Effect of different scanning modes on the surface properties of continuous electron beam treated 40CrMn steel.

• Surface modification of 40CrMn steel by multi-pass scanning electron beam process was the first time. • The ring scanning method was conducted during continuous electron beam treatment. • Compared with the single-pass，the surface microhardness under multi-pass electron beam treatment decreased slightly. • The wear resistance after single-pass and multi-pass treatment improved compared to the the untreated samples. Single-pass and multi-pass electron beam surface modification (EBSM) are two of the most important scanning method in the field of electron beam processing. In this paper, microstructure evolution and surface properties of 40CrMn steel treated by multi-pass and single-pass EBSM are compared. It is found that there is obvious difference in microstructure evolution of the treated samples after two scanning modes of electron beam treatment due to these region experienced different thermal circles processes. Moreover, the slight difference in surface microhardness of specimens after single-pass and multi-pass electron beam treatment are supposed to be caused by the formation of tempered martensite and tempered sorbite in the overlap region after multi-pass electron beam treatment. And the wear resistance of the specimens were improved obviously under the two scanning modes of EBSM compared with the untreated specimens. [ABSTRACT FROM AUTHOR]