The development and removal mechanisms of wire rod mill scale are outlined with the aid of the Fe-0 diagram. Data obtained in field experiments and laboratory experiments show that factors such as thickness and composition of the scale, presence of cracks and rod surface roughness have large effects on the pickling property and mechanical descaling property of scale. Further, laying temperatures, cooling rates, temperatures at the end of cooling and the conditions controlling roll roughness that are necessary for obtaining a good descaling property are described.

Synopsis:Effects of processing variables on the properties of high-strength, high-toughness hot rolled coils for high-test linepipe have been studied. Through laboratory and trial production tests using low C-high Mn-Nb-V and low C-high Mn-Nb-Mo steels, it has been confirmed that by the combination of lowering and rough rolling of more than 85% reduction, an austenite grain size after rough rolling is refined to the ASTM 8. These conditions are essential to obtain final products with fine grained ferrite structure free from bainite and accordingly low ductile to brittle transition temperature, especially when the total reduction during finish rolling is limited to less than 50% due to a heavy thickness of the products.

No abstract

No abstract

No abstract