Investigation of the Laser-Powder Cladding Effect on Steel Surface Hardening

Abstract

The investigation was carried out in the laser-technological complex with the power up to 8 kW, ITAM SB RAS. An inert-gas jet was supplied coaxially with the beam. A protective nozzle from which gaseous Ar was injected was used to protect the hardening joint. The parameters of the laser hardening process with the surface alloying was optimized on the samples of low-carbon steel 20, construction steel 45, and spring steel 65G.Special cladding powders containing carbon, manganese, nickel, chromium, molybdenum, tungsten, silicon, boron, and nitrogen were chosen for laser-powder cladding. They are intended for cladding wear-resistant layers onto machine parts, tools and equipment operated under abrasion-wear conditions with moderate shock loading.It was found that an optimal radiation power was 2 kW. Extra water cooling of treated parts is unpractical during laser hardening because it did not improve the hardening effect. The best effect of surface alloying was reached when the powder of rapid tool steel Р6М5 was injected in the liquid metal pool. High hardness of the clad layer remained at further heating up to 550°C. The use of laser thermal treatment and laser-powder cladding provides thermal hardening and enables increasing hardness and hence wear resistance of low-carbon steel parts by 3 - 4 times, whereas the base part remains viscous.