Process Optimization and Properties of Laser Cladding High Speed Steel Coatings on Nodular Cast Iron

Abstract

Rolls in the steel industry withstand very high loads, thermal cycling leading to thermal fatigue, and severe environmental. How to improve the wear resistance and elongate the service life of rolls matters a lot in reducing the consumption of rolls. In recent years, because of its better red-hardness and wear property, high speed steel (HSS) was used to manufacture the new type composite rolls. As a surface treatment technology, laser cladding can fabricate coating to improve the wear resistance of substrate. In this paper, the substrates for laser cladding were nodular cast iron rolls, Nd:YAG solid pulsed laser and continuous wave CO2 laser were both used to explore the feasibility of preparation HSS coatings. The Nd:YAG laser cladding results that the coated layers combined metallurgically with the substrate with a lot of microcracks. The average microhardness up to 600 HV is about 2 times as high as that of the substrate. The CO2 laser cladding results that: fully dense and crack free clad surfaces of high speed steel with an excellent metallurgical bonding were deposited. The average microhardness up to 900 HV is about 3 times as high as that of the substrate. The high-temperature (500 °C) wear rate is 40% of nodular cast iron’s in 30 min.