Stellite Alloy
21

Stellite 21 Introduction

Solid Solution
Strengthened Alloy

Cobalt

Chromium

Corrosion
Resistance

86

Mechanical
Behavior

85

Purity

84

Overview

As a leading supplier & manufacturer in China, AEETHER supply cost-effective Stellite 21 Products.

Stellite 21 consists of a CoCrMo alloy matrix containing dispersed hard carbides which strengthen the alloy and increase its hardness, but also decrease the ductility.

The type, shape, size, and distribution of the carbides is strongly influenced by the processing history of the alloy, and for this reason the mechanical properties of Stellite 21 are very dependent upon the manufacturing route and any subsequent heat treatments.

Due to the low volume fraction of carbides, the Co-based alloy matrix dominates the wear and corrosion properties.

Stellite 21 has excellent cavitation, galling and metal-to-metal sliding wear resistance, but is not recommended for severe hard particle abrasion. The surface can work harden considerably during wear or even during machining, and the use of correct machining tools and techniques is important to achieve optimal results.

Stellite 21 has excellent resistance to thermal and mechanical shock. Stellite 21 is similar to the medical implant alloy AS F-75 and was previously also known as Stellite 8.

Corrosion Resistance

Stellite 21 is resistant to oxidizing and reducing gaseous atmospheres up to 1150°C (2100°F). Because its ternary alloying element is Mo and not W, it has higher resistance to reducing or complex environments (e.g. sulphuric acid, hydrochloric acid, and sour gas) than CoCrW alloys such as Stellite 6. The typical electrode potential in sea water at room temperature is approx. - 0.3 V (SCE). Like stainless steels, Stellite 21 corrodes primarily by a pitting mechanism and not by general mass loss in seawater and chloride solutions.

Physical Properties

Mechanical Properties

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