Effect of orbital automatic welding on the weld metal mechanical properties in API 5L X65 natural gas transmission pipe

摘要

API 5L-X65 steel pipes with a 17.5mm wall thickness and 762mm in outer diameter were welded using an orbital automatic welding process. Flux Cored Arc Welding (FCAW) and Gas tungsten Arc Welding (GTAW) consumables were utilized to evaluate automatic the welding process. Manual weld were deposited using GTAW with ER70S-G filler metal for the root pass and Shielded Metal Arc Welding (SMAW) with low hydrogen E9016-G electrode for the remaining passes. Charpy impact test, CTOD (Crack Tip Opening Test) test and micro-hardness test on the weld metal were carried out and the effects of weld metal composition and microstructure on the weld metal toughness were investigated. The filler metals that have superior fracture toughness were E80T1-K2 and E71T-1 of FCAW process and ER80S-G of GTAW process. The foller metals that have proper hardness were E80T1-K2 and E71T-1 of FCAW process.