316LN austenitic stainless steel stress corrosion cracking of welded joints
|School||Shanghai Jiaotong University|
|Course||Nuclear energy and technology engineering|
|Keywords||Austenitic stainless steel 316LN Cold Heat treatment TIG welding MIG welding Welded joints Stress corrosion cracking Intergranular corrosion|
316LN austenitic stainless steel was selected as the third-generation reactor technology AP1000 main pipeline , timber, its mechanical properties and corrosion resistance in the country has done a lot of research, got some valuable conclusions . However, due to experimental difficulties, data processing capacity, experimental reasons for higher environmental requirements , domestic austenitic stainless steel and welded joints for stress corrosion cracking little quantitative research . The main subject for 316LN austenitic stainless steel base material and welded joints resistance to intergranular corrosion and stress corrosion cracking performance of quantitative research . The factory materials and different forms of variable annealed cold rolled , while using GTAW (TIG) and GMAW welding (MIG) welded joints produced . With the treated base material and welding material, compact tension specimens in boiling saturated magnesium chloride solution for constant load tension test . By DC voltage drop method to test the stress corrosion crack growth rate , resistance to stress corrosion cracking studies . Live again by electrochemical potentiodynamic method research resistance to intergranular corrosion. Cold rolling and cold rolling the material under heat treatment process experimental results showed that: cold rolled heat-treated material resistance to stress corrosion cracking is stronger than cold-rolled material , the same kinds of materials under rolling deformation process the greater the more resistance to stress corrosion cracking poor. Cold heat treatment material susceptibility to intergranular corrosion than cold-rolled material , the same kinds of materials under rolling process variables greater susceptibility to intergranular corrosion is higher. TIG and MIG welding of welded joints under Experimental results show that : 316LN welded joints of the overall resistance to stress corrosion cracking , MIG weld in TIG welding , 80% Ar 20% CO2 shielding gas MIG welding ( process 1107 ) better than 100% CO2 shielding gas MIG welding ( process 1108 ) . Overall susceptibility to intergranular corrosion , TIG welding is higher than MIG welding , process technology 1108 than 1107 . Under the same welding process , 316LN welded joints in different regions of resistance to stress corrosion cracking , the weld zone the worst , the best heat-affected zone , fusion zone centered ; resistance to intergranular corrosion , weld zone is best , the worst heat-affected zone , fusion zone centered. The conclusion is the main channel of the third generation of nuclear power plants manufacture, installation provides a certain reference .