17-4 PH Stainless Steel: A Machining Guide on Process

Stainless steel is a versatile CNC machining material with diverse applications across several industries. The 17-4 PH stainless steel grade is the preferred alloy of stainless steel due to its remarkable blend of properties that allow manufacturers and product designers to elevate their products with the desired strength and resistance to corrosion.

This article explores 17-4 PH Stainless Steel, including its properties, advantages, and applications. Let’s get to it!

Contents
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I
What is 17-4 Stainless Steel?

II
What is 17-4 PH Stainless Steel?

III
17-4 Stainless Steel vs. 17-4 PH Stainless Steel

IV
Properties of 17-4 PH Stainless Steel

V
Different Stock Shapes for 17-4 PH Stainless Steel

VI
Processes Used in Machining 17-4 PH Stainless Steel

VII
Advantages of Using Stainless Steel 17-4 PH for Your Projects

VIII
Applications of 17-4 PH Stainless Steel Parts

IX
WayKen CNC Metal Services for Stainless Steel Parts

X
Conclusions

XI
FAQs

What is 17-4 Stainless Steel?

First, let’s know what is 17-4SS. 17-4 stainless steel is a widely embraced stainless steel alloy with about 17% chromium, 3-5% copper, 4% nickel, and other elements like manganese and silicon. This martensic metal alloy offers outstanding corrosion resistance and the ability to maintain its ductility at high temperatures.

In addition, 17-4SS is a cost-effective alternative to high-strength carbon steel due to its excellent corrosion resistance, strength, and fabrication ease. Depending on the required shape and properties, you can make 17-4 alloy parts using processes such as cold working, hot forging, machining, or welding.

What is 17-4 PH Stainless Steel?

So, what is 17-4PH SS? The 17-4 PH stainless steel is a popular precipitation-hardening grade of stainless steel. It is the hardened 17-4 alloy variant, offering greater strength and hardness than the basic alloy. Unlike 17-4 alloy, the stainless steel 17-4PH is heat-treated to achieve the desired hardness and strength, making it a highly versatile metal.

This nickel-chromium grade of stainless steel is more cost economical than most high nickel non-ferrous alloys. The 17-4 PH stainless steel’s valuable properties offer product manufacturers reliability, making the alloy an ideal solution for many design challenges.

17-4 Stainless Steel vs. 17-4 PH Stainless Steel

Although the 17-4 stainless steel properties and 17-4 PH stainless steel are similar, they differ in certain ways. The precipitation hardening (PH) subjects the 17-4 alloy to heat treatment to enhance its yield strength and corrosion resistance. The 17-4 PH stainless steel is a widely used martensitic PH stainless steel that transforms into a solid steel crystalline structure (martensite) at low temperatures of 250ºC.

17-4 stainless steel and 17-4 PH stainless steel contain similar primary elements, but the Columbium (Niobium, Cb) content strengthens the 17-4 PH. Therefore, precipitation hardening of 17-4 stainless steel offers an outstanding combination of corrosion resistance, hardness, and high strength.

In addition, the 17-4 PH stainless steel exhibits higher elongation and excellent tensile and yield strength, making it ideal for high-strength applications such as chemical processing equipment, aerospace components, and firearms. Although the 17-4 PH SS may cost more than stainless steel 17-4SS, its higher cost may be worth certain applications with higher toughness and strength demand.

Properties of 17-4 PH Stainless Steel

The high-alloy 17-4PH stainless steel offers several benefits due to its impressive material properties. Below are its composition and key properties.

Composition

The 17-4 PH SS has a remarkable chemical composition that offers desirable characteristics. It contains elements such as Chromium (CR) 15 – 17.5 %, Nickel (Ni) 3 – 5%, Copper (Cu) 3 – 3.5%, Manganese (Mn) 1% max, Silicon (Si) 1% max, Columbium (Cb) 0.15 – 0.45%, Phosphorous (P) 0.04% max, Sulfur (S) 0.03% max, Carbon (C) 0.07% max, Nitrogen (N) 0.10% max.

Mechanical Properties

The stainless steel 17-4PH exhibits remarkable mechanical properties well-suited for applications that require high strength, hardness, and resistance to corrosive attacks. Its tensile strength ranges from 200-225 ksi, while its yield strength ranges from 175-200 ksi. The hardness of the 17-4 PH SS ranges from 35-45 HRC.

Physical Properties

Stainless steel 17-4PH has a dull appearance in its annealed condition, while it exhibits a bright or glossy finish after heat treatment. This alloy has excellent physical properties like good corrosion resistance, high strength-to-weight, and good electrical conductivity. Also, the 17-4 PH is magnetic, like most martensitic alloys.

Thermal Properties

The thermal properties of the 17-4 PH SS are beneficial in different applications. This alloy has a melting point ranging from 2550 to 2650 ºF (1399 – 1454 ºC). Also, it has a heat capacity of about 460 J/(kg. K) and good thermal stability, allowing it to retain its structural integrity when subjected to elevated temperatures.

Corrosion Resistance

The 17-4 PH SS provides superior corrosion resistance and has high usage in applications requiring moderate corrosion resistance and greater strength. The stainless steel 17-4PH resists corrosion better in food, petroleum, paper, dairy, and chemical applications.

Heat Treatment

The 17-4 PH SS comes in the solution-annealed condition at 1900ºF and air-cooled to 90 ºF. However, subsequent age-hardening treatments help to alter the mechanical properties of this stainless steel type to the required toughness and hardness levels. Typical aging treatments include Conditions H900, H925, H1025, H1075, H1100, H1150, H1150 + 1150, and H1150-M.

Weldability

17-4 PH SS exhibits remarkable welding characteristics among its alternatives. Besides, you can weld this alloy with standard processes, including shielded metal arc, gas tungsten arc, plasma arc, and gas metal arc. However, it is advisable to consider pre- and post-weld heat treatments to achieve preferred mechanical properties.

Different Stock Shapes for 17-4 PH Stainless Steel

Stainless Steel stock materials are often available in different shapes. As we know, a product’s required size and shape determine the ideal stock shape for a machining project. Below are the different shapes 17-4 PH stainless steel is available in:

• Rods
• T-Bar
• Flat Bar
• Round Bar
• Hex Bar
• Square Bar
• Triangle Bar
• Hollow Bar
• Threaded Bar
• Pump Shaft
• Boat Shaft

Processes Used in Machining 17-4 PH Stainless Steel

There are different machining techniques for manufacturing 17-4 PH stainless steel. Here are some of them:

CNC Milling

Milling is a suitable metal fabrication technique for cutting 17-4 PH stainless steel into desired shapes and dimensions. CNC milling machines use a rotating multipoint cutting tool to cut workpieces in a controlled manner. The workpiece engages the milling tool instead of the tool cutter coming to the machined workpiece.

The machining spindle possesses various cutting tools capable of traveling in X, Y, and Z axes to achieve complex designs. This efficient subtractive process offers the preferred machining tolerances when making stainless steel parts.

CNC Turning

CNC turning is suitable for machining parts with cylindrical shapes from 17-4 PH stainless steel. The process employs carbide or coated carbide inserts in machining stainless steel. The cutting tool remains stationary while the stainless steel workpiece is fastened to a mandrel or rotating plate. The cutting tool engages the workpiece to remove excess material as it turns, forming the desired shape and size. Therefore, turning is an ideal method for making volume stainless steel machined parts.

CNC Drilling

CNC drilling is an ideal machining process for making holes in 17-4 PH SS despite its hardness. You might want to use specialized drill bits to make holes in your stainless steel for accurate results. Also, it is advisable to use peck drilling to remove chips and avoid work hardening. CNC drilling stainless steel 17-4 can be economical since it offers precise holes with accurate diameters.

Electrical Discharge Machining (EDM)

EDM or spark machining is a versatile technique that uses repeated electrical current or thermal energy instead of mechanical force to cut through materials such as 17-4 PH stainless steel. Although this technique may be a bit slow, it offers high precision in metal machining. It is perfect for machining small and delicate stainless steel components with complex profiles since it doesn’t use mechanical force in cutting materials.

Advantages of Using Stainless Steel 17-4 PH for Your Projects

The stainless steel 17-4ph offers different benefits across various industries.

Cost-Effectiveness

The 17-4PH stainless steel is affordable for several industrial applications, even though there may be other alternatives with high chromium content. Manufacturers and product engineers often choose stainless steel 17-4PH above alternatives that offer similar strength and corrosion resistance properties since it is the cost-effective option.

Durable

Most applications often require materials such as the 17-4 PH that won’t degrade and stop working over a short period. For instance, engineers often use materials that require less maintenance and repairs for aerospace parts and refining equipment. However, 17-4 PH SS parts are usually long-lasting and fend off corrosion.

High Corrosion Resistance

17-4PH stainless steel offers exceptional corrosion resistance in applications that expose machined stainless steel parts to extremely corrosive substances like mild acids, organic compounds, fresh water, and atmospheric conditions. The chromium content of the 17-4PH SS protects it from oxidation and degradation.

High Hardness and Strength

The 17-4 PH alloy has excellent hardness and strength properties, making it a perfect material for high-stress applications. You can heat-treat the alloy through precipitation hardening to achieve different strength levels, usually between 1100 to 1700 Mpa. The remarkable strength-to-weight ratio of this ally makes it a perfect choice for structural parts, aerospace components, and tooling applications.

Applications of 17-4 PH Stainless Steel Parts

The stainless steel 17-4ph is a versatile metal with outstanding properties required in various applications. Here are some of these typical applications.

Aerospace

Stainless steel is a primary material for creating different aircraft parts and components. The 17-4 PH SS material offers good tensile strength and excellent stress corrosion resistance, which are crucial requirements when producing aerospace equipment. Moreover, it is critical that these parts and components perform well in different temperatures and environments. Therefore, 17-4 PH is the ideal metal for the aerospace sector.

Marine Vessels

The 17-4 PH SS exhibits high mechanical strength and superior resistance to corrosion required in marine applications. Its ability to resist corrosion ensures its survival in salty seawater. The high concentration of chromium element in its composition makes the 17-4 PH stainless steel highly resistant to corrosive substances. Hence, it is well-suited for making vessel pump and valve components. Also, other components such as heat exchangers, seawater, and process piping are made with 17-4 PH.

Oil and Gas Industry

This alloy has the high strength required in making pipes for extracting oil at great depths below sea level. In addition, the 17-4 PH alloy is more corrosion-resistant in different environments. As such, it is suitable for making pipes and oil rigs in this industry since it can withstand corrosive media such as carbon dioxide, hydrogen sulfide gas, and low pH levels in oil prospecting conditions.

Food Processing Equipment

Most of the equipment used in the food processing industry is made from steel. The stainless steel 17-4ph is ideal for making food and beverage processing equipment because of its good surface condition and fine finish.

The smooth surface and high chromium content of the 17-4 PH SS make it less prone to corrosion. At the same time, it promotes hygiene in food and beverage production since it is easy to clean.

WayKen CNC Metal Services for Stainless Steel Parts

WayKen is the ideal one-stop manufacturer for metal machining services whenever you need stainless steel prototypes and parts for your project. Our engineers, machinists, and quality experts ensure your products meet strict standards. Our CNC machining processes for stainless steel parts involve advanced technologies, including 3-axis, 4-axis, and 5-axis machining, as well as turning, EDM, and surface finishing operations.

At WayKen, we understand the importance of stainless steel in engineering applications due to its exceptional corrosion resistance, strength, and aesthetic appeal. Our machining capabilities cover a wide range of stainless steel grades, including 304, 316, 17-4 PH, and other metals, ensuring that we can meet the specific requirements of your project. Get a free quote today to start your projects!

Conclusions

The stainless steel 17-4ph is a versatile alloy commonly used in several applications because it is cost-effective and offers superior properties such as excellent strength and corrosion resistance. Therefore, knowing everything about the 17-4 PH stainless steel is crucial to achieving the best results when machining your products.

FAQs

What is the 17-4 stainless steel tensile strength?

The 17-4 PH SS has tensile strength that varies on condition. It has a minimum tensile strength of 160,000 PSI and can reach about 210,000 PSI in age-hardened condition.

Can 17-4 PH SS rust?

Stainless 17-4 PH type resists corrosive attacks better than most martensitic stainless steels. However, this alloy can develop light rusting if exposed to a seacoast atmosphere or other corrosive elements for extended periods without proper maintenance.

Is 17-4 PH stainless steel suitable for making welded parts?

Welding is a compatible process for fabricating parts with 17-4 PH stainless steel. You can use arc welding techniques like gas tungsten arc welding (GTAW). However, welding thin steel plates in a solution-annealed condition is best.