Study On Nuclear Containment Vessel SA738Gr.B Carbon Manganese Steel Weldability And Joint Performance

SA738Gr.B low alloy high strength steel is a main quenched and tempered type of steel used in the manufacture of pressure vessel.It has been successfully applied in the pressure vessel of nuclear island containment vessel which has been introduced by our country as the third generation nuclear power technology.In the process of service the device is subjected to high load and radiation effect,thus enough strength,stiffness,service life and high security are required.Combined with the research status of the pressure vessel steel of nuclear technology and the welding material at home and abroad,this paper comprehensively described the advantages and challenges in using SA738Gr.B in the manufacture of nuclear containment equipment.In this paper,based on the comprehensive test of the mechanical properties of SA738Gr.B steel produced by Shanghai Baosteel,implant test,Y-slit type cracking test and thermal simulation test were adopted to realize the qualitative analysis of SA738Gr.B steel’s weldability;three different welding materials were used to weld SA738Gr.B steel,and post-weld heat treatment under different parameters were done on the welded joints of part of flux-cored wire and solid wire;by detecting the low-temperature impact performance and bending performance of the joint,the optimal welding procedure and post-weld heat treatment parameters were selected,which provides systematic data for the nationalization of containment vessels.The main results were as follows:1、With strict control of S and P impurities,SA738Gr.B steel plate possesses good mechanical properties and crack-resistant performance,which meets the design performance requirements of CV containment in ASME standard.2、SA738Gr.B steel possesses excellent weldability.After welding,when the welding cooling speed t8/5 is controlled within 10s～15s,the welding heat affected zone could result in better low temperature impact toughness.3、Compare the test results of three different kinds of welding materials.The results indicates that when the preheating temperature is not lower than 100℃,the stretching and bending performance of both as welded samples and post-weld heat treatment samples are qualified,and the-29 ℃,-45 ℃ impact toughness is good;the impact toughness of post-weld heat treatment joints is lower than the standard,which may due to the excessive welding line energy and the presence of inclusions that distribute along the column crystal grain boundaries or bainite ferrite grain boundaries.4、ER90S-G solid wire,E91T1 flux-cored wire and E9018-G-H4 welding rod were adopted to weld SA738Gr.B steel plate,and the macroscopic and microcosmic performance of welded joints were tested.Through experiment,the optimized technological parameters of three kinds of materials in terms of mechanical properties were obtained.