【摘要】 在Gleeble 2 0 0 0试验机进行了Q345c hq微合金钢 (% ) :0 11C 1 2 7Mn 0 0 2 0P 0 0 0 7S 0 0 4Cu 0 0 2Nb 0 0 1Ti的连铸坯在 6 0 0～ 10 5 0℃、应变速率 5× 10 - 1 s至 5× 10 - 3 s下的高温拉伸试验。结果表明 ,应变速率为 5 0× 10 - 1 s时 ,Q345c hq钢的脆化温度为 70 0℃左右 ,当应变速率降低到 5 0× 10 - 3 s时 ,钢的脆化温度范围扩大到 6 0 0～ 90 0℃。显微组织分析得出 ,70 0℃时在γ晶界形成网状薄膜先共析铁素体 ,成为裂纹源 ,是脆化的主要原因。避免在 6 0 0～ 90 0℃脆化温度区矫直是防止该钢连铸坯产生裂纹的关键措施更多还原

【Abstract】 The elevated temperature tensile test of concasting billet of Q345c-hq microalloy steel 0.11C-1.27Mn-0.020P-0.007S-0.04Cu-0.02Nb-0.01Ti with strain rate 5×10 -1/s to 5×10 -3/s at 600～ 1 050 ℃ has been carried out by Gleeble-2000 system. The test results showed that with strain rate 5×10 -1/s the brittle temperature of Q345c-hq steel was about 700 ℃, and with strain rate decreasing to 5×10 -3/s the brittle temperature range of steel extended between 600～900 ℃. It is obtained by analysis on microstructure that the net like lamellare of proeutectoid ferrite formed along γ grain boundary being crack initiation are main reason of steel brittleness. The key measure to prevent crack formed in concasting billet of the steel is avoiding to straight the billet at brittle temperature zone between 600 ℃ and 900 ℃.更多还原