Abstract
An 800 MPa class high strength low-alloy (HSLA) steel block part was deposited on substrate with similar composition by gas metal arc welding (GMAW)-based wire arc additive manufacturing (WAAM). The base plate could be removed after deposition or retained as part of the additive manufacturing (AM) part, forming the hybrid additive manufacturing (HAM) part. Tensile tests of the AM part and the HAM part were performed at ambient temperature (AT) and elevated temperature (ET, 600°C held for 4 h) for potential applications in high-rise buildings. Microstructure observations and low temperature impact tests were also conducted. Results show that microstructure of the deposit mainly consists of lower bainite and granular bainite. AT yield strength (YS) of the deposit along the deposition, transverse, and vertical directions is ∼770 MPa. ET YS of the deposit along the lateral and building directions could reach 373 MPa, 48.4% of the AT YS. Fracture elongation along all directions could exceed 18.0% for both AT and ET. Low temperature (−50°C) impact absorbed energy of the deposit could exceed 84 J along all directions. Mechanical properties of the HAM part are similar or superior to those of the AM part along the vertical direction, except the AT fracture elongation, which is one-fifth lower. Good strength-ductility-toughness balance of the made part verified the feasibility of using WAAM to manufacture 800 MPa HSLA steel block parts that have potential applications in high-rise buildings, especially considering ET YS of the part might be improved by alloying redesign to meet the performance requirements of building steel.
Highlights
Additive manufacturing (AM), a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies (ASTM F2792-12a), has gained great progress since the later 1980s
Impact tests (−50°C) were performed on samples extracted from hybrid additive manufacturing (HAM) part with the V notch located at different locations, which were denoted by H, M, and L (Figure 2(d)). e microhardness indentation was performed on metallurgical sample with a load of 200 g and the step size was 200 μm
The fracture elongation along Y and Z did not change while the Ultimate tensile strength (UTS) and yield strength (YS) dropped from 840 MPa and 770 MPa to 450 MPa and 370 MPa (Figures 5(c) and 5(d)) when the test temperature was elevated to 600°C
Summary
Additive manufacturing (AM), a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies (ASTM F2792-12a), has gained great progress since the later 1980s. Advances in Materials Science and Engineering by significantly great deposition rate (3–10 kg/h), unlimited building envelope, and low capital cost [7] All these characteristics make WAAM suitable to fabricate fully dense near-net-shaped metallic components for building applications with high forming efficiency at a low investment [8] and maximize the design freedom [9]. High-strength low-alloy (HSLA) steels that contain small amounts of carbon (
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