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Heat Treatment

What Buyers Should Know About Specifying Heat Treatment on RFQs

3:05 Min read time
JULY 18, 2025
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When submitting a request for quotation (RFQ) for the heat treatment of metal parts, as a buyer, you are responsible for ensuring that correct and relevant information is included so that an accurate and timely quote can be issued. Heat treatment can be a complex process that may be beyond your level of expertise. If your engineers aren’t providing you with all the necessary information, the result will be vague or incomplete heat treat specifications, which can lead to unexpected costs, delays, and scrap. If you are a buyer issuing an RFQ for parts that require heat treatment, here are some things you should know about the process and what should be included on the RFQ to avoid unnecessary issues.

There is More than One Type of Heat Treatment

Before writing the RFQ, it is a good idea for buyers to have a basic understanding of the different heat treatment processes available and their impact on the parts’ dimensions and tolerances.

Heat treatment is a controlled process involving heating and cooling that changes the metal’s properties without changing its composition. While it may seem straightforward, depending on the desired outcome, there are several different types of heat treatment, including hardening and tempering, carburizing and carbonitriding, annealing, metal stress relieving, brazing, and induction hardening. Each affects a part differently and may need protective atmospheres or masking to avoid unwanted surface changes. Buyers should understand the basics of each type and confirm with engineering which process matches the part’s functional requirements.

Heat Treatment Can Alter the Part

It is also important to understand that heat treatment can change a part’s size and shape. While typically not a drastic change, it is enough to impact dimensions and tolerances. As metals heat and cool, internal stresses may relieve unevenly, causing warping or distortion. Thin walls, tight corners, or large flat surfaces are especially prone to movement. Buyers should work with engineering to confirm the acceptable variation and plan for any final machining or straightening that may be needed. Because heat treatment can alter dimensions, critical tolerances often need to be loosened before heat treatment and then tightened afterward through grinding or machining.

Material Properties Matter

The base material drives how well a part responds to heat treatment. Different alloys need specific time and temperature cycles to reach the target hardness or strength. It is important to be specific. Stating steel alloy, for example, doesn’t provide enough information. Use the correct material designation in the specification, such as SAE 4340 per AMS6409. If a buyer specifies the wrong grade or omits the material condition (such as annealed or pre-hardened), the results may not be as expected. Surface condition also matters, as some treatments can cause oxidation or a soft decarburized layer, which may need to be removed later if surface hardness is critical.

Verify Supplier Capability

Not every heat treater can handle every job. Critical components, especially for aerospace, medical, or defense applications, often require suppliers with the appropriate certifications and process controls. The size of the batch matters too. Parts requiring tight property control typically run in batch furnaces, while high-volume parts are often processed through continuous lines for speed and cost savings. Buyers should ask about the equipment the heat treater uses, verify their qualifications, and confirm whether testing or certification reports will be provided.

What to Include on the RFQ

Including all relevant information on the RFQ as thoroughly as possible will ensure the quote is accurate and will prevent wasted time going back and forth as the vendor tries to fill in missing details. Here are the elements that should be included in the RFQ.

  • Company's legal name and billing and shipping addresses
  • Primary contact’s information, including name, title, email, phone number
  • RFQ type (budget or active order quote)
  • Quotation due date
  • Part description and intended use
  • Part number and current revision
  • Detailed part drawing with current revision level
  • Part shape, size, and weight
  • Critical dimensions and tolerances, note any surfaces that must be masked or protected, and state if any distortion is acceptable
  • Material, including exact alloy and condition (e.g., annealed)
  • Quantity per lot and total quantity if different
  • Heat treatment process required (e.g., carburizing, nitriding, stress relieving) and any special atmosphere needed
  • Target hardness or mechanical properties, with test method if required (e.g., Rockwell C 50 ±2)
  • Specification or standard to follow (e.g., AMS, ASTM)
  • Required testing and certification (e.g., C of C, hardness test report)
  • Lead time requirements
  • Packaging and shipping instructions

Taking the time to get the RFQ right from the start saves headaches later. Clear details help your heat treat vendor provide an accurate quote, plan the right process, and deliver parts that meet your requirements the first time. If you’re unsure about any part of the spec, talk with your supplier early in the process; it’s faster and cheaper to clarify before the work begins.

Bluewater Thermal Offers High-Quality, Cost-Competitive Heat Treatment

Are you ready to streamline your heat treatment process and get parts that meet spec the first time? Operating 10 locations across the US, we provide a range of heat-treating processes designed to improve the mechanical properties, durability, and wear resistance of our customers' metal components. We are CQI-9 compliant and hold ISO 9001:2015, IATF 16949, and AS9100 certifications. For aerospace work, we maintain NADCAP accreditation (AMS 2759/1, 2 & 7) and are an approved supplier for multiple aerospace OEMs. These certifications mean your parts are processed to strict industry standards, with full traceability and documented quality control.

Tell us how we can help

Bluewater Thermal Solutions specializes in all types of heat treating processes including brazing, nitriding, boronizing, carbonitriding & carburizing, and more. We offer a wide array of heat treating and boronizing processes at 11 different locations. To find out how we can serve your induction hardening needs, call us today at 877.990.0050, or request a quote on our website for services.

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