Study On Microstructure And Properties Of Super Strength Upset Type Hollow Sucker Rods

The current number of rod pumping Wells is increasing in our country,and the well depth is also higher than before.So the general strength of sucker rod can not meet the conditions.In this situation,it is necessary to research the super strength hollow sucker rods.In this paper,The microstructure and mechanical properties of test steel were investigated by means of thermal simulation,mechanical properties test,microscopic analysis and computer simulation technology.By changing the process parameters,it could Make the D grade of steel to improve a level.Effect of different heat treatment process on the microstructure and properties of test steel were researched.Analyzing the influence of microstructure on mechanical properties and establishing the relationship between the performance,microstructure and properties.The main conclusions are as follows:(1)The results show that under different quenching temperature,martensite can be obtained.With the increasing of heating temperature,the trend of strength index is up.When the heating temperature is 900?,the strength and toughness are both good.(2)The results show that with the increasing of cooling rate,the trend of strength index is up while plastic index is down.The test steel was cooling by water and obtained certain amount lath martensite.The test steel is good performance because of the martensite of polydirectional distribution,dislocation of high density and fine effective grain.(3)The different microstructures and properties of original organization with quenching and tempering method are both good performance.But the number of quenching is not necessary to get good comprehensive mechanical properties.On the contrary it will produce tempering brittleness.(4)The results show that with the increasing of tempering temperature,the trend of tensile strength,yield strength and strength index is down.But the strength is higher than the original material.The trend of percentage elongation after fracture and uniform elongation is up.(5)Considering both strength and plastic of grade D sucker rod steel 20 CrMo,the test steel should be treated with secondary quenching before 550 ?high temperature tempering process and the sucker rod properties is reach for class H.(6)By using Deform-3D software,the forming model of the hollow sucker rod coupling and rod head was established.Accroding to the process parameters of simulation calculation,we obtained the qualified forming products.