Cronidur®30 is a familiar name in the aerospace industry. The steel has high hardness and corrosion resistance, making it an ideal grade for components in demanding applications. Aerospace Materials Specification (AMS) 5898 calls for a steel of Cronidur®30’s composition. However, it’s not always easy to source Cronidur®30 in the United States. The good news is that an alternative alloy is available through Sullivan Steel—XD15NW®.
This post describes the properties and performance of these two premium aircraft-quality steel alloys to demonstrate that, in most applications, XD15NW® may be a viable alternative to Cronidur®30.
Chemical Properties
XD15NW® (X40CrMoVN16-2) and Cronidur®30 (X30CrMoN15) are CREN (corrosion resistant nitrogen) steels. They have a high nitrogen content and comparatively low carbon, which means both metals exhibit higher corrosion resistance compared to grades such as 440C. Below is a table showing the composition of Cronidur®30 and XD15NW®.
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XD15NW® |
1.4123 - AMS 5925 |
ESR |
0.37-0.45 |
0.00-0.60 |
0.00-0.60 |
15.00 - 16.50 |
1.50-1.90 |
0.20-0.40 |
0.16-0.25 |
0.00-0.30 |
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Cronidur®30 |
AMS 5898 |
PESR |
0.28-0.34 |
0.30 - 0.80 |
0.30-0.60 |
14.50 - 16.00 |
0.95-1.10 |
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0.35-0.44 |
0.00-0.30 |
There is a difference in the manufacturing processes for the two alloys. Both grades are air melted and then the ingots are processed with an electro-slag remelt (ESR) furnace. Cronidur®30 uses a pressurized ESR, while XD15NW® uses a standard ESR. The pressurized ESR helps Cronidur®30 achieve a slightly higher percentage of nitrogen.
Performance
XD15NW® is a Cronidur®30 alternative. In aerospace applications, both metals can be used in high-temperature, high-pressure environments where failure is not an option. They offer a hardness not lower than 58 HRC with extremely good corrosion resistance—a difficult combination for a steel alloy to achieve.
This table shows the properties of the two alloys after comparable heat treatments.
Metric
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Grades / Designation |
Heat |
UTS |
0.2% YS |
KV |
K1c |
HRC |
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XD15NW® AMS 5925 |
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1825 |
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Cronidur®30 AMS 5898 |
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Imperial
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Grades/ |
Heat |
UTS |
0.2% YS |
KV |
K1c |
HRC |
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XD15NW® X40CrMoVN16-2 1.4123 AMS 5925 |
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Cronidur®30 |
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Fatigue
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Heat Treatment
Cronidur®30 and XD15NW® both have crystalline molecular structures that make them very hard and resistant to fatigue and crack propagation. They are both martensitic steels that can accept several types of heat treatment to optimize their properties for the given application.
The temperatures and processes for heat treatment and hardening are similar for Cronidur®30 and XD15NW®. You can use the same heat treat source, same machining setup, and will encounter the same minimal distortions during the heat treat process.
The experts at Sullivan Steel will provide you with the documentation and advice needed to properly process XD15NW® to achieve peak performance with this alloy.
Applications
With their hardness and corrosion resistance, Cronidur®30 and XD15NW® are both used for components subject to high stress. Applications include aerospace, chemical, food processing, and the medical and pharmaceutical industries.
Cronidur®30 and XD15NW® are typically used for bearings, ball-screws and roller-screws, as well as rod ends, spindles, and industrial knives.
Specifications: AMS 5898 vs. AMS 5925
You may have a part that specifically cites Aircraft Materials Specification (AMS) 5898. However, if you cannot source Cronidur®30, or would prefer to have a second source for supply-chain security, it’s time to investigate AMS 5925.
AMS 5925 is comparable to AMS 5898, with nearly identical performance results. For many existing critical air and space parts, AMS 5898 and AMS 5925 may be dual qualified, which means there’s an opportunity to use either alloy to manufacture the part.
XD15NW® meets AMS 5925, as well as Boeing BMS 7-357 and ASTMF899.XD15NW® – An Alternative to Cronidur®30
Cronidur®30 combines the high hardness and corrosion resistance needed for extreme applications, such as aerospace bearing components. But at times it may be difficult to get.
If you’re having trouble finding a reliable source of Cronidur®30, or you’re looking for options to strengthen your supply chain, consider XD15NW®:
- Comparable performance to Cronidur®30, N360
- HRC of at least 58 after tempering at low (around 180°C/360°F) or high (500°C/932°F) temperatures
- Significantly better corrosion resistance compared to 440C (X105CrMo17)
- Low residual austenite after heat treatment to ensure high dimensional stability of parts
- Heat treatment is relatively simple, utilizing standard equipment
- Meets AMS 5925 with comparable performance to AMS 5898
Sullivan Steel’s engineers and metallurgists fully support the steel we sell. We’ve helped numerous customers switch from Cronidur®30 to XD15NW®—you can depend on our experts to help you every step of the way before, during, and after a purchase.
