1.4848 Nitriding Furnace Tray-type Heat Treatment Fixtures

Nitriding Furnace Heat Treatment Fixtures

Nitriding furnace heat treatment fixtures are the "silent guardians" of the nitriding process. The quality of their design is directly reflected in the uniformity and repeatability of the nitrided case, as well as production costs. An excellent nitriding fixture designer must achieve a perfect balance among fluid dynamics (atmosphere flow), materials science (nitriding resistance), and mechanical design (load-bearing and positioning). Selecting the correct nitriding-resistant material (e.g., AISI 314) and ensuring sufficient atmosphere flow are the two cornerstones of successful nitriding fixture design.

Nitriding furnace heat treatment fixtures are support and securing devices specifically designed for processes such as gas nitriding and ion (plasma) nitriding. The core design principle is to ensure uniform circulation of the furnace atmosphere to achieve a stable and uniform nitrided case, while maximizing the loading capacity and minimizing workpiece distortion.

Unlike quenching fixtures, nitriding fixtures do not need to withstand severe thermal shock. However, they must remain stable throughout the typically long process cycles (often tens to hundreds of hours) and withstand the corrosion from active nitrogen atmospheres and the risk of hydrogen embrittlement.

I. Core Design Goals and Challenges

1. Atmosphere Flowability (Primary Goal): Ensure that active nitrogen-containing gases (e.g., NH₃, N₂, H₂) can uniformly surround each workpiece, avoiding "dead zones" that cause uneven case depth or soft spots.

2. Loading Efficiency: Maximize the load per batch to reduce per-part cost, without compromising gas flow.

3. Preventing Workpiece Distortion: Properly support workpieces, especially slender rods or thin-walled parts, to prevent distortion from self-weight or mutual extrusion under prolonged high temperature (typically 480-580°C).

3. Resistance to "Nitriding" and Hydrogen Embrittlement: The fixture itself will form a brittle nitride layer on its surface after long-term service in the nitriding atmosphere, which can easily spall or crack after repeated use. Additionally, hydrogen atoms may diffuse into the material, causing hydrogen embrittlement.

4. Cleanliness and Maintenance: Oxide scale or contaminants on the fixture surface can release impurities and interfere with the nitriding process, so fixtures must be easy to clean.

II. Main Types and Structures
1. General-Purpose Hanging Racks and Trays;
2. Dedicated Fixtures;
3. Ion (Plasma) Nitriding Specific Fixtures;
4. Large Component Support Systems;

III. Key Points for Material Selection
Material selection for nitriding heat treatment fixtures is critical. The wrong material becomes a consumable and can even contaminate the workpieces.

1. Ideal Material Properties:

• Excellent Nitriding Resistance: Low solubility for nitrogen at nitriding temperatures,Not easy forming a thick, brittle compound layer.
• High-Temperature Strength and Creep Resistance: Maintains dimensional stability under prolonged high temperatures.
• Low Coefficient of Thermal Expansion: Reduces stress caused by differential thermal expansion/contraction with the workpiece.
• Good Resistance to Hydrogen Embrittlement.

2. Commonly Used Materials:

• Austenitic Heat-Resistant Steels: Such as AISI 314 (25Cr-20Ni) and 330 (35Ni-18Cr) are the best choices. Their high chromium and nickel content forms a protective chromium oxide (Cr₂O₃) surface layer that effectively blocks nitrogen atom diffusion inward, resulting in an extremely thin self-nitrided case and long service life.
• Nickel-Based Alloys: Such as Inconel 600, offer superior performance and extremely strong nitriding resistance, but are costly. Used for critical or long-service fixtures.

3. Materials to Avoid:

• Low-Carbon Steel/Plain Alloy Steels: Nitride rapidly and become brittle, cracking and failing after just a few cycles.
• Martensitic Stainless Steels: Also nitride severely.
• Copper and Copper Alloys: Although they do not nitride, they lack high-temperature strength and may contaminate the atmosphere.

Material Grade Table:

FAQ:

Q: How to give inquiry ?

A: Step 1, please give us some details about your furnace,operating temperature,cooling method,loading weight of your furnace and so on;

Step 2, it's better to provide 3D drawings;

Step 3, when we have enough details, we may design the products drawings and quote accordingly;

Q: When can I get the price?

A: We usually quote within 24 hours after we get your inquiry(Except weekend and holidays). If you are very urgent to get the price, please email us or contact us in other ways so that we can offer you a quote.

Q: When will make delivery ? /What is the delivery Time?

A: -Sample Order: 35 days after receipt of the full payment.

-Stock Order: 10 days after receipt of the full payment

-OEM Order: 30 days after receipt of the deposit.

Q: What's your after-sales service?

A: 1 year warranty for all kinds of products;

If you find any defective accessories first time, we will give you the new parts for free to replace in the next order, as an experienced manufacturer, you can rest assured of the quality and after-sales service.

Q: What's your payment condition?

A: T/T

Payment<=USD10000, 100% in advance. Payment>USD10000, 50% T/T in advance ,balance before shipment.

Q: What is the shipping method?

A: Transported by DHL, UPS, EMS, Fedex,Air freight, sea freight or train freight.