由于碳钢材料在许多领域有着非常广泛的应用,所以研究碳钢的无损探伤规律具有很重要的现实意义.为探究碳钢在脉冲红外热成像无损探伤中的规律,特设计A、B两种标准试件,利用脉冲红外热成像技术对两种标准碳钢试件中缺陷的大小和深度进行了定量化研究.研究结果表明,测量近表(l＜1.8 mm)小缺陷的大小时,应选择在热脉冲作用后约0.3 s进行,此时测量误差比较小,并且对深度小的缺陷进行大小的测量要比深度较大的缺陷困难.对于深度较大的缺陷,只要红外热图像清晰,测量误差都比较小.测量缺陷深度时,当缺陷直径大于6 mm时,测量误差比较小.当缺陷直径小于6 mm时,误差比较大,甚至无法探测到缺陷.由于热扩散,测量缺陷的深度应选择在热脉冲作用后的短时间内进行,以保证红外热图像的清晰度,减小测量误差.

Carbon steel is widely used in many fields.It is of great importance to study the behavior of carbon steel in nondestructive testing.To investigate the behavior of carbon steel in thermal pulse video thermography nondestructive testing,two standard carbon steel test-pieces are made.The sizes and depths of defects in two standard carbon steel test-pieces are studied by thermal pulse video thermography.The results show that for the purpose of minimizing errors of size measurements the testing time should be chosen at about 0.3 s after the thermal heat flux applied to the specimen with defects of smaller depths （l〈1.8 mm ） and it is more difficult to measure the size of shallower defect than that of deeper defects.For the defects with diameters larger than 6 ram,the depth measurement errors are usually small if the thermograms are in high contrast.If defect diameters are smaller than 6 mm, the depth measurement errors are usually more than 10% .To determine the depth of the defect it should be performed shortly after the thermal flux applied to the test-piece to avoid the blurring of the thermal images due to heat diffusion.