Microstructure characteristics and properties of 40Cr steel treated by high current pulsed electron beam

In the present work, the surface morphology, phase compositions, surface roughness and microhardness of 40Cr steel subjected to pulsed melting with a high current pulsed electron beam (HCPEB) have been investigated. The results show that after the HCPEB treatment, the number of the scratches on the surface is decreased and even disappeared, and the craters emerge on the irradiate surface, which is accompanied by the formation of the extended graded structures characterised by the non-uniformly hardening in the samples. When increasing the number of HCPEB pulses, the area density of the craters and the surface roughness decrease, but the size of the craters, the thickness of the modified layer with improved microhardness and the average hardness increase. The main reasons are discussed.