Invar 36 Round Bar Buying Guide – Size, ASTM F1684, MTC & Specifications

Primary Focus Keyword: Invar 36 Round Bar

Secondary Focus Keywords:
Invar 36 Round Bar Supplier, Invar 36 Bar, Alloy 36 Round Bar, Invar 36 1.3912, Invar 36 UNS K93603, Invar 36 ASTM F1684, Invar 36 ASTM B753, Invar 36 MTC, Invar 36 specifications, Invar 36 dimensions, Invar 36 tolerance, Ni36 round bar

SEO Title: Invar 36 Round Bar Buying Guide – Size, ASTM F1684, MTC & Specifications

Meta Description: Learn how to buy Invar 36 round bar with guidance on sizes, ASTM F1684, 1.3912, UNS designations, MTC, tolerances, inspection and specifications.

URL Slug:
invar-36-round-bar-buying-guide-astm-f1684-mtc

Table of Contents

  1. What Is Invar 36 Round Bar?
  2. Common Names and Designations
  3. Invar 36 Round Bar Standards
  4. How to Specify Invar 36 Round Bar
  5. Invar 36 Round Bar Sizes and Dimensions
  6. Understanding Tolerances
  7. Invar 36 Round Bar Material Condition
  8. Why an MTC Is Important
  9. What Should an Invar 36 MTC Contain?
  10. Inspection and Quality Checks
  11. How to Request an Invar 36 Round Bar Quotation
  12. Questions to Ask Your Supplier
  13. Why Source Invar 36 Round Bar from Manan Steel & Metals?
  14. Frequently Asked Questions
  15. Conclusion

What Is Invar 36 Round Bar?

Invar 36 Round Bar is a cylindrical bar manufactured from Invar 36, a nickel-iron controlled-expansion alloy containing approximately 36% nickel.

The material is also known as:

  • Invar 36
  • Alloy 36
  • Ni36
  • 1.3912
  • Nilo 36
  • UNS designations associated with specific Invar specifications

Unlike ordinary carbon steel or stainless steel round bars, Invar 36 is generally selected for applications where low thermal expansion and dimensional stability are important.

Published industry information identifies Invar 36 for aerospace tooling, optical and laser systems, cryogenic components, electronic equipment and precision engineering. (carpentertechnology.com)

For buyers, however, simply asking for “Invar 36 round bar” may not provide enough information for an accurate quotation.

The size, standard, condition, tolerance, quantity and certification requirements should also be defined.

Common Names and Designations

International buyers may use different names for Invar 36.

DesignationDescription
Invar 36Common commercial name
Alloy 36Alloy designation
Ni36Nickel-iron designation
1.3912Werkstoff number
Nilo 36Commercial/material designation used in industry
UNS K93603Associated with Invar 36 under certain specifications
UNS K93601Also associated with Invar material in published references
ASTM F1684Invar alloy specification
ASTM B753Specification associated with certain Alloy 36 products

The exact designation should be matched to the required product form and specification.

For example, voestalpine identifies Alloy 36 / 1.3912 / Invar 36 and lists ASTM F1684 for bar, while Carpenter lists additional specification information for its Invar products. (voestalpine.com)

Important procurement point

Do not rely only on a search for “UNS K93603.”

Published sources use several UNS designations within the Invar family depending on material variant and specification. Always confirm the exact standard required by the end application.

Invar 36 Round Bar Standards

A material standard establishes requirements such as chemical composition, mechanical properties, dimensions, testing and other characteristics.

ASTM F1684 is one of the important specifications associated with Invar materials.

ASTM F1684 covers iron-nickel alloys with controlled thermal expansion characteristics and is used for specified product forms and applications.

Other standards may apply depending on the product and customer requirement.

For this reason, a purchase enquiry should not simply state:

“Invar 36 bar required.”

A stronger enquiry would state:

Invar 36 / Alloy 36 round bar, required standard, diameter, length, quantity and MTC requirement.

This reduces the possibility of a specification mismatch.

How to Specify Invar 36 Round Bar

A professional purchase specification should contain several key details.

Material

State the material clearly:

Invar 36 / Alloy 36 / Ni36 / 1.3912

Product Form

Specify:

Round Bar

Diameter

For example:

  • 10 mm
  • 20 mm
  • 30 mm
  • 50 mm

The actual required diameter should be specified by the buyer.

Length

Mention whether you require:

  • Random lengths
  • Fixed lengths
  • Cut lengths

Quantity

State the required:

  • Pieces
  • Kilograms
  • Metric tonnes

Standard

Mention the required ASTM, EN or customer specification.

Condition

If required, specify the material condition, such as annealed or another agreed condition.

Certification

Mention whether an:

MTC / Mill Test Certificate

is required.

Inspection

For critical applications, the buyer may also specify third-party inspection or additional testing requirements.

Invar 36 Round Bar Sizes and Dimensions

The available size range can vary between suppliers, mills, stockists and manufacturing routes.

Invar 36 can be supplied in different dimensions depending on the product form and manufacturing process.

When requesting a quotation, specify the exact:

RequirementExample
Diameter25 mm
Length3 metres
Quantity100 kg
MaterialInvar 36
StandardASTM F1684
ConditionAs required
MTCRequired

The examples above are only a quotation-format example, not a statement of available stock.

For larger or specialized diameters, availability should be confirmed against the supplier’s current stock or sourcing capability.

Understanding Tolerances

Tolerance is particularly important for precision engineering applications.

The nominal diameter alone does not completely define the dimensional requirement.

For example, a buyer may need:

Round bar diameter: 25 mm ± specified tolerance

rather than simply “25 mm round bar.”

The required tolerance depends on:

  • Product standard
  • Manufacturing method
  • Diameter
  • Machining requirements
  • Final application
  • Customer drawing

If the bar will be machined into a precision component, the buyer should communicate the required machining allowance and final dimensional requirement.

Invar 36 Round Bar Material Condition

The condition of the material can affect its mechanical properties and dimensional behavior.

Common requirements may include:

  • Annealed
  • Cold worked
  • Stress relieved
  • Machined condition

The exact condition should be agreed between the buyer and supplier.

This is particularly important when Invar 36 is being used for:

  • Precision components
  • Optical equipment
  • Aerospace tooling
  • Measuring instruments
  • Cryogenic equipment

A supplier should not assume the required condition if the customer’s specification does not state it.

Why an MTC Is Important

An MTC (Mill Test Certificate) provides documented material information associated with the supplied batch or heat.

For industrial procurement, an MTC can help the buyer verify that the supplied material meets the agreed specification.

Depending on the applicable standard and supply arrangement, the certificate may provide information such as:

  • Heat number
  • Material designation
  • Chemical composition
  • Mechanical test results
  • Heat-treatment condition
  • Product dimensions
  • Applicable standard
  • Inspection results

For precision or critical applications, this documentation can become an important part of the procurement process.

What Should an Invar 36 MTC Contain?

The exact certificate format depends on the manufacturer, specification and customer requirement.

However, buyers commonly look for:

Chemical Analysis

The certificate may show the measured content of elements such as:

  • Nickel
  • Carbon
  • Manganese
  • Silicon
  • Chromium
  • Cobalt
  • Phosphorus
  • Sulfur
  • Iron balance

Published Invar 36 data shows approximately 36% nickel with controlled minor elements, but the certificate should be checked against the actual applicable specification rather than a generic online table. (hempel-metals.com)

Mechanical Tests

Depending on the specification, this may include:

  • Tensile strength
  • Yield strength
  • Elongation
  • Hardness

Traceability

Heat or batch identification helps connect the supplied material to the test documentation.

Standard

The certificate should identify the applicable material standard where required.

Inspection and Quality Checks

Before purchasing Invar 36 round bar for a critical application, buyers should determine which inspection requirements are necessary.

Visual Inspection

Check:

  • Surface condition
  • Cracks
  • Visible defects
  • Oxidation
  • General finish

Dimensional Inspection

Check:

  • Diameter
  • Length
  • Straightness
  • Tolerance

Material Verification

Confirm the material designation and relevant certification.

Chemical Verification

For critical applications, additional positive material identification or chemical analysis may be considered.

Documentation Review

Check that:

  • Heat number matches
  • Material specification matches
  • Dimensions match
  • Test results meet requirements
  • Certification is complete

The inspection level should be appropriate for the actual application rather than unnecessarily increasing procurement complexity.

How to Request an Invar 36 Round Bar Quotation

A clear enquiry helps suppliers respond faster and reduces back-and-forth communication.

A useful enquiry can follow this format:

Material: Invar 36 / Alloy 36
Product: Round Bar
Standard: Required ASTM / EN / customer specification
Diameter: Required size
Length: Required length
Quantity: Required quantity
Condition: Required condition
MTC: Required / Not required
Inspection: If applicable
Delivery Location: Destination

Example

Subject: Requirement for Invar 36 Round Bar

Material: Invar 36
Product: Round Bar
Standard: ASTM F1684
Size: 25 mm diameter
Length: 3 metres
Quantity: 100 kg
MTC: Required
Delivery: Mumbai

This format gives the supplier the core information needed to evaluate the requirement.

Questions to Ask Your Supplier

Before placing an order, buyers can ask:

  1. What material specification will be supplied?
  2. What product form is available?
  3. What sizes are available?
  4. What dimensional tolerance applies?
  5. What material condition is supplied?
  6. Is an MTC available?
  7. Does the MTC include chemical and mechanical results?
  8. What is the heat/batch traceability?
  9. What inspection documentation is available?
  10. What is the expected delivery time?
  11. What packing method will be used?
  12. Can the material be supplied according to the customer’s drawing or specification?

These questions are particularly useful for specialized materials such as Invar 36, where the exact specification can be as important as the material name.

Why Source Invar 36 Round Bar from Manan Steel & Metals?

Manan Steel & Metals supplies special metals and industrial metal products for engineering and procurement requirements.

Our range includes Invar 36 Round Bars for customers looking for controlled-expansion alloy material.

Whether the requirement is related to:

  • Aerospace tooling
  • Precision engineering
  • Optical equipment
  • Cryogenic systems
  • Industrial components
  • Specialized fabrication

you can share your exact requirement with our team.

Send the Following Details

For a faster quotation, send:

Material + Diameter + Length + Quantity + Standard + MTC Requirement

Explore Manan Steel & Metals

Invar / Round Bar Products:
https://manansteel.com/round-bar-manufacturer-supplier/

Manan Steel & Metals:
https://www.manansteel.com/

For an enquiry:

Phone: 7977369869
Email: manansteel@gmail.com

Frequently Asked Questions

What is Invar 36 round bar?

Invar 36 round bar is a cylindrical product manufactured from the nickel-iron low-expansion alloy commonly known as Invar 36, Alloy 36 or Ni36. It is primarily selected where low thermal expansion and dimensional stability are important.

What standard is used for Invar 36 round bar?

ASTM F1684 is an important specification associated with Invar materials. Other specifications, including ASTM B753, can also appear depending on the exact product and material requirement. The applicable standard should be confirmed before ordering.

What is 1.3912 Invar 36?

1.3912 is a Werkstoff number associated with Ni36 / Alloy 36 / Invar 36. It is commonly used in European material identification.

What is the UNS number of Invar 36?

Published references associate Invar materials with UNS designations including K93600, K93601 and K93603. The exact designation should be verified against the applicable product specification.

Is an MTC available for Invar 36 round bar?

An MTC can be requested for industrial material supplies. Buyers should specify their certification requirement when requesting a quotation.

What information should I provide for an Invar 36 quotation?

Provide the material designation, diameter, length, quantity, applicable standard, material condition, certification requirement and delivery location.

Is Invar 36 used for precision components?

Yes. Its low thermal expansion makes it useful in applications including precision instruments, optical equipment, laser systems, aerospace tooling and other dimensional-control applications.

Can Invar 36 round bar be machined?

Yes. Invar 36 can be machined using suitable machining practices. The required material condition and machining allowance should be considered when ordering.

Conclusion

Buying Invar 36 Round Bar requires more than specifying the alloy name.

For a technically correct procurement, buyers should define the material designation, standard, diameter, length, tolerance, material condition, quantity and MTC requirement.

The alloy is commonly identified as Invar 36, Alloy 36, Ni36 or 1.3912, while different UNS designations can appear depending on the specific material and specification.

For industrial procurement, always match the material to the customer’s technical requirement and verify the supplied documentation against the agreed specification.

If you require Invar 36 Round Bar for an industrial, aerospace, precision or engineering application, send your required size, quantity and specification to Manan Steel & Metals.

Manan Steel & Metals
Shop No. 2, Hira Building, 97 Khetwadi Main Road,
Girgaon, Mumbai – 400004, Maharashtra, India

Phone: 7977369869
Email: manansteel@gmail.com
Website: https://www.manansteel.com/

Technical References