Optimization of submerged arc welding heat affected zone toughness in X-120M line pipe steel
In view of the ever-increasing demand for energy and ever increasing operating pressure of line pipe, it is very essential to develop high strength steel and production technology for manufacturing the line pipes of high strength of level to X-120M. Recent experiments show that the grade (X- 80M) with respect to grade (X-70M) could give investment cost saving of pipe line construction project. if we use X-120M steel line pipes, the cost saving is much higher. Therefore, economic transport of gas from remote sources is an important consideration in today’s global economic environment. To solve these challenges, a high strength grades, large diameter line pipe of X-120M strength level through J-C-O-E technique has to be developed. The J-C-O-E longitudinal double submerged arc welding (LDSAW) of X- 120M line pipe has major challenge to establish the toughness for heat affected zone (HAZ) at theX-120M strength level, as the SAW welding is high heat input welding process. So the maintaining the strength and toughness at the strength level of X-120M of heat affected zone (HAZ) is very critical as the cooling rate is very high.
