The hot rolling steel sheet and its production method for the line pipe very low temperature shocking tenacity being superior

摘要

As for this invention, C: 0.04 - 0.07 weight %, Mn: 1.50 - 1.65 weight %, Si: 0.15 - 0.25 weight %, P: 0.010 weight % below, S: 0.003 weight % below, Nb: 0.040 - 0.060 weight %, V: 0.040 - 0.060 weight %, Ti: 0.010 - 0.020 weight %, Mo: 0.10 - 0.30 weight %, Ni: 0.10 - 0.30 weight %, the molten steel of remaining Fe and the steel and the aforementioned constitution which consist of the other inevitable impurities at the time of outdoor refinement, with Ca-Si it spheroidizes process the debris the throb which stage and it was spheroidized was processed last pass after the stage and the re-heating which with the 1150C - the 1180C re-are heated (Pass) the time, ratio 25 under pressure - 30%, for guaranteeing the stage and the needle-shaped organization which are rolled roughly at finishing temperature 900 - the 930C, after the stage and the sudden cooling which it finishes rolls at finishing temperature and 790 - the 830C with 540 - the 580C retraction the stage which is done and, the line where the very low temperature shocking tenacity which consists of is superiorProduction method of the high tension steel for the pipe is offered.Like this invention, strength of course the high tension hot rolling steel for the line pipe which possesses the shocking tenacity which is superior even under very low temperature environment being offered, is a life extended effect of use such as crude oil transport pipe even at arctic area by controlling the component system of the steel appropriately. Selective figure Figure 2