Effect of Process Parameters on Microstructure and Mechanical Properties of Direct Laser Deposited Cold-Resistant Steel 09CrNi2MoCu for Arctic Application

Abstract

Effect of process parameters of microstructure formation and mechanical properties of direct laser deposited parts of cold-resistant steel 09CrNi2MoCu is studied. Due to local properties of buildup depends on thermal cycle during fabrication simulation of temperature field was carried out. The following cases were analysed: deposition of the first layer on massive substrate and deposition of a layer on the buildup far from the substrate. It was established that one time high temperature reheating of deposited layer has no effect on hardness while additional reheating up to lower temperature leads to considerable decrease in hardness by 87-100 HV. Far from substrate hardness and microstructure bands of 0.7-0.8 mm thickness have a hardness variation in the range of 250-300 HV. The area close to the substrate has a microstructure of upper bainite with higher hardness due to higher cooling rates during deposition. In the process of deposited, at a higher power, a quick process of heating and cooling occurs, and vice versa, which forms various products of bainite transformation. From the obtained modes were presented the results of tests for impact strength at low temperatures.