中文摘要：

采用热挤压方法制成45钢/25Cr5 MoA/Q235钢三层结构的复合轴,研究了结合界面的组织、Cr元素扩散和结合性能.结果表明：采用热装方式制成的25Cr5 MoA/Q235钢固-固复合坯料,在界面形成一定厚度的氧化皮,即使经过挤压和热处理后,也无法彻底消除结合界面氧化皮对结合性能的影响;采用间隙配合的25Cr5 MoA/45钢固-固复合界面,由于在挤压前经过良好的表面处理,挤压后的界面几乎没有氧化物存在,形成了较为完整的过渡区,经过高温保温过程,在结合界面会形成Cr的碳化物,对Cr和C的扩散起到阻碍作用;经过挤压后,25Cr5 MoA/Q235钢、25Cr5 MoA/45钢结合界面的结合强度均比较低.与复合板相比,复合轴结构上所具有的特点,使其即使初期结合强度较低,也不易产生剥离;经过后续热处理,通过元素的扩散过程,可以提高复合轴的结合强度.

英文摘要：

A 45 steel/25Cr5MoA/Q235 steel clad shaft was made by hot extrusion. Its interface microstructure, chromium distribution and interfacial bonding properties were investigated by scanning electron microscope and microhardness tester. The results showed that an oxide layer with certain thickness was formed in the 25Cr5MoA/Q235 steel interface produced by thermal assembling, which would influence its interracial bonding properties, even after extrusion and hot treatment. For the 25Cr5MoA/45 steel interface produced by clearance fitting, a transition region was formed, where almost no oxide layer was found after extrusion, due to fine surface treatment before extrusion. Chromium carbide was formed in the bonding interfaces after the process of high-temperature holding, which would prevent the diffusion of carbon and chromium. The bonding strengths at the interfaces of 25Cr5MoA/Q235 steel and 25Cr5MoA/45 steel decreased after extrusion. However, compared with a clad plate, the clad layer could still not be peeled from the clad shaft easily even with low bonding strength due to the structural characteristic of the shaft. The bonding strength of the clad shaft could be enhanced after hot treatment and alloying element diffusion.