S17700 17-7 PH 631 Stainless Steel Round Bar

The S17700 17-7 PH AISI 631 stainless steel round bar (Ø260 ASTM S17700 AISI631, SAE 17-7PH) is a chromium-nickel-aluminum precipitation hardening stainless steel that offers exceptional strength and hardness, along with moderate corrosion resistance up to 600°F. This grade can be easily formed in the austenitic condition, similar to Type 301 stainless steel, and can be hardened to high strength levels through relatively low heat treatments that minimize distortion. Its corrosion resistance is comparable to Type 304 stainless steel, especially in the CH 900 temper, making it suitable for a variety of applications, including springs, washers, eyelets, fittings, and fasteners.

Heat Treatment Process

The typical heat treatment process for S17700 17-7 PH stainless steel involves three to four steps:

1. Conditioning using austenite.
2. Cooling, which transforms the austenite into martensite.
3. Precipitation hardening until reaching Condition TH 1050 or RH 950.

To achieve the highest mechanical properties, Condition A material is converted to martensite at the mill through cold reduction to Condition C. After fabrication, a single low-temperature heat treatment is performed to achieve Condition CH 900.

Properties of 631 Stainless Steel Bar

A round bar made from 17-7 PH stainless steel typically boasts good machinability and weldability, facilitating easy fabrication into various components. Its precipitation hardening capability allows for heat treatment to achieve different levels of strength and hardness. The UNS number S17700 refers to 17-7 PH stainless steel, also known as Grade 631 stainless steel. This precipitation-hardening stainless steel provides high strength and good corrosion resistance, making it ideal for applications in aerospace, chemical processing, and other industries.

Applications of 17-7 PH Stainless Steel Round Bars

The S17700 17-7 PH stainless steel round bar (1.4568, UNS S17700) is an austenitic-martensitic precipitation hardening stainless steel developed from 18-8CrNi, also known as controlled phase change stainless steel. The characteristics of the 17-7 PH alloy include its ability to be heat treated for high hardness and strength, excellent fatigue resistance, good corrosion resistance, and minimal heat treatment deformation. This type of stainless steel is commonly used to manufacture:

• Aircraft shells
• Structural parts
• Missile pressure vessels
• Jet engine components
• Springs
• Diaphragms
• Bellows
• Antennas
• Fasteners
• Measuring instruments

The S17700 17-7 PH 631 stainless steel round bar is a versatile choice for demanding industrial applications.