15-5 PH vs 17-4 PH

15-5 PH vs 17-4 PH Stainless Steel – What’s the Difference

ByAbhishek Modak

Stainless steel is a popular choice for various industrial applications because of its strength, toughness and corrosion resistance properties. Two of the industry’s most commonly used types of stainless steel alloys are 15-5 PH and 17-4 PH. Both of these alloys are precipitation-hardening grades that offer unique properties. In this blog post, we will compare these alloys to help you decide which would be better for your specific application.

Difference Between 15-5 PH and 17-4 PH Stainless Steel

Composition

The composition of a material is a fundamental factor in determining its properties. 15-5 PH is a martensitic precipitation-hardening stainless steel that contains 15% chromium, 5% nickel and 3% copper. It also has small amounts of molybdenum, niobium, and tantalum. 17-4 PH, on the other hand, is an austenitic precipitation-hardening stainless steel that contains 17% chromium, 4% nickel, 3% copper and 0.3% carbon. It also has small amounts of manganese, silicon, phosphorus, sulfur and other elements.

Strength and Toughness

One of the biggest advantages of 15-5 PH is its high strength and toughness. It has a typical tensile strength of 180 ksi and a yield strength of 150 ksi. It also has excellent toughness and resistance to stress corrosion cracking. 17-4 PH, on the other hand, has a slightly higher tensile strength of 190 ksi and a yield strength of 170 ksi. However, it is easier than 15-5 PH and may be more susceptible to stress corrosion cracking.

Corrosion Resistance

Both 15-5 PH and 17-4 PH offer good corrosion resistance properties. However, 17-4 PH has slightly better corrosion resistance due to its higher chromium content. It is particularly resistant to atmospheric, chemical, and petrochemical environments. 15-5 PH also has good corrosion resistance but may be more prone to pitting and crevice corrosion in harsh environments.

Heat Treatment

Both 15-5 PH and 17-4 PH can be heat-treated to enhance their properties. 15-5 PH, in particular, can be heat treated to achieve high strength and toughness. It is usually annealed at a temperature of 1000-1200°F and then aged at a lower temperature to achieve maximum hardness. 17-4 PH, on the other hand, is usually heat-treated at a temperature of 900-1150°F to achieve maximum strength and toughness

Cost and Availability

The cost and availability of both alloys may vary depending on the supplier and location. Generally, 17-4 PH is more widely available and less expensive than 15-5 PH. However, 15-5 PH has unique properties that may make it more suitable for certain applications, making it worth the extra cost.

Conclusion

In summary, 15-5 PH and 17-4 PH are excellent stainless steel alloys with unique properties and advantages. If you require high strength and toughness, 15-5, PH may be the better choice. On the other hand, if you need better corrosion resistance, 17-4 PH may be more suitable. Choosing these two alloys will ultimately depend on your specific application requirements, budget and availability. Consult a trusted supplier to determine which alloy is best for your project.

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