Ti对高硼钢显微组织和高温力学性能的影响

采用SEM和XRD研究了Ti对高硼钢显微组织的影响。采用冲击试验机、热力学模拟实验机、氧化增重法分析了Ti对高硼钢室温冲击及850℃高温力学、抗氧化性能的影响。结果表明,添加Ti后,基体内硼化物形态圆整、呈离散状分布,尺寸大幅减小。这种硼化物形态、分布的优化提高了高硼钢的室温冲击韧性。高硼钢中添加Ti后在基体内形成了TiC析出相,并使基体由单一奥氏体转变为奥氏体+铁素体双相组织。添加Ti元素后,B含量较低时提高B含量可以提高材料的高温力学性能;但B含量较高时,高温力学强度变化不大。B含量为0.33%(质量分数)时,材料的高温力学性能最佳。添加Ti前后高硼钢的850℃氧化测试结果均符合GB/T 13303-1991中2级"抗氧化性"标准,Ti的加入有利于提高高硼钢高温抗氧化性能。

Effects of Ti on microstructure and high temperature mechanical properties of high-boron steel

The effects of Ti content to the microstructure of high-boron steel were studied by using SEM and XRD. The effects of Ti on impact properties at room temperature, high-temperature mechanical properties and oxidation resistance at 850 °C of the steel were researched by using impact tester, dynamic thermal-mechanical simulation testing machine and oxidation weight increase method. The experimental results showed that the boride granules which distributed in a discrete manner within the matrix exhibited a round and smooth morphology and the boride size decreased greatly after adding Ti. The optimization of boride morphology and distribution made the absorbed impact energy of the steels increased. TiC particles would precipitate and ferrite would form after adding Ti. At a low level of boron content, the high temperature mechanical properties increased with increasing of born content, while at a higher level of boron content, the high temperature mechanical properties had little change. Optimum high temperature mechanical properties were obtained when boron content was at 0.33wt.%. The 850 °C oxidation test results of the steels pro and after adding Ti were all in accordance with grade 2 oxidation resistance standard in GB/T 13303-1991. Ti was conducive to the improvement of the high temperature oxidation resistance properties.