Microstructure, Recrystallization, and Mechanical Property Evolutions in the Heat-Affected and Fusion Zones of the Dissimilar Stainless Steels

Abstract

The purpose of this study was to discuss the microstructure, recrystallization, and mechanical property evolutions in the heat-affected zones and fusion zones during dissimilar stainless steels welding. The morphology, quantity and chemical composition of the -ferrite were analyzed by using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and electron probe micro-analyzer (EPMA), respectively. The recrystallization phenomenon was evident with the second pass heat-affected zone (HAZ-2) and indicated equiaxed grains after second pass welding. The contents of -ferrite exhibited the highest value of all situations in the first pass fusion zone (FZ-1) during the first pass welding. Furthermore, the solidification mode of fusion zones transformed from massive as well as acicularferrite into lathy and skeletal structures as increased the welding pass number from 1 to 3.

Dendrite evolution of delta (δ) ferrite and precipitation behavior of sigma (σ) phase during multipass dissimilar stainless steels welding

“…Experimental results indicate the order of grain size of the δ-ferrite in the multipass FZs as: D 304/430 >D 304-1 >D 304-2 . Hsieh et al [29,30] have attributed the grain size of δ-ferrite decreasing in the multipass pass fusion zones when the welding pass increased to the δ/γ phase transformation. In this study, we believe that the finer d-ferrite in the multipass FZs comes from the δ/γ phase transformation.…”

Microstructural characterization and mechanical performance along the thickness of electron beam welded stabilized AISI 321 stainless steel

“…SEM and EDS were taken on the white area (spectrum 2) and is shown in Figure 3d, which depicts the increase in the Cr and Si content, which are ferrite stabilizing elements. Chih Chun et al [33] also reported that the Cr and Si content increase plays a vital role in ferrite stabilization. Simultaneously, the EDS at a dark area (spectrum 3) shown in Figure 3c has the higher nickel percentage confirming it as the austenite matrix.…”

Effect of Heat Input on Microstructural and Mechanical Properties of AISI 304 Welded Joint Via MIG Welding

“…Increasing in hardness is only due to the larger contents of δ-ferrite in the weld zone and finer grain size in the HAZ by increasing heat input [18]. From the previous research it is very clear that the presence of δ-ferrite in the weldment enhance the mechanical properties [19]. Hardness in HAZ is still higher than the parent metal (PM), this is only due to rapid cooling of weldment leads to refinement of the grains.…”