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1 管道和管道连接件多年来的趋势是在不断减少碳当量(由此而减少珠光体含量)的情况下生产出较高强度的管道钢.其目的是生产的管道钢具有较好的韧性和已经改善的焊接性.从20世纪50年代的低强度钢到目前X80所代表钢的化学成分列于表1.炼钢和轧制技术的改进导致世界范围内采用低硫钢,其标准工艺就是用Ca和稀土处理来控制夹杂物形态并同时采用控制轧制.此外,除将硫含量从0.035%大幅度降低到0.001%外,还使钢首先从半镇静钢转变到镇静钢然后到连续铸钢.
1 Pipeline and Pipeline Connections The trend over the years has been to produce higher strength pipe steels with a continuous reduction in carbon equivalent (thereby reducing pearlite content) with the aim of producing ductile steel with better toughness and Improved Weldability The chemical composition of low-strength steels from the 1950s to the current grade X80 steel is summarized in Table 1. Improvements in steelmaking and rolling technology led to the worldwide adoption of low-sulfur steels, the standard process being Ca and rare earth treatments were used to control inclusions and at the same time controlled rolling In addition, in addition to a substantial reduction of sulfur content from 0.035% to 0.001%, the steel was also first transformed from semi-killed steel to killed steel and then to continuous casting steel.