The Research On Valve Stem Forging Process Of A638-660 Super Alloy

Oil hydrogenation technology is an important process measure in oil refining ?modification and heavy oil's processing.In the hydrogenation equipments,the valves that used in high temperature and in S ? H2 S environments,the stem material is A638-660.A638-660 is an iron base super alloy.The article is focused on the 3”2500LB globe valve stem forging which material is A638-660 super alloy.As the stem forging is unqualified in UT process,there are cracks in shaft junction of the stem.In order to solve this problem and to ensure the stem forgings are qualified in the actual production,the article studied the reasons of crack and the forging process,through a series tests and experiments,combined with finite element simulation.The main research methods and contents are as follows:?1?According to the metallographic analysis?Scanning electron microscopy?SEM?analysis?energy spectrum analysis?EDS?and mechanics analysis,the reasons of the 660 stem are studied.The results show that the cracks in the stem are not for raw material and heat treatment,but due to the forging process and the forging manner.?2?In the conditions of 50% deformation,strain rate of 0.01S^-1,1S^-1,10S^-1,temperature range of 900?¹200?,the hot compression experiment of A638-660 super alloy has been tested on Gleeble-3500 D thermal simulation testing machine.Through the experiment,the article studied the flow stress behavior of 660 super alloys and got the constitutive equation and the Z parametric equation.The constitutive equation is verified.?3?According to the actual production equipment conditions and combining A638-660 alloy forging process parameters,design the forging process card.Actual production tested according the forging process card,record some dates.By using DEFORM-3D simulation software;simulate the whole process of the forging process.At the same time through the simulation software,compare two different forging processes,so as to design the most appropriate forging process.To provide theory basis and reference for practical production.