Mechanical and Corrosion Properties of Nitrogen Bearing Duplex Stainless Steel Sample Prepared by Laser Forming

To meet the needs of repairing and remanufacturing of large-scale equipment, intensive duplex stainless steel powder was designed. It can be used for repairing those large-scale bearing components of Q345, Q460, EQ56 and 18-8 austenitic stainless steel. The laser formed samples were prepared on Q345 and 1Cr1 8Ni9Ti substrates under the protection of 99.999% high-purity nitrogen. The microstructure, mechanical properties, electrochemical properties and the contents of nitrogen in the samples were carefully investigated. Results show that the laser formed layers of nitrogen-bearing duplex stainless steel is prepared under the protection of high-purity nitrogen. The austenite and ferrite distribute uniformly in the samples, and the nitrogen content in the formed layers is approximately 45% lower than that in the powder. The tensile strength, yield strength, elongation and microhardness of the samples is in the range of 940-1040 MPa, 800-910 MPa, 21%-25%, and 275-285 HV0.1, respectively. Under the testing condition with an alternating load of 20 Hz, stress of 330 similar to 600 MPa, the average cycles of the formed samples are about 7 times that of the standard cold-rolled bar of 1Cr18Ni9Ti. The wear volume of the formed samples is 0.3 and 0.5 times of the substrate Q345 and 1Crl8Ni9Ti, respectively. The corrosion potential of the formed samples is 0.364 V higher compared to 1Crl8Ni9Ti. The corrosion current density is 4.34 x10(-7)A/cm(2), lower than that of 1Crl8Ni9Ti. Generally, the formed sample has good comprehensive properties.