利用环形激光光内同轴送粉喷头进行单熔道试验和测试, 就中空环形光离焦量对45# 钢表面熔层平整度、平宽度、平高度以及熔覆截面微观组织的影响进行试验研究。通过改变离焦量, 获得单道熔覆层, 并进行单层熔宽、熔高及表面平整度的测试和微观组织的对比, 分析了离焦量对熔层组织、性能和表面状态的影响规律。结果表明: 熔覆层组织在小离焦量情况下细密, 环形光激光熔覆层的硬度、表面平整度随离焦量的变大先增后减, 在较小负离焦状态下可得到最大值。

By using an annular inside-beam coaxial powder-feeding nozzle, single cladding tests are carried out. The effects of hollow-beam defocusing amount on the surface smoothness, width and height of the cladding zone of 45 steel and the microstructure of cladding sections were experimentally investigated. A single cladding zone was obtained and the tests on the width and height of single cladding zone and surface smoothness were carried out by changing the defocusing amount. And this paper analysed effect laws of defocusing amount on the melting layer, properties and surface states. The results showed that the microstructure of melting layer was fine under small defocusing amount.The hardness of annular-laser melting layer and surface smoothness first increased and then decreased with the increase of defocusing amount. And the maximum can be obtained under the smaller negative defocusing amout condition.