Development Of X60 Steel And Heat Treatment Technology For Composite Plates With Explosive Welding

In recent years,as the high acid corrosion of oil-gas fields have been found and mined,most of the anti-corrosion technologies are so difficult to balance the economy and reliability,such as the addition of inhibitor,cathodic protection,anti-corrosion coating in pipe and so on.N08825/X60 explosive composite plate,can not only combine the high corrosion resistance of nickel based alloy 825 and high strength of X60,but also greatly reduce the cost of production.Because the technical specification which is applicable to the procurement of N08825/X60 explosive composite plate for sales gas production facilities with capacity of 30 BCMA(Billion Cubic Meters Per Year)on the Galkynysh Gas Field in Turkmenistan is so strict.There are not mature technologies and achievements.So the development of the explosive composite plate which can meet the requirements of the technical specification is imminent.In this paper,the influence of annealing process on the interfacial hardening layer and interfacial shear strength of N08825/X52 composite plates with explosive welding was studied,and the problem of high hardness near the combined interface was solved.Then,the effects of annealing temperature and holding time on microstructure and properties of X60 steel were studied by optical microscope,scanning electron microscope,transmission electron microscope,tensile test and impact test.Finally,the effect of critical region quenching process on interface hardening layer and properties of the test steel was studies by optimizing the chemical composition of X60 steel and the heat treatment process.And,the chemical composition and heat treatment process of X60 steel plate used for N08825/X60 explosive composite plate were identified.The results show that:(1)The main reason for the increase of hardness near the interface is the work hardening caused by plastic deformation during the explosion process.By recrystallization annealing,the hardness of carbon steel near the interface can be reduced completely,and the reasonable control of annealing temperature is the key.For the N08825/X52 explosive composite plate,the most reasonable annealing temperature is about 600?.After annealing treatment at 500?640?,there is no hard brittle intermetallic compound in the interfacial diffusion zone.So,the interfacial bonding is good,and shear strength is much higher than the technical requirements of 250 MPa.As the annealing temperature increases,the shear strength of the annealed plate slowly decreases.(2)With the increase of annealing temperature,the impact toughness and strength of the carbon steel are improved by the multiple factors such as precipitation of micro alloying elements,tempering of M-A island,internal stress release and so on.But,the yield ratio of the test steel is more than the technical requirement(Rt/Rm?0.9)during the annealing at 600 ? 640?.Therefore,it is necessary to re-optimize the chemical composition and heat treatment process of the test steel.(3)The results of the new component test steel show that the precipitation strengthening effect can be effectively reduced after annealing at 600? by adjusting the content of the micro alloying elements and other conventional elements of the carbon steel,which leads to obtain a lower yield ratio.Adopting the process of "critical region quenching at 800? + explosive welding + tempering at about 600? ",can not only eliminate interfacial hardening layer,but also control the soft and hard phase in microstructure to obtain a lower yield ratio.Finally,the all properties of explosive welded N08825/X60 bimetallic plate can meet the requirements of the project.