Cold-Finished Steel Bar: Options and Benefits
Cold-finished steel bar can provide fit-for-purpose material characteristics across a wide variety of applications.
The term “cold-finishing,” however, is used to describe a number of different processing options, and it can be difficult to know which choice is right for a given challenge.
I created this article to provide some clarity, explain the fundamentals of cold finishing, and outline the differences (and benefits) of different types of cold-finished steel bar.
What is cold finishing?
Cold finishing is a broad term used as a descriptor for a variety of value-added steel processes affecting surface quality and physical properties.
Cold finishing can be used to achieve:
Close-dimensional size tolerances
Consistent and controlled straightness
Improved surface quality and enhanced surface finish
If drawn, increased tensile and yield strengths
Special geometric cross-section possibilities, such as hexagons and squares.
A major benefit of cold finishing is that the bars can be directly introduced as semi-finished feedstock for manufacturing, reducing processing time and the need for intermediate manufacturing steps.
You can find an overview of Jade Sterling’s cold-finished steel offerings here.
What are some important cold finishing options?
The table below provides an overview of prototypical cold finishing options, applications, and associated specifications. This guide is intended for educational purposes and is not intended as a comprehensive resource.
| QUALITY DESCRIPTOR | TYPICAL APPLICATIONS | CHARACTERISTICS | ASSOCIATED SPECIFICATIONS |
|---|---|---|---|
| Cold Finished • Turned • Turned and Polished • Turn, Ground and Polished |
• Aircraft Quality • Bearing Quality • Cold Work Quality • Restrictive Quality • Straightness |
• Restricted Size Tolerance • Straightness • Decarburization • Surface Finish / Cosmetics |
• ASTM A29/A29M • ASTM A108 • ASTM A322 • ASTM A576 |
| Cold Drawn • Cold Drawn • Cold Drawn/Stress Relieve |
• Aircraft Quality • Bearing Quality • Cold Work Quality • Improved Mechanical Properties • Straightness |
• Increased Mechanical Properties • Dimensional Control / Size • Tolerance • Surface Quality |
• ASTM A29/A29M • ASTM A311/A311M • ASTM A576 |
These processes may be employed individually or in combination to achieve the needed characteristics. For example, Jade Sterling Steel customers may choose from any of the following categories:
COLD FINISH PROCESS COMBINATIONS
Turned
Turned and Polished
Turned, Ground and Polished
COLD DRAW PROCESS COMBINATIONS
Cold Drawn
Cold Drawn and Turned
Cold Drawn, Turned and Polished
Cold Drawn, Turned, Ground and Polished
I explain further details on each of these options below.
Cold-Finish Processes
Cold finish processing can be specified based on specific steel processing and end-use quality requirements. Common requirements might be, for example: a surface finish, decarb-free, improved dimensional tolerance, and enhanced mechanical properties.
Cold Finished: Turned
Turning refers to surface removal (machining) to achieve a specific size tolerance and a clean surface finish. Turning also removes any decarburization from prior rolling and thermal treatments that could locally soften the surface.
Typical cold finish size tolerances are always +0 / - dim., min. (value).
Turned and Polished
Turning and polishing provides all the benefits of turning, with the addition of a polish operation for a smoother, brighter finish.
You can find further details about Jade Sterling’s turned and polished steel options here.
Turned, Ground, and Polished
Turned, ground, and polished bars have an additional centerless grinding operation that produces superior surface smoothness and dimensional accuracy. We recommend reaching out to a Jade specialist to discuss your requirements for dimensional control.
Cold Drawn Processes
Cold drawing is the process by which hot-rolled steel is pulled through a die of a smaller cross-sectional area. This may be done bar-to-bar, coil-to-bar, or coil-to-coil. It is preceded by a descaling process. Coatings may be applied to carry lubricant.
A key to cold drawing is the diameter of “reduction,” typically ranging between 0.03” – 0.188”, though sometimes heavier drafts can be employed. The process provides both tight dimensional tolerance and increases the steel’s tensile strength, yield strength, and hardness.
If appropriate, a subsequent low-temperature stress relief thermal treatment may be used to reduce residual stresses. In combination with annealing, cold working can also be used to help optimize annealed spheroidal microstructure.
Cold-drawn steel can be a great option for applications requiring superior precision compared to hot-rolled bars straight from the mill. You can learn more about Jade Sterling’s cold-drawn steel offerings here.
Learn More About Steel Metallurgy
Cold finishing and cold drawing can provide significant added value to steel bar stock for various manufacturing applications. Cold finishing is just one of many types of value-added processes for steel bar, and I look forward to exploring these and other steel-related topics in future editions of the Ask the Metallurgist blog.
Jade Sterling Steel supports customers with metallurgical expertise, decades of steel market experience, and extensive supplier relationships. If you have any questions about the right finishing process for your application, please don’t hesitate to reach out.
Your Jade Sterling customer sales representative will be pleased to assist with discussing your needs and possible solutions—always with assistance from a professional inside metallurgical and quality resources.
Please reach out to our team if you have any questions or topics you would like to see covered in the future.
About the Author
Andrew Freborg
Andrew Freborg is the Metallurgy Director with Jade-Sterling. He is a licensed Professional Engineer in the State of Ohio, with 35 years of experience in process and product ferrous metallurgy. He has a BS in Metallurgical Engineering from the Illinois Institute of Technology and an MS in Mechanical Engineering from the University of Akron. His professional experience includes 6 years in automotive/aerospace steelmaking with Republic Engineered Steel (1989-1995), 21 years in steel processing research and development with DANTE Solutions (1996-2017), and 6 years in steel product metallurgy quality management. As a Senior Process Engineer within Republic’s primary steelmaking division, his career focused on the development of steel refining and casting practices to control cleanliness, as-cast bloom quality, and developed steel properties in subsequent processing. At DANTE Solutions, Mr. Freborg worked collaboratively in applying computational process modeling methods to address various processing challenges within the ferrous metals industry, including continuous cast mold design, thermal stress characterization, and ferrous alloy heat treatment. His principal focus was researching of quench hardening processes to improve the bending fatigue strength of helicopter transmission gears US Army AATD, and in support engineering with the Lockheed-Martin / Sikorsky’s FARDS program. Currently, Mr. Freborg oversees product metallurgy for Jade-Sterling.
