25Cr2Ni4MoV合金锻件断裂韧性试验影响因素的研究

Research of Influencing Factors on Fracture Toughness Test Results of Forging Alloy 25Cr2Ni4MoV

利用卸载柔度法对25Cr2Ni4MoV进行断裂韧性试验,对比研究了初始裂纹长度、试样尺寸、试验参数及数据处理方法对试验结果的影响。结果表明:随着初始裂纹长度的增加,测得的断裂韧性值减小,试验中加载所需要的最大载荷也逐渐降低;紧凑拉伸CT25(25mm厚)试样得到的断裂韧性值大于CT38(38mm厚)试样;当加载速率较低(<1.5 MPa·m^(0.5)·s^(-1))时,加载速率变化对试验结果影响不大;当加载速率继续增大时,测得的断裂韧性值减小;随着保载时间的延长,测得的断裂韧性值减小;GB/T 21143-2014和ASTM E1820-2016在钝化线斜率、有效数据判定和拟合曲线方程等方面对数据处理结果影响较大,且前者得到的试验结果比后者要小。

Through fracture toughness tests of alloy 25 Cr2Ni4MoV conducted by single sample unloading compliance method,the influence of following factors on the test results was investigated,such as the initial crack length,specimen size,test parameters and the data processing method,etc.Results show that both the fracture toughness measured and the maximum load applied in the test reduce with the rise of initial crack length.The fracture toughness obtained with CT25（25 mm thick）specimen is higher than with CT38（38 mm thick）specimen.At low loading rate（〈1.5 MPa·m（0.5）·s^-1）,the measured data of fracture toughness is slightly affected by the loading rate,which would reduce when the loading rate is further increased;the longer the holding time is,the smaller the measured data of fracture toughness would be.The main differences between GB/T 21143-2014 and ASTM E1820-2016 lie in such data processing methods as the blunting line,valid data judgment and the curvilinear equation,etc.,and the values calculated with the former standard would be lower than that with the latter one.