Evaluation of tearing instability behaviour of carbon steel for nuclear primary system.

用LTCT试件进行了单调加载和循环加载下的弹塑性断裂韧性和撕裂失稳试验。这些试验中使用的材料是为核一次系统制造的碳素钢管。从L-C方向的管道中取出侧槽深度为2.5 mm的LTCT试件。主要结论如下：(1)该材料具有很高的断裂韧性，约为&lt；J_(Lc)&gt；=0.96Mj/&lt；m^2&gt；(2)&lt；J_(Lc)&gt；、&lt；Delta_(Ic)&gt；、J-R曲线、&lt；T_J^(Mat)&gt；和&lt；T_(Delta)^(Mat)&gt；随温度升高而减小。但变形速率对它们的影响不大。(3)不稳定时的临界值&lt；J_(Inst)&gt；与测试系统的顺应性有关，但随温度的升高而减小。(4)循环荷载作用下，应力比R对&lt；J_(Inst)&gt；影响不大。当R=0.1时，&lt；J_(Inst)&gt；的值略高于R=-0.1的值。(5)R=0.1下的&lt；J_(Inst)&gt；几乎等于单调载荷下的&lt；J_(Inst)&gt；。(6)&lt；J_(Inst)&gt；在单调载荷作用下表现出很小的散布，这种散布可以用威布尔分布函数来表示。

Elastic-plastic fracture toughness and tearing instability tests under monotonic and cyclic loading have been made by using lTCT specimens. The material used in these tests is a carbon steel pipe made for a nuclear primary system. lTCT specimens with side groove of 2.5mm in depth is extracted from the pipe in L-C direction. The main conclusions are as follows.(1) This material shows very high fracture toughness of about <J_(lc)> =0.96Mj/ <m^2> . (2) <J_(lc)> , <delta_(ic)> , J-R curve, <T_J^(mat)> and <T_(delta)^(mat)> decrease with increasing temperature. However, deformation rate has a little effect on them. (3) Critical value at instability <J_(inst)> shows on dependence on the compliance of testing system, however it decreases with increasing temperature. (4) Stress ratio R has a little effect on <J_(inst)> under cyclic load. <J_(inst)> under R=0.1 shows a little higher value than that of R=-0.1. (5) <J_(inst)> under R=0.1 is almost equal to the <J_(inst)> under monotonic load. (6) <J_(inst)> under monotonic load shows a very little scatter, and the scatter can be expressed by the weibull distribution function.