Low Carbon Manganese-Nickel-Niobium Steel. An Alternative Route to Produce X65 to X75 Pipeline Grades Applying Relaxed Rolling Conditions

摘要

Experimental heats of a low carbon-manganese-0.5% nickel-0.15% niobium steel have been rolled to plates between 13.5 and 50 mm thickness and to a 16 mm hot strip. Various combinations of soaking temperatures form 1100 exp 0 C to 1300 exp 0 C and of finish rolling temperatures between 710 exp 0 C and 930 exp 0 C have been investigated. From mechanical properties obtained, one can conclude that the investigated steel composition provides very good properties e.g. for pipe steels X65 to X75. In particular, the toughness at low temperature is outstanding despite relaxed rolling conditions. Metallographic and special investigations such as electron microscopy, texture evaluation and chemical extraction, correlated with applied rolling schedules and the mechanical properties obtained resulted in a comprehensive understanding about the benefits of high niobium metallurgy combined with nickel addition. All practically applied welding processes generated mechanical properties, in particular toughness of the weldment, that meet arctic specifications. (Atomindex citation 16:033716)