Microstructure and Mechanical Properties of Inertia‐Friction‐Welded Fe–Cr–Ni–Mo High‐Strength Steel

Abstract

Inertia friction welding (IFW) is a solid‐state welding technology that avoids defects associated with molten weld processes; however, this process has rarely been used to weld ultrahigh‐strength steel (UHSS). Herein, 32CrMnSi2Ni6MoV UHSS is joined successfully via IFW. The mechanical properties after welding at different rotational speeds and the microstructure at 2800 rpm are studied in detail. The temperature distributions in the peripheral and central areas are modeled according to the temperature at the weld zone. The microstructural transformation is analyzed for different temperature intervals, and the microstructural characteristics of each interval correspond to the actual microstructure of the welded joint according to the temperature distribution model. High‐strength martensite forms at the weld zone, and the thermomechanical‐affected zone (TMAZ) in the peripheral region is divided into phase transformation zone, partial recrystallization zone, and plastic deformation zone, whereas the TMAZ in the central region includes only the partial recrystallization and pure plastic deformation zones. This difference is due to the higher frictional heat caused by the higher peripheral linear velocity during rotation. A tensile test shows that fracture occurs in the base metal (BM) region, and the yield strength, tensile strength, and elongation are 805 MPa, 1064 MPa, and 13.88%, respectively.

Effect of Modified Water‐Bath Method on Microstructure and Mechanical Properties of Wire Arc Additive Manufactured Low‐Carbon Low‐Alloy Steel

“…Dimples appear in the fracture surfaces of the air‐cooled and water‐bath sample, exhibiting the characteristics of plastic fractures. [ 33 ] Due to the fine LB grains, the water‐bath specimens have smaller dimples. Figure 12e shows the OM image of the fractured vertical tensile specimens.…”