Corrosion Performance Comparison Of Haynes Series Alloys

Haynes alloy introduction

 

Regarding the customer inquiries we received concerning corrosion performance testing of Haynes series alloys, we have compiled information on the corrosion properties of Haynes series alloys and related solutions. Let's take a look.

 

When selecting Haynes series alloys, the decision often needs to be made based on the specific corrosive environment. Understanding the characteristics of different corrosive environments can help you make a more accurate choice.

 

(Note: This article is based on the core issues raised by some customers who have purchased Haynes alloys, and explains the relevant theories and experiences. Your corrections are welcome.)

 

Key Considerations for Material Selection in Different Corrosive Environments

There are roughly four types:

 

1. High-Temperature Oxidation Environments: This refers to the process of a material reacting with oxygen in high-temperature air (or an oxygen-rich environment).

Preferred Choice: For extreme conditions above 1100°C, Haynes 150 is the preferred choice, offering superior oxidation resistance compared to Haynes 230.

Economic Balance: Below 1100°C, Haynes 230 is a proven and reliable option, achieving a good balance between performance and cost.

 

2. Hot Corrosion Environments (Sulfation/Sulfate): When fuel contains sulfur or the environment is saline, highly destructive sulfate melt deposits can form at high temperatures.

Top Choice: Haynes 188, with its high chromium content and crucial lanthanum, forms a stable and strongly adhering chromium oxide film, specifically designed to combat sulfate hot corrosion, making it the ideal choice for this environment.

Alternative options: Haynes 25/L-605 and Haynes 747 also possess good resistance to sulfidation and hot corrosion and can be considered as alternatives.

 

3. Molten salt environments: Specifically refers to extreme conditions involving contact with media such as fluoride salts in advanced nuclear reactors (such as molten salt reactors).

According to a study on molten salt corrosion, amorphous iron-based and nickel-based coatings exhibit superior corrosion resistance compared to the Haynes 230 substrate. This suggests that in such extreme environments, the base alloy may require a protective surface coating to meet long-life requirements.

 

4. Acidic aqueous solutions:

Among common Haynes alloys, Haynes 747 is known for its good corrosion resistance in a variety of industrial chemical media. If your equipment faces both high temperatures and chemical corrosion (such as in chemical and petrochemical plants), it can be considered as an option.

 

Haynes series alloy material comparison

Haynes 188

Haynes 25

Haynes 230

 

 

 

Procurement and Processing Practical Guide

As a procurement professional, besides material properties, these practical points are equally crucial.

 **Define Standards and Certifications:**

 

When procuring materials, it is essential to clearly define the technical standards (e.g., AMS, ASTM) to be followed and require suppliers to provide complete Material Test Records (MTRs) to ensure that composition and performance meet standards. For critical aerospace components, supplier certifications such as AS9120, CE, and ISO are a threshold (see Lork Alloy - About Us, or contact us directly for details).

 

**Focus on Smelting and Heat Treatment Processes:**

The inherent properties of a material are determined by the smelting process. Haynes Alloy generally requires confirmation of the use of Vacuum Induction Melting (VIM) or a more advanced VIM + Electroslag Remelting (VAR) process to ensure purity and uniform microstructure. Simultaneously, the heat treatment state of the delivered product (e.g., solution state) must be clearly defined, as this directly affects subsequent processing and final performance.

 

**Consider Weldability and Machining Performance:**

Considering machinability, most Haynes alloys are weldable, but Haynes 188 and Haynes 25/L-605 are considered to have relatively better weldability. All high-temperature alloys exhibit a strong tendency for work hardening, requiring a strategy of low cutting speeds, high feed rates, and the use of wear-resistant carbide cutting tools.

 

Core Material Selection Decisions

 

In summary, you can follow this decision-making framework:

--To combat sulfate thermal corrosion → Focus on Haynes 188 without hesitation.

 

--To handle extreme high-temperature oxidation (>1100°C) → Prioritize Haynes 150.

 

--To strike a balance between high-temperature oxidation and cost → Haynes 230 is a reliable choice.

 

--For components that simultaneously withstand high temperatures, stress, and chemical corrosion → Consider Haynes 747.

 

--For applications involving medical implants or combating sulfidation → Haynes 25/L-605 offers unique advantages.