Study on Process and Property of N80-1 Upset Tubing

Described here are the basic processes for producing the N80-1 upset tubing,and analyzed are the metallographic structure and the properties of the upset end,the transitional section and the pipe body proper of the said tubing.The result via the analysis shows that the metallographic structures at different positions are different i.e.,coarse pearlite and ferrite network are found at the upset position,abnormal dual-phase zone heated microstructure at the transitional section,while fine pearlite and even dispersed ferrite are found with the pipe body proper;the properties of the upset end,the transitional section and the pipe body proper are different obviously,the hardness and tensile properties decreased from the upset end to the transitional section to the pipe body proper,whereas the impact toughness increased following the same order.After the normalizing,the metallographic structures at the said different positions all get fined and homogenized,and are almost the same,while the ferrite content is significantly increased;their strength,hardness and impact toughness are tending to unanimity,moreover the overall strength and hardness are obviously decreased,and the impact toughness greatly increased.