A Study Of Temper Embrittlement For Hot-Wall Hydrogenation Reactor Material 2 1/4Cr-1Mo Steel

In petroleum refining industry, hydrogenation technology is widely used. It helps improve the quality of petroleum products, reduces waste and increases the yield. Therefore, this technology receives much attention in oil refining industry all over the world and develops quickly. Hydrogenation reactor is the key equipment in hydrogenation unit, which has two types: cool-wall reactor and hot-wall reactor based on the temperature of hydrogenation reactor shell under working condition. This paper focuses on the hot-wall type made from 21/4Cr-1Mo steel, which undergoes obvious high temperature temper embrittlement after a period of service. Therefore, the research about the temper embrittlement of material is of great importance for the safe running of hydrogenation unit.The hydrogenation cracking unit of the Aromatic Plant in Yangzi Petrochemical Company (YPC) was put into production in October, 1989. There were 4 test blocks with welded joints at the inside bottom of reactor. The material of test blocks is the same as that of reactor shell. One test block was taken out in 1995(after 50,000 hours in service) on which most of research work was done. The results demonstrate that some damage has been done to the material. The specimen of present paper is a test block in DC101A that has been in service for 12 years. The damage of material is further studied based on this test block.The main contents in present paper are as follows:1. Temper embrittlement test was made on the test block serviced for 12 years. By impact test of base material and weld joints, the curves of impact energy with test temperature and material temper embrittlement damage were obtained. Based on fracture macroscopical appearance of test block impact specimen, transition temperatures of fracture appearance were gained.2. The test data of the test blocks serviced for 5 years and 12 years are compared and analyzed. The results showed that the test block underwent obvious temper embrittlement. The temper embrittlement increased with the service years, while sampling location had little influence on the temper embrittlement.