功率对304L车板上激光熔覆Fe-Cr层组织和冲蚀性能的影响

在304L不锈钢车板上激光熔覆Fe-Cr层,通过实验测试的手段研究功率对其组织和冲蚀性能的影响。研究结果表明:对熔覆层进行熔覆过程中引起了组织晶化现象,逐渐提高功率后,晶体组织衍射峰也变得更加明显。经过0.5 kW以上功率的激光熔覆层中已基本观察不到层状组织,获得更致密的组织,实现了熔覆层和基体间的冶金结合作用。随着功率的增加,激光熔覆Fe-Cr层的密度表现出单调增加的变化规律。提高激光功率后,获得了更低硬度的熔覆层。通过喷涂工艺制得的熔覆层与基体间形成了机械结合的状态,使界面组织硬度发生快速降低,熔覆层的硬度呈现阶梯降低的变化规律。相对于304L不锈钢,熔覆层试样达到了更低体积磨损率。以更高冲击角进行处理时,可以使砂粒获得更集中的能量,从而更易在熔覆层中产生凹坑和裂纹,从而提高了体积损失率。

Impact of Laser Power on Erosion Resistance of 304L Stainless Steel Surface Modified with Laser Cladded Fe-Cr Coatings

The surfaces of 304 L stainless steel were modified with the Fe-Cr coatings synthesized by laser cladding.The influence of the laser power on the microstructures and erosion behavior of Fe-Cr coatings was investigated with X-ray diffraction,scanning electron microscopy and sandblasting test.The results show that the laser power had a major impact.For instance,as the laser power increased from 0.5 to 4.0 kW,the wear-resistance/compactness/density of the amorphous Fe-Cr coating with reduced porosity increased,the surface hardness(lower than that of the substrate)decreased with a linearly-decreasing hardness depth profile,accompanied by an increasing interfacial adhesion because the rapid alloying/crystallization/solidification occurred at the interface of cladded Fe-Cr layer and 304 L stainless steel.Small pits and cracks were created on the cladded Fe-Cr coatings by the sandblasting at a large impinging angle.