Relationships between the castability, rollability and machinability of free-cutting steels from continuously cast strands 150 mm2
Project ID: 7210-MA/113Funded under: ECSC-STEELRES 7C
The continuous casting of low-carbon free-cutting steels in bloom sizes is now state of the art. Although sulphides in the rim zone are smaller, sulphide inclusions are more numerous and oxide purity greater in this zone and, therefore, machinability is equivalent to that of ingot-cast material. In modern finishing mills, continuously cast strands of area 150 mm2 can be finish-rolled to the smallest dimensions in one run. It is thus important to investigate whether this strand cross-section is on a par with continuously cast bloom sizes, taking account of all requirements of quality and of the production technique. In the first rolling trials, the billets showed rupturing at the edges in the roughing train of the finishing mills. This problem was overcome by changing the roll pass design and heating the billets to a higher temperature in the furnace. Large quantities of as-cast billets of area 150 mm2 have since been finish- rolled to under 40 mm diameter and processed by customers. The process of melting, casting and rolling was as effective as with blooms. Billets require no more surface conditioning than blooms, and the surface quality of the finished material is as good as that from blooms. As regards machinability, customers have not made any adverse comparisons. This proves that free-cutting steel products can be manufactured from continuously cast billets with no loss of quality.
Bibliographic Reference: EUR 13480 DE (1991) 80 pp., FS, ECU 7.50
ISBN: ISBN 92-826-2597-4
Record Number: 199111301 / Last updated on: 1994-12-02
Original language: de
Available languages: de