合金铸铁聚焦光束表面强化技术

Surface Hardening of Alloy Cast Iron with Light Beam

关键词:  聚焦光束表面强化  合金铸铁  工艺参数  组织  性能

Key words:  surface hardening with light beam  alloy cast iron  parameters of light beam  structure  property

摘要:

采用氙灯辐射聚焦光束做热源对合金铸铁进行表面熔凝处理,研究了熔凝处理层的组织和性能特点及光束工艺参数对组织和性能的影响。研究表明,采用聚焦光束熔凝处理技术可在合金铸铁表面获得一个深度为毫米级、硬度为Hm850的强化层,调节功率密度和扫描速度可有效控制强化层深度和宽度。当输入功率为5 kW,扫描速度为3.5 m/h时,一次熔凝处理宽度可达12 mm。经光束熔凝处理后的合金铸铁组织有分层现象,采用较低的扫描速度时,熔凝处理区的表面存在硬度很低的失碳层,中部是亚共晶莱氏体组织,而处理层底部为莱氏体和共晶石墨共存的麻口组织。提高光束扫描速度可减少熔凝区碳的烧损量,抑制表面失碳层的产生。

Abstract:

Surface melting of alloy cast iron with the light beam of a xenon lamp, microstructures and properties of melted layer and the influence of light beam parameters on them were investigated. The results show that melted layer of white iron with a depth of millimeter level and micro hardness of 850 kgf/mm² can be obtained on the surface of cast iron by using the light beam. The depth and width of melted layer can be controlled effectively through adjusting the density of light power and scan rate. A single pass melting width can be up to 12 mm, when the input power is 5kW and scan rate is 3.5m/h. The light beam melted zone of alloy cast iron obtains a lamellar structure. At the lower scan rate the melted layer consists of a carbon poor zone with very low hardness in its surface, a sub eutectic ledeburite in its middle and a mixture with ledeburite and graphite eutectic at its bottom. The lose of carbon can decrease with increasing of light beam scan rate and therefore the carbon poor zone is inhibited.