| In recent years, with the development of the industry and the improvement of the people's life, the stainless steel is widely used due to its best anti-corrosion property and better surface finish, and its potential consumption is increased year by year. However, due to the stainless steel contains many rare element metals just like Cr, Ni and Mn, its price is very high. The stainless steel - low carbon steel composite materials could economize the content of Cr and Ni about 70-80%, so its price is very dominance in the consumption market. Therefore, the stainless steel- low carbon steel composite sheet is pay more attention during it comes from the industry, and its manufacture technology is also focused by the researches all over the world.In this paper, the 304 stainless steel- IF steel composite sheet is successfully produced by the CGDS and cold rolling technology. Firstly, the effect of the sprayed parameter on the particle deposition, coating microstructures and performance was investigated. The results showed that increasing the gas temperature and pressure could directly increased the particle deposition, due to increasing gas temperature could not only increase the particle's impacted velocity but also soft the particles, so the increase of gas temperature could decreased the particles'critical deposition velocity. Increasing gas temperature and pressure could decrease the porosity of the coatings, and also enhanced the cohesive strength of the coating. Moreover, the gas temperature has bigger effect to the cohesive strength than the gas pressure; it could increase the cohesive strength from 56MPa in 450℃to 94MPa in 750℃. And the gas pressure could only increase about 14MPa form 2.0 MPa to 3.3 MPa.Both of the experimental and simulation method was used to investigate the particle deposition characters on the substrate surface. The result shows that the bigger impacted velocity could cause the thicker area of the metal jetting around the particle surface, and the impacted particle became more flatten. The simulated method investigated that the deformation behavior of both particle and substrate, the evolution of maximum plastic strain, the occurring of adiabatic shear instability and critical velocity. It is analyzed that the distortion behavior of both particle and substrate, the evolution of maximum plastic strain and characteristic curve of characteristic node.Secondly, the microstructure and the property were also investigated. The results showed that the as-sprayed coating was made up of many distorted particles, and the interface between the coating and substrate was just mechanical interlocking. Due to the work-hardening effort the microhardness of the coating was 1.9 fold of the original powder, and the hardness value is about 343HV0.2.The ultimate strength of the coating is about 94 MPa and the fracture character is brittle. During the cold rolling process, the cohesive strength of the cold sprayed 304 stainless steel coating is too low to be cold rolled. Microcracks are formed in the as-sprayed coatings and run perpendicular to the rolling direction. The spacing between these cracks decreases with the increase of rolling reduction. It is also found that the initial crack generates in the surface of the coating and propagates from the surface to the interface along the weakly bonded particle's interface. And at last the coating was ruptured from the substrate.Then the post heat treatment was used to optimize the coatings'microstructure and properties. It also investigates the influence of the heat treatment on the microstructure and properties, and illustrates the diffusion mechanism between the particles. The results showed that annealing treatment had a great contribution to enhancing the bonding strength of the particles, cause the recrystallization and healing up the incomplete interfaces between the deposited particles under certain annealing conditions. And the diffusion interface between the coating and substrate was increased from 7μm at 850℃to 47μm at 1200℃. In addition, the coating ultimate tensile strength increased from 73 MPa for the as-sprayed coating to 407 MPa for the heat treated coating. The coating microhardness decreased from 343 HV0.2 for the as-sprayed coating to 195 HV0.2 for the heat treated ones at 1200℃. Fracture morphology of the coatings also revealed that the as-sprayed coating performed a brittle type and the annealed ones showed a rather plastic type.Finally, the deformation behaviors of the heat treated 304SS coatings and the substrate by cold rolling were investigated. The coordinated deformation mechanism of coating/substrate system was also discussed. The results indicate that heat treated temperature and the initial thickness ratio between the coating and substrate were significantly influence the deformation of the composite trip during cold rolling process. Increasing the heat treatment temperature increase the coordinate deformation ratio of the coating and substrate. When the heat treated temperature achieved to 1100℃and 1200℃, the coordinate deformation behavior get the best. When the cold rolling reduction is minor than 40%, the coordinate deformation ratio was smaller than 0.55, and the coordinate deformation ability is poor. When the cold rolling reduction was higher than 50%, the coordinate deformation ratio was similar to 1 at the temperature 1100℃and 1200℃, the coordinate deformation ability is well. When the initial thickness ratio is 2%, the coating and the substrate shows rather good coordinate deformation behavior and the coordinate deformation ratio was similar to 1. When the initial thickness ratio is 4.5%, the coordinate deformation ratio was smaller than 0.8 at lower than 40% rolling reductions. When the rolling reduction is higher than 40%, the coordinate deformation ratio was similar to 1. If the initial thickness ratio is about 15% or 50%, the coordinate deformation ratio is lower which is below 0.6 or 0.3; the coating could hardly coordinate deformed with the substrate.
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