Q460C高强钢材对接焊缝的低温力学性能试验

Experimental study on the mechanical properties of butt weld of Q460C high-strength construction steel at low temperature

对我国目前研制的Q460C建筑高强钢材的焊接钢板进行低温拉伸试验,得到屈服强度fy、抗拉强度fu、断面收缩率ψ、断后伸长率δ、屈强比等力学性能随温度的变化规律,同时计算了Q460C焊接接头的温度敏感系数,并对断口进行了扫描电镜分析。研究结果表明:随温度下降,其抗拉强度和屈服强度均有所提高,但ψ和δ都有不同程度下降,并与其母材进行比较分析,表现出其力学性能低于母材,表明Q460C焊接钢材有较大的低温冷脆倾向;得到预测其低温下屈服强度、抗拉强度和屈强比的公式;在低温地区中使用高强结构钢材Q460C时要考虑低温冷脆。

The tensile tests studying the mechanical properties of 14 mm Q460C steel,the high-strength constructive steel were carried out at low temperature,whereby the yield strength,tensile strength and the elongation were studied at rupture,area and yield ratio reduce with the decrease of temperature.Meanwhile,the mechanical properties of non-welded Q460C steel were comparied.Temperature sensitivity coefficients of the welded Q460C steel were calculated and the strengths at low temperature was forecasted.Moreover,the scanning electronic microscope of the tensile specimen fracture surfaces were analyzed.The results show that the welded Q460C steel is more likely to brittle fracture.With the decrease of the temperature,the strength increases,and the yield ratio also raises,but the elongation at rupture and reduction of area decrease,which meanes its plasticity is worse.Therefore choosing Q460C steels as constructional materials at cold area,its cold brittleness should be considered carefulls.