MANDREL BAR FOR ROLLING OF HIGH ALLOY, METHOD FOR SURFACE TREATMENT OF THE MANDREL BAR, METHOD FOR MANUFACTURE OF THE MANDREL BAR, AND METHOD FOR OPERATION OF SEAMLESS STEEL PIPE PRODUCTION APPARATUS

摘要

A method for surface treating a mandrel bar used for hot rolling of high-alloy seamless steel pipe is provided. The method includes heat treating the mandrel bar to develop a scale, and after heat treatment, rolling ordinary steel comprising 8 % or less of chromium for at least 50 passes. This achieves a mandrel bar for rolling high-alloy steel possessing both durability and superior resistance to seizure