CAJ | 학술논문

利用PCY热膨胀仪（热膨胀系数仪），以2℃/min的加热/冷却速率，测定了含Nb微合金钢Q345B， Q345C和管线钢 X70的临界点温度Ac1, Ac3, Ar1和Ar3，并依据膨胀曲线图计算出它们的热膨胀系数。试验结果表明，对Q345B和Q345C进行加热时，它们的临界点Ac1和Ac3大致相同，分别相差8℃和3℃；而冷却时的临界点Ar1和Ar3，分别相差23℃和25℃。由于在X70钢中，含有更多的微合金元素Nb, V, Ti等，它们的碳氮化物的溶解和析出会对钢材的相变带来较大的影响，所以X70钢的各个临界点温度比Q345B和Q345C高出许多。但所测试的3个钢种的热膨胀系数没有太大的差别。
이용PCY열팽창의（열팽창계수의），이2℃/min적가열/냉각속솔，측정료함Nb미합금강Q345B， Q345C화관선강 X70적림계점온도Ac1, Ac3, Ar1화Ar3，병의거팽창곡선도계산출타문적열팽창계수。시험결과표명，대Q345B화Q345C진행가열시，타문적림계점Ac1화Ac3대치상동，분별상차8℃화3℃；이냉각시적림계점Ar1화Ar3，분별상차23℃화25℃。유우재X70강중，함유경다적미합금원소Nb, V, Ti등，타문적탄담화물적용해화석출회대강재적상변대래교대적영향，소이X70강적각개림계점온도비Q345B화Q345C고출허다。단소측시적3개강충적열팽창계수몰유태대적차별。
The critical points of Ac1, Ac3, Ar3 and Ar1 of Nb-microalloyed steel Q345B, Q345C and pipeline steel X70 were studied by PCY thermal expansion instrument (thermal expansion coefficient apparatus) with 2℃ / min heating/cooling rate, and the thermal expansion coefficients were calculated according to the expansion curves of the experimental steel. The results showed that the difference values of critical points of Ac1 and Ac3 of Q345B and Q345C steel were not large in heating process, which were 8℃ and 3℃, but in cooling process the temperature differences of Ar1 and Ar3 were 20℃ and 25℃ respectively. As there was more microalloyed elements of Nb, V, Ti, etc. containing in X70, the dissolution and precipitation of carbon nitride brought about greater impact on the phase transformation of steel, the critical point of X70 is much higher than that of Q345B and Q345C. There is no much difference in the expansion coefficients of the three tested steel .