10Ni3MnCuAl 模具钢沉淀析出对其动态断裂韧性的影响

测定了沉淀硬化型模具钢１０Ｎｉ３ＭｎＣｕＡｌ在不同加载速率ｖ０下动态断裂韧性Ｋ１ｄ．试验结果表明，随着ｖ０的提高，Ｋ１ｄ降低．ＳＥＭ断口观察揭示，随冲击加载速率的提高，断口形式由韧窝准解理逐渐转变为沿晶准解理形貌．理论研究结果表明，Ｋ１ｄ与裂纹尖端塑性区内参与微裂纹形核的第二相粒子有关．被激活而参与微观断裂的沉淀析出物越多，Ｋ１ｄ越小．透射电镜的微结构分析显示，标准时效（４ｈ）或初时效（１０ｍｉｎ）状态下，其沉淀析出物为大量弥散的金属间化合物Ａｌ３Ｎｉ．沉淀析出物的数量、形态及尺寸分布是影响动态断裂韧性的主要原因．

Influence of Precipitation on Dynamic Fracture Toughness of 10Ni3MnCuAl Die Steel

The dynamic fracture toughness K 1d of the precipitation hardening die steel 10Ni3MnCuAl is tested under different impact velocities v 0.The test results show that the K 1d value decreases with the increase of v 0 and the SEM fractographs change gradually from dimple plus quasi cleavage to intergranular morphology.The theoretical analysis shows that the dynamic fracture toughness K 1d is rela ted to the number of the precipitate which takes part in the nucleation of microcracks in the plastic region of the crack tip.The decrease of the K 1d is associated with the increase of the activated precipitates amount.The dispersed precipitates are identified as Al 3Ni intermetallic by means of TEM analysis under standard aging condition (4 h) or initial (10 min).The dynamic fracture toughness K 1d is mainly affected by the amount,morphology and size of the precipitates.