AMS specifications, including AMS 5629, are part of an international standard developed by SAE which has become the principal reference in the world for aerospace materials. This grade is what people in the aerospace industry refer to as 15-7 precipitation hardening stainless steel. The numbers in that specification are not random. They indicate the nearest to the actual values of chromium and nickel within that alloy.

With respect of mechanical properties of a material, those elements are the ones that give a material its corrosion resistance.

Pros and Cons of 5629

The benefits of AMS 5629 are the lightweight and corrosion resistance that aerospace grade materials AMS 5629 can withstand with the addition of a good strength material. The solution heat treatment that AMS 5629 specifies sets the material to a state at which it can be formed and machined before going to the aging portion of the process to gain higher strength.

It is important for the industry to understand the characteristics of the product. Parts made using the AMS 5629 alloy can go through an ageing treatment after manufacture, resulting in finer microstructure precipitates, and a subsequently higher strength of the component. The solution treatment and ageing is a process series that is easily integrated into the metal working processes, giving the fabricators a lot of control to meet the needs of the application for the final component.

Uses of the material all AMS 5629

AMS 5629 is the material of choice by aircraft systems designers for a number of structural and mechanical components that require a certain level of strength and corrosion resistance. This alloy is specified for landing gear, all kinds of fittings, fasteners, actuator components and similar parts. The material is particularly suited for application aircraft components, which have moisture and corrosion hazards.

When comparing the 15-7 alloy to other high strength stainless alloys, it can be seen that this alloy has a better machinability in the solution treated condition which is essential in the aerospace industry where complex geometries are standard and tight tolerances are required.

Assurance and Documentation

Aerospace materials are one of the few areas where the requirements are only part of the specification. AMS 5629 materials require a chemical and mechanical property and heat treatment certification, which accompanies the materials through their entire life cycle. Documentation, provided at the start of a job, are critical. 

 AMS 5629 materials must undergo multiple inspections, such as checking mill test documents, dimensional samples, and perhaps, depending on the situation, validation samples.

 Manufacturing and Designs

If parts are made from AMS 5629, one heat treated response needs to be reflected in the design. Parts should have enough room, unless they are high temp, for the heat treat to cause warp. If thin, complex, or highly distorted features are present, distortion control must be addressed.

Since 15-7 stainless can be welded, some engineers try to develop welding procedures for 15-7 stainless. However, an extensive welding procedure development is required for achieving optimal properties of the welded joint. That’s why most engineers avoid welding and use 15-7 for joints where other components can be mechanically fastened.  

Due to the nature of its business, aerospace can be very demanding when it comes to consistency. When an engineer mentions AMS 5629, they refer to a very specific document that clarifies which properties and which material characteristics leaves no room for confusion.