Grain Growth Kinetic Model of Coarse Grain Heat-affected Zone for X80 Pipeline Steel

Thermal simulating technology was adopted to study grain size and the precipitates distribution of CGHAZ for X80 pipeline steel with different welding condition.The expermiental results showed that the austensite grain with mean size of about 30-40 μm has uniform size distribution.In addition,the grain was fine when the precipitates have small size and large quantity.Considering the pinning effect of the precipitates,the grain growth kinetic model of CGHAZ for X80 pipeline steel was established based on experimental data through introducing the limiting grain size.