高强度无钴马氏体时效钢的晶粒长大及其力学性能研究

Study of grain growth and mechanical properties of a high strength cobalt-free maraging steel

在光学显微镜下,通过LeicaMetalWork软件研究了一种高强度无钴马氏体时效钢(00Ni18Mo4Ti)的再结晶晶粒长大行为及其对力学性能的影响。结果表明,在1073～1473K固溶温度范围内,再结晶晶粒表现出正常长大行为;晶粒增长指数随着温度的升高而增加,晶粒长大激活能保持在170～210kJmol-1;屈服强度与晶粒尺寸符合良好的Hall Petch关系,KIC随着晶粒长大而增加。该无钴马氏体时效钢的屈服强度达到2050MPa时,KIC达到70MPa·m1/2,延伸和面缩率分别达到9%和50%以上,实现了强韧性的良好配合。

Grain growth behavior and its effect on the mechanical properties for 00Ni18Mo4Ti alloy, a high strength cobalt-free maraging steel, have been studied with Leica Metal Work software on the Leica Microsysteme optical microscope. The experimental results showed a normal grain growth behavior at the solution temperature range of 1073 ∼ 1473 K for the experimental steel. The grain growth exponent increases with increasing solution temperature and the activation energy remains in a range of 170 ∼ 210 kJmol-1. The relationship between yield strength and grain size well accords with the Hall-Petch relation, but the KIC increases as the grain grows. A good combination of strength and toughness can be reached for this steel, i.e., YS = 2050 MPa, KIC = 70 MPa &middotm1/2, δ>9% and ψ>50%.