Research on A131 EH36/AISI 1045 Bimetallic Material Fabricated by Laser Directed Energy Deposition

In the present study, the A131 EH36/AISI 1045 bimetallic structure is successfully fabricated by the hybrid DED and conventional processes. At the interface of the bimetallic structure, a transition zone of about 0.5 mm wide with good metallurgical quality is obtained without large cracks and unfused defects. The interface consists of microstructural refinement zones, coarsening zones, dual heat-affected zones, and heat-affected zones. The hardness in the interfacial region increases gradually along the building direction. The tensile strength, yield strength, and elongation of the as-built bimetallic structure are (629.0 +/- 1.1) MPa, (471.4 +/- 9.2)MPa, and 17.9%, respectively, which increase slightly to (671.3 +/- 5.6) MPa, (572.8 +/- 8.4)MPa and 22.1% after heat treatment. The as-built bimetallic structure is easier to cut than the heat-treated counterpart. When cutting from the AISI 1045 to the A131 EH36 regions, the cutting force decreases significantly with the maximum reduction of 64.1%. In addition, the surface roughness of the ultra-precision machining face decreases from(111.8 +/- 13.6) nm in the AISI 1045 region to (107.0 +/- 10.4) nm in the A131 EH36 region.