Production Of Duplex Stainless Steel Composites Via Accumulative Roll Bonding

In this work, ceramic particles were introduced to produce duplex stainless steel (DSS) matrix composites via accumulative roll bonding (ARB) at1100℃. The effect of the rolling direction, the types of ceramic particles and the cycles of ARB processing on microstructure and mechanical properties of DSS was investigated.The results show that:(1) Comparing with the original materials, the microstructure of ARBed samples was refined, the mechanical properties were improved. But the bonding strength was low; in the tensile test the bonding layers were split. The stress-strain curve showed that when bonding layers split the stress decrease abruptly.(2) Accumulative roll bonding process was performed at1100℃and TiC particles were used to improve the properties of duplex stainless steel. After six cycles of roll bonding, the sheets were made up with64layers of duplex stainless steel and63layers of reinforcing particles, the microstructure of the composites was refined, austenite and ferrite were distributed along the rolling direction. The hardness and tensile strength of the composites were enhanced and the bonding strength was improved by the ceramic particles. Particles clusters were found in some part of the fracture surface of the samples.(3) In order to achieve a uniform distribution of reinforcement particles, cross-roll accumulative roll bonding (CR-ARB) was used to produce duplex stainless steel matrix composites. The samples were rotated90°in every cycle. The microstructure of the composite had a good degree of homogeneity, the banded structure which was very obvious in normal accumulative roll bonding processing turned into a homogeneous structure. The bands of austenite were torn up and distributed in the ferrite uniformly. The mechanical properties of the samples were enhanced, bonding strength was very good. Particles distributed uniformly as well.(4) Micron-sized TiC and nano-sized Al2O3were mixed in a volume ratio of4:1. The composites reinforced by mixed particles were produced by cross-roll accumulative roll bonding. The microstructure of the mixed particles reinforced composites was fine and had a good degree of homogeneity in particles distribution. The bonding strength of each layer was high. The results of hardness test and tensile test showed that the mixed ceramic particles had an excellent effect in reinforcing duplex stainless steels. The hardness and tensile strength were almost twice as high as the raw material.