Continuous and active works have been going to develop 700°C A-USC (Advanced Ultra Super Critical) power plants in Europe, United States and also Japanese national project has launched in 2008. In this new Japanese project Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is one of the candidate materials for boiler tube and pipe as well as Ni based alloys such as well-known Alloy617, Alloy263 and Alloy740. The most important issue in boiler fabrication is the welding process of these alloys and long-term reliability of their weldments. Authors investigated the weldability of HR6W thick-wall pipe. The integrity of the weldment was confirmed with metallurgical investigation, mechanical testing and long term creep rupture test. It is proved that the narrow gap HST welding procedure can meet the requirements for Ni based or Fe-Ni based alloys and provides excellent strength properties.

FeAl intermetallic compound coating was prepared by cold spraying a mechanically alloyed Fe(Al) alloy powder followed by post-spray annealing at 950°C. The high-temperature abrasive wear test was carried out for the annealed cold-sprayed FeAl at a temperature range from room temperature to 800°C. The high temperature abrasive wear of a heat-resistant stainless steel 2520 was performed for comparison. The results showed that the annealing treatment of the as-sprayed Fe(Al) alloy coating at a temperature of 950°C results in the formation of dense FeAl intermetallic compound coating with no particle boundaries. It was found that with the increase of the test temperature the wear rate of the stainless steel increased at the temperature higher than 400°C, while the wear rate of cold sprayed FeAl coating tended to decrease at the temperature higher than 400°C. The high temperature abrasive wear resistance of the cold-sprayed FeAl intermetallic compound coating increased with the increase of the abrasive wear temperature in a temperature range from 400°C to 600°C and changed little in the temperature range from 600°C up to 800°C. The wear resistance of cold-sprayed FeAl coating was higher than that of heat-resistant 2520 stainless steel under 800°C by a factor of 3.