| Stainless steel clad plate is based on carbon steel or low-alloy steel and covered by stainless steel.It is the combination of excellent performance of carbon steel and stainless steel.As with the requirements from industrial environment of stainless steel localized corrosion resistance and comprehensive mechanical performance continue to increase,the traditional 304,316L(austenitic stainless steel)has been unable to meet the industrial requirements,duplex stainless steel with high strength and resistance to chloride stress corrosion resistance of ferrite stainless steel and excellent toughness and weldability of austenitic stainless steel,meets the special needs of chemical engineering,marine engineering and other fields.However,there are obvious differences between the two phases of duplex stainless steel,and it is easy to produce cracks and brittle phases.The hot working process is very complex and the process window is narrow.This paper draws the concept of high temperature alloy pack rolling,puts duplex stainless steel inside two carbon steels,to build a relatively stable thermoforming process environment to solve the deformation difficulties of duplex stainless steel and compound forming problem.In order to ensure the accuracy of results in rolling simulation,this paper researches the flow stress curves of the 2205 duplex stainless steel in the Gleeble thermal / mechanical simulator,and calculates the Thermal conductivity,Heat capacity,Poisson ratio,Thermal expansion coefficient and cooling curve of the 2205 duplex stainless steel through the component of 2205 duplex stainless steel with JMat Pro materials simulation software,then obtains the processing map based on dynamic material model to provide the basis for the determination of the parameters in the rolling experiment process.This paper researched the temperature field,strain and strain rate under different reduction in the rolling process of Q235/2205/2205/Q235 clad plate by the MSC.MARC finite element analysis software,and found that the temperature of 2205 duplex stainless steel does not change in the rolling process.When the reduction is 5%,the compound effect is not good according to the Masuda model.When the reduction reached more than 10%,the compound effect is good.In this paper,the rolling experiment of clad plate with different reduction was carried out.according to the analysis of the interface and 2205 microstructure,the rules can be found that when the reduction is 5%,there is the obvious strip and circular pores and oxides on the interface,when the reduction is 10% and 20%,the number and size of interface oxides decreased significantly,and the holes disappeared.Therefore,the greater the reduction,the easier to crush the oxide film in the metal surface,and the new metal is more likely to produce metallurgical bonding in the rolling process.In order to get better performance of the clad plate,this paper analysed the temperature field of clad plate with heat treatment in rolling process by MSC.MARC finite element analysis software,and researched the influence of different heat transfer coefficient on temperature field of clad plate.According to the cooling curve of Q235 and 2205 duplex stainless steel,there is no brittle phases in 2205 duplex stainless steel while Q235 is of better microstructure assumingly,then the critical thickness of clad plate can be recieved under different heat transfer coefficient,providing the basis for heat treatment process.This paper used the Gleeble thermal/mechanical simulator to study the performance of clad plate in fast cooling and air cooling heat treatment process under different heat transfer coefficient,and researched the microstructure of clad plate under different heat transfer coefficient through OM,SEM and EDS.The results showed that when the temperature of 2205 duplex stainless steel exceeds 500°C after the fast cooling,2205 duplex stainless steel will produce the brittle phase in the heat treatment process,so the temperature of 2205 duplex stainless steel must be less than 500°C after fast cooling.With the temperature of 2205 duplex stainless steel after fast cooling rising from 400°C to 700°C,the amounts of ferrite and pearlite increase on the Q235 side near the interface.So it is ensured that the better mechanical property was obtained in Q235 and the brittle phase does not appear in 2205 duplex stainless steel at the same time.Through the hardness analysis for clad plate after heat treatment,this paper found that the maximum hardness of Q235 appears on the surface and the minimum hardness appears near the interface.The microstructure of Q235 is mainly martensite on the surface,and is mainly ferrite and pearlite near the interface,so the overall hardness of Q235 decreased but the plasticity and toughness increased.With the increasing of the temperature of 2205 duplex stainless steel after fast cooling,the amount of ferrite on Q235 increases so that the overall hardness of Q235 decreased and plasticity and toughness increased. |
PDF Full Text Request