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本文研究了蠕变断裂韧性对二种低合金耐热钢蠕变裂纹开裂和扩展的影响。试验表明:随着蠕变断裂韧性提高,抗蠕变裂纹开裂和扩展能力增加。材料呈韧性或脆性状态时,蠕变裂纹萌生和扩展过程不同。韧性状态时,裂纹为穿晶和晶界二种混合形式:穿晶裂纹可在晶内碳化物处发生,或在晶界上形核后向晶内扩展,晶界裂纹仍是由晶界上空洞形成和相互连接而成,裂纹可沿晶界和晶内扩展,但不连续。脆性状态时,裂纹沿晶界发生,它是由晶界形成空洞和相互连接而成,扩展仅沿晶界发生。
In this paper, the effect of creep fracture toughness on creep crack initiation and propagation of two kinds of low-alloy heat-resisting steel was studied. Experiments show that creep rupture tenacity increases with increasing creep rupture toughness. When materials are ductile or brittle, the initiation and propagation of creep cracks are different. In the ductile state, the crack is a mixture of transmutation and grain boundaries: the transgranular crack can occur at the intragranular carbide or nucleate and then expand into the grain after grain nucleation, and the grain boundary crack is still caused by the grain boundary Cavity formed and connected to each other, the crack along the grain boundaries and intragranular expansion, but not continuous. In the brittle state, cracks occur along the grain boundaries, which are formed by the formation of voids and interconnections in the grain boundaries, extending only along the grain boundaries.