Question: Why don’t the Certs for C12L14 and C1215 cold drawn steel bars have mechanical properties routinely reported?
Answer: Because these steels ARE NOT recommended for applications requiring mechanical properties, alternating stress applications, cold metal movement and can also be notch sensitive.
Here are some details from the application notes provided to me when I started as Plant Metallurgist at Bliss & Laughlin Steel in 1985:
- The 1200 series steels (1215 and 12L14) are not generally sold for applications requiring high standards of strength, hardness, or other related properties
- These steels are particularly adapted to automatic screw machine production of small repetitive parts. The ideal application is one where bulk and shape, as dictated by the design, are the chief requirements.
- They may be used for parts which require only nominal strength values providing the factor of safety as in accordance with established practice. This is especially true where the stresses involved are static tension, compression, or shear. Vibratory, torsional, or alternating stress applications approaching the static limits are not recommended; thus these steels should not be used for line shafting.
- When cold drawn, the C-1200 steels are notch sensitive and while polished fatigue specimens will show expected endurance limit values, poor finish and processing of parts, or faulty design may cause low or erratic results for finished parts under dynamic or alternating stresses of relatively small intensity.
- These steels are not recommended for applications involving cold metal movement, such as crimping, forming or bending. Operations such as knurling and character rolling can be done satisfactorily.
- Because of the smaller amount of hot work in rolling, the large size cold drawn C-1200 bars increase in relative brittleness. The large sizes may also be expected to reveal stringer sulfide inclusions on polished surfaces. Further removal will likely reveal more inclusions as they are distributed throughout the bar cross-section.
- A cold drawn surface will not plate to the highest quality finish; a turned or ground surface may prove necessary for critical applications
Your customer wants inexpensive parts, and machining them from 12L14 and 1215 minimizes the cost of machining to the desired geometry. But if the parts are not likely to fulfill the properties expected, that is false economy at best.
Little Charlie and the Night Cats If you Dig It, Don’t Do it.