacting standards. Should you have any casting requirements, please feel free to contact us at any time. We look forward to hearing from you.
FAQ
Q1. What is the burning temperature of stainless steel?
Under normal circumstances, stainless steel does not burn. Its melting point ranges from approximately 1370°C to 1530°C (2500°F to 2785°F), far exceeding the temperatures of common fire sources. However, in oxygen-rich environments (such as laser cutting), stainless steel may ignite due to oxidation reactions, though such scenarios are extremely rare.
Q2. Which stainless steel grade has the highest melting point?
Generally speaking, ferritic and martensitic stainless steels have the highest melting points. They contain relatively low amounts of nickel, with melting points ranging from approximately 1425°C to 1510°C (2600°F to 2750°F), commonly found in the 400 series.
Q3. What is the melting point of 304 vs. 316 stainless steel?
The melting point of 304 stainless steel is slightly higher than that of 316 stainless steel. The chromium content in 316 stainless steel slightly lowers the metal’s melting point. The melting point of 304 stainless steel ranges from approximately 1400°C to 1450°C (2552°F to 2642°F), while that of 316 stainless steel is approximately 1375°C to 1400°C (2507°F to 2552°F).
Q4. Is the melting point of stainless steel higher than that of carbon steel?
In fact, the melting point of carbon steel is slightly higher than that of stainless steel. Stainless steel contains a high amount of chromium and a slight amount of nickel, which lowers the melting point of stainless steel.
Q5. Melting point of titanium vs stainless steel, which is higher?
Titanium has a melting point approximately 200 degrees higher than stainless steel. However, due to its highly reactive chemical properties, it demands stricter casting environment requirements.
Q6. What happens if you overheat stainless steel during casting?
When the heating temperature exceeds the melting point of stainless steel by 50-100°C, it may cause internal porosity in castings and produce a rough surface texture. Furthermore, the structure of the casting may be compromised by high temperatures, thereby reducing its mechanical strength and hardness.
Q7. How does the melting point impact the cost of stainless steel casting?
Due to stainless steel’s high melting point, its energy consumption during casting is also higher. Furthermore, melting and casting high-melting-point stainless steel requires the use of high-temperature-resistant equipment that necessitates regular maintenance, further increasing capital investment. Additionally, the high melting point results in poor fluidity during casting, particularly when the steel contains high-melting-point elements such as chromium (melting point: 1890°C). This necessitates stricter control measures or even more complex processes, both of which elevate the cost of stainless steel casting.
Q8. Can stainless steel be cast into aluminum molds?
No, stainless steel cannot be directly poured into aluminum molds. Because the melting point of stainless steel (~1400°C) is significantly higher than that of aluminum (~660°C), the aluminum would rapidly melt, potentially causing safety incidents.
