What does "cold work hardening" mean in cold-rolled round bar?
It refers to the phenomenon in which metal grains deform during rolling, resulting in increased strength and hardness, but decreased plasticity and toughness.
What is intermediate annealing?
It is a process in which excessive deformation (exceeding 20%-60% of the total deformation) is achieved by heating at 650-850°C to relieve stress and restore plasticity.
Process and Production
What are the key steps in cold-rolled round bar production?
Billet preparation → Rolling/drawing (controlling deformation per pass to ≤15%) → Lubrication and cooling → Intermediate annealing (as needed) → Finished product cooling and handling.
Why is lubrication necessary during rolling?
It reduces friction between the rolls and the billet, removes heat, reduces wear, and ensures surface quality. Emulsions or mineral oils are commonly used.
What are the differences in the cold-rolling characteristics of different stainless steels?
Austenite (304): Significant work hardening, requiring frequent annealing;
Ferrite (430): Low degree of hardening, allowing for increased deformation;
Martensite (410): Poor plasticity, requiring strict control of deformation ≤10%.