GCr15轴承钢中TiN夹杂物聚合机理研究

Aggregation mechanism of TiN inclusion in GCr15 bearing steel

在对GCr15轴承钢的扫描电镜观察中发现了尺寸不同的2类TiN夹杂物,包括小尺寸单颗粒TiN和多颗粒聚合TiN。对TiN的热力学计算表明,GCr15轴承钢中TiN夹杂物在固液两相区析出。对TiN生长动力学的计算表明,在初始Ti的质量分数为0.006 0%~0.007 8%和N的质量分数为0.004 9%~0.007 0%,TiN析出的局部冷却速度为0.5~10 K/s,析出温度为1 620~1 640 K的条件下,单颗粒TiN最终析出半径为1~6μm。对多颗粒聚合型TiN形成机制研究表明,其是由单颗粒TiN经历了3个阶段形成的:当有距离较近的单颗粒TiN时,两者之间会自发形成腔桥并通过腔桥力相互吸引靠近;当带有活性的TiN尖端接触后,发生碰撞粗化;各基相发生固相烧结。

Many different types of TiN inclusions were found in the scanning electron microscope observation of GCr15 bearing steel,including single particle TiN,multi-particle polymerized TiN.The thermodynamic calculation of TiN shows that TiN inclusion in GCr15 bearing steel precipitates in the mushy zone.The calculation of TiN growth kinetics shows that:under the condition that the initial concentration of Ti is 0.0060 mass%-0.0078 mass%and the content of N is 0.0049 mass%-0.0070 mass%,the local cooling rate of TiN precipitation is 0.5-10K/s and precipitation temperature is 1620-1640K,the final size of single particle TiN is 1-6μm.The formation mechanisms on multi-particle polymerized TiN reveal that they are formed by single-particle TiN going through three stages as follows:single-particle TiN inclusions approach together by the cavity bridge force;the collision coarsening occurs around the neck region of inclusions ;inclusions and new precipitates are sintered in solid phase state.