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Contemporary Machining Processes
and residual stress, by changing the nanostructure induced by severe plastic deformations on the surface (Qian et al., 2016). Ultrasonic shot peening (USSP) treatment
is an effective method of fabricating nanocrystalline on the surface of metals. The
USSP process involves a generator of ultrasonic signals, a transducer which translates the generated signals into mechanical motion, and a simple metal rod which
propels the shots. As a result of USSP, a surface nanocrystalline is formed and hardness is obviously promoted (Zhang et al., 2021). Ultrasonic impact treatment (UIT)
can be applied to bulk metallic glasses to obtain tensile yield platforms regardless of
zero tensile plasticity of as-cast ones. Surface gradient heterogeneity caused by UIT
was found responsible for a favorable shearing path and apparent tensile plasticity
(Tu et al., 2021). UST may be combined with other surface treatment methods, e.g.,
electric spark treatment (EST). It was demonstrated by Lei et al. (2010) that surface roughness and residual stress after the ultrasonic treatment were substantially
reduced, and the fatigue life of specimens strengthened by ultrasonic treatments was
about twice that of specimens treated by EST only.
It should be emphasized that UST methods can be widely applied to remanufacturing processes, especially in combination with other methods. A recent study (Ye
et al., 2020) investigated the microstructure and mechanical properties of a Cr–Ni
alloy layer deposited by laser cladding (LC) on the surface of a worn shaft made
of 1045 steel and then processed by hard turning combined with ultrasonic surface
rolling (USR). It was found that USR greatly improved the surface of cladding layer,
so that its roughness decreased by 88.5%. Moreover, the residual tensile stress was
transformed into residual compressive stress. Microhardness, elastic modulus, and
fracture toughness of the cladding layer surface increased significantly after USR.
In order to improve the material removal rate and integrity of a machined surface,
hybrid chemical-assisted ultrasonic machining (CUSM) methods are used. CUSM
is suitable even for highly demanding materials like bulletproof glass (Singh et al.,
2017). Various experiments and comparisons with conventional results of glass
machining proved the superiority of the hybrid method, increasing the MRR up to
200%, improving the surface roughness, and decreasing dramatically the machining
load (Choi et al., 2007). Application of CUSM can provide process efficiency several
dozen times better than EDM and five to six times better than USM, with five times
better tool wear resistance and energy consumption reduced by 60–80% (Koryagin
et al., 2000). Owing to a higher surface quality and compressive residual stresses
in the surface layer, wear resistance and fatigue strength of hard alloy molds, dies,
and other components of engineering systems can be improved with application of
CUSM.
1.8 ELECTRON BEAM MACHINING
The electron beam machining (EBM) process uses electron beams as energy sources
introducing thermal energy in order to remove material from a workpiece by melting
and/or vaporization (Liang and Shih, 2016). The kinetic energy of electrons striking the workpiece surface converts into thermal energy of the material, increasing
its temperature. EBM has been used in aerospace and nuclear industry since 1960,
Contemporary Machining Processes
and residual stress, by changing the nanostructure induced by severe plastic deformations on the surface (Qian et al., 2016). Ultrasonic shot peening (USSP) treatment
is an effective method of fabricating nanocrystalline on the surface of metals. The
USSP process involves a generator of ultrasonic signals, a transducer which translates the generated signals into mechanical motion, and a simple metal rod which
propels the shots. As a result of USSP, a surface nanocrystalline is formed and hardness is obviously promoted (Zhang et al., 2021). Ultrasonic impact treatment (UIT)
can be applied to bulk metallic glasses to obtain tensile yield platforms regardless of
zero tensile plasticity of as-cast ones. Surface gradient heterogeneity caused by UIT
was found responsible for a favorable shearing path and apparent tensile plasticity
(Tu et al., 2021). UST may be combined with other surface treatment methods, e.g.,
electric spark treatment (EST). It was demonstrated by Lei et al. (2010) that surface roughness and residual stress after the ultrasonic treatment were substantially
reduced, and the fatigue life of specimens strengthened by ultrasonic treatments was
about twice that of specimens treated by EST only.
It should be emphasized that UST methods can be widely applied to remanufacturing processes, especially in combination with other methods. A recent study (Ye
et al., 2020) investigated the microstructure and mechanical properties of a Cr–Ni
alloy layer deposited by laser cladding (LC) on the surface of a worn shaft made
of 1045 steel and then processed by hard turning combined with ultrasonic surface
rolling (USR). It was found that USR greatly improved the surface of cladding layer,
so that its roughness decreased by 88.5%. Moreover, the residual tensile stress was
transformed into residual compressive stress. Microhardness, elastic modulus, and
fracture toughness of the cladding layer surface increased significantly after USR.
In order to improve the material removal rate and integrity of a machined surface,
hybrid chemical-assisted ultrasonic machining (CUSM) methods are used. CUSM
is suitable even for highly demanding materials like bulletproof glass (Singh et al.,
2017). Various experiments and comparisons with conventional results of glass
machining proved the superiority of the hybrid method, increasing the MRR up to
200%, improving the surface roughness, and decreasing dramatically the machining
load (Choi et al., 2007). Application of CUSM can provide process efficiency several
dozen times better than EDM and five to six times better than USM, with five times
better tool wear resistance and energy consumption reduced by 60–80% (Koryagin
et al., 2000). Owing to a higher surface quality and compressive residual stresses
in the surface layer, wear resistance and fatigue strength of hard alloy molds, dies,
and other components of engineering systems can be improved with application of
CUSM.
1.8 ELECTRON BEAM MACHINING
The electron beam machining (EBM) process uses electron beams as energy sources
introducing thermal energy in order to remove material from a workpiece by melting
and/or vaporization (Liang and Shih, 2016). The kinetic energy of electrons striking the workpiece surface converts into thermal energy of the material, increasing
its temperature. EBM has been used in aerospace and nuclear industry since 1960,