冷却工艺参数对海洋工程用H型钢组织性能的影响

通过对SM490YB实验钢进行热轧和超快速冷却实验，研究了不同工艺参数对实验钢厚度方向不同位置的显微组织的影响，分析了SM490YB实验钢的强韧化机理.实验结果表明:随着终冷温度的降低，实验钢厚度方向相同位置的贝氏体和针状铁素体含量逐渐增加，多边形铁素体和珠光体含量减少;实验钢的强度和低温韧性随着终冷温度的降低而增加，终冷温度为480℃、返热温度为554℃时，力学性能最佳.冷却速率的增加可以提高实验钢的强度，但过快的冷却速率会损害材料的韧性.

Effect of Cooling Process Parameters on Microstructure and Mechanical Properties of Marine Engineering H-Beam Steel

The effect of different process parameters on the microstructure and mechanical properties of marine engineering H-beam steel(SM490YB) were studied through the hot rolling and ultra-fast cooling experiments. The mechanisms of strengthening and toughening of SM490YB steel were analyzed. The results showed that with decreasing temperature of the final cooling， the contents of bainite and acicular ferrite increase at the same position in thickness direction of the tested steel， in contrast to those of polygonal ferrite and pearlite. Moreover， the strength and low-temperature toughness of the steel increase with the decrease of the final cooling temperature. When the final cooling temperature is 480℃ and the heat return temperature is 554℃， the performance of mechanical property is the best. The increase of the cooling rate can improve the strength of the tested steel， however the excessive cooling rate can deteriorate the toughness.