Linepipe steel

摘要

A method of producing coil plate on a hot strip mill is disclosed. The method includes coiling hot rolled coil plate strip at a temperature that is selected (a) to minimize precipitation of Cr/Mo carbides or (b) so that any Cr/Mo carbides that form are sufficiently fine that they go into solution in any subsequent heat treatment of coil plate made from the strip.

主权项

1. A method of producing a linepipe which includes the steps of:
(a) centre-slitting a linepipe steel strip to form a length of slit steel strip, wherein the linepipe steel has the following composition, in wt. %:
C: greater than 0.04 and up to 0.18;Mn: 0.10 to up to 0.38;Ti: at least 0.01;Si: up to 0.35;Nb: up to 0.018;Al: up to 0.05;Ca: up to 0.005;S: at least 0.004 and up to 0.015;P: up to 0.020;Cr: up to 1.0;B: up to 0.002;Ni: up to 0.35;Cu: up to 0.35;V: up to 0.06;Fe: balance; andincidental impurities; and (b) forming the length of slit steel strip into a pipe and electric resistance welding lengthwise extending side edges together to form the linepipe, wherein the linepipe has a weld line toughness of at least 80 J, as measured in Charpy V Impact tests at 0° C., and wherein the microstructure of the linepipe is essentially unchanged by the pipe forming step (b) and is the same as that of the linepipe steel strip before the centre-slitting step (a).