Experimental research for effects of low temperatureon fracture toughness J_(IC) of structural steels
WU Yan-min, WANG Yuan-qing, SHI Yong-jiu, JIANG Jian-jing(Department of Civil Engineering, Tsinghua University , Beijing 100084, China)
Toughness of structural steels is getting worse as temperature drops, and structural steels are liable to brittle fracture. Fracture toughness J_(IC) of three main structural steels(Q235A,16Mn and 15MnVq)of four thickness (12,24,36 and 48 mm) is measured at five temperature (20,-10,-30,-50,-70 or -65 ℃). The main trend is that J_(IC) of structural steel decreases as temperature drops or thickness increases. Curves of J_(IC) to temperature and J_(IC) to thickness are "S" shapes, which are composed of three parts: upper platform, transition area and lower platform. J_(IC) varies slowly at upper platform and lower platform, while drops rapidly in transition area. In some cases, J_(IC) will increase at upper platform as temperature drops or thickness increases.