ABSTRACT
High-temperature service was investigated by a metallographic microscope, a scanning electron microscope, an X-ray diffractometer, and tensile and bending tests. Microstructure and mechanical properties of HR3C steel weld joints for a 20,000 h ultra-supercritical unit. The results show that a large number of strips and granular M23C6 precipitates are formed in the weld metal of HR3C steel after long service at high temperature, and austenite grains grow in the welding heat affected zone, forming the plate M23C6 phase near the grain boundary. The tensile and bending test results show that HR3C steel welded joints show an obvious tendency of aging embrittlement after high-temperature service.
