Microstructure and Mechanical Properties of Low-Carbon High-Strength Steel Fabricated by Wire and Arc Additive Manufacturing

Abstract

Wire and arc additive manufacturing (WAAM) is a novel technique for fabricating large and complex components applied in the manufacturing industry. In this study, a low-carbon high-strength steel component deposited by WAAM for use in ship building was obtained. Its microstructure and mechanical properties as well as fracture mechanisms were investigated. The results showed that the microstructure consisted of an equiaxed zone, columnar zone, and inter-layer zone, while the phases formed in different parts of the deposited component were different due to various thermal cycles and cooling rates. The microhardness of the bottom and top varied from 290 HV to 260 HV, caused by temperature gradients and an inhomogeneous microstructure. Additionally, the tensile properties in transversal and longitudinal orientations show anisotropy characteristics, which was further investigated using a digital image correlation (DIC) method. This experimental fact indicated that the longitudinal tensile property has an inferior performance and tends to cause stress concentrations in the inter-layer areas due to the inclusion of more inter-layer zones. Furthermore, electron backscattered diffraction (EBSD) was applied to analyze the difference in Taylor factor between the inter-layer area and deposited area. The standard deviation of the Taylor factor in the inter-layer area was determined to be 0.907, which was larger than that in the deposited area (0.865), indicating nonuniform deformation and local stress concentration occurred in inter-layer area. Finally, as observed from the fracture morphology on the fractured surface of the sample, anisotropy was also approved by the comparison of the transversal and longitudinal tensile specimens.

Mechanical properties of wire and arc additively manufactured high-strength steel structures

“…In the wire arc additive manufacturing of these geometries, the layer-by-layer build-up approach leads to repeated Recommended for publication by Commission I -Additive Manufacturing, Surfacing, and Thermal Cutting heating of already deposited layers, which affects the mechanical properties of the parts to be manufactured [5][6][7]. Furthermore, the heat introduced cannot be dissipated by surrounding structures, as in the case of joint welds, but is primarily given off to the ambient air.…”

Enhanced Strength-Ductility Synergy of Bimetallic Laminated Steel Structure of 304 Stainless Steel and Low-Carbon Steel Fabricated by Wire and Arc Additive Manufacturing

“…For example, the microstructure of the 304 SS layer in the current BLSS is martensite rather than δ-ferrite embedded in the austenite matrix observed in the bimetallic structure [3]. Compared with the low-carbon high-strength steel fabricated by WAAM [18], where the microstructure consisted of equiaxed, columnar, and inter-layer zones, the current BLSS shows uniform microstructure distribution within each single layer with no significant differences in phase structure.…”

“…Under high cyclic fatigue load, this LMC outperformed homogeneous steel produced by WAAM. Sun et al [18] studied the microstructure and mechanical properties of low-carbon high-strength steel prepared by WAAM, and analyzed the difference in Taylor factor between the interlayer and the deposition region by electron backscatter diffraction (EBSD). It was found that nonuniform deformation and local stress concentration occurred in the interlayer area.…”

Influence of heat input on microstructure and mechanical behaviour of austenitic stainless steel 316L processed in wire and arc additive manufacturing

“…35 They studied tensile properties specimen located at the bottom and intermediate region are anisotropic, but the top region possesses the isotropic properties, the fact is that the specimen in a different direction has various temperatures is closely related to the microstructure, anisotropy property, which are the result of complex thermal effects of additive manufacturing. 36 When 316L stainless steel conventional cast specimens were compared to SLM, hot isostatic pressing (HIP) specimens, the YS (41%) and tensile strength (144%) were found to be significantly greater. The SLM specimens, on the other hand, had lower values than the specimens acquired using the other methods.…”