Abstract
This article investigates the welded joints of HSLA Q550 without preheating and post-heating treatment process. Tensile test, bending test, low temperature impact test, and the impact fractures and joint microstructure observation and analysis are used.The test result shows that the welded joins achieves equal strength with base metal. The average values of the welded joints impact absorbed energy at -20 °C are greater than 40J and at -40 °C its average values are greater than 27J, thus the low-temperature impact energy joint can meet the service requirements of hydraulic support. It shows that choosing proper welding material, developing reasonable welding and post-heating treatment process can cancel the preheating process of Q550 steel welding. © (2013) Trans Tech Publications, Switzerland.