激光增材制造合金钢力学性能超声纵波定量无损评价

目的研究采用超声无损检测方法定量评价激光增材制造合金钢的布氏硬度和抗拉强度。方法通过搭建高精度超声纵波声时测量系统,采用脉冲反射回波法测量不同热处理状态激光增材制造24CrNiMo合金钢标定试件的超声纵波传播声时,计算超声纵波声速;在考虑激光增材制造合金钢各向异性和成形界面对超声纵波传播特性影响的基础上,研究标定试件微观组织对超声纵波声速的影响,建立标定试件激光扫描方向布氏硬度、抗拉强度、微观组织与超声纵波声速之间的映射关系。结果建立了超声纵波评价硬度及抗拉强度的标定模型,并对标定模型预测误差进行验证,硬度及抗拉强度标定模型预测误差均小于10%,满足工程应用误差指标要求。结论采用超声纵波声速可以实现激光增材制造合金钢硬度及抗拉强度的定量评价与表征。

Nondestructive Quantitative Evaluation on Mechanical Property of Alloy Steel by Laser Additive Manufacturing via Ultrasonic Longitudinal Wave

The paper aims to quantitatively evaluate Brinell hardness and tensile strength of alloy steel by laser additive manufacturing through ultrasonic nondestructive testing. The high-precision ultrasonic longitudinal wave measurement system was set up. Ultrasonic wave propagation time of different heat treated 24CrNiMo alloy steel calibration specimen by laser additive manufacturing was measured by the pulse reflected echo method to calculate the ultrasonic velocity. In the measuring process, based on the effects of alloy steel anisotropy and forming interface on longitudinal wave propagation characteristics, the effect of different microstructure on ultrasonic longitudinal wave velocity were studied. The mapping relationships among Brinell hardness, tensile strength, microstructure and ultrasonic longitudinal wave velocity of the calibration specimens on laser scanning direction were obtained. The calibration models for evaluating the Brinell hardness and tensile strength were established and verified. The prediction error was less than 10%, which met the error requirement of engineering applications. The hardness and tensile strength of alloy steel by laser additive manufacturing can be quantitatively evaluated by ultrasonic longitudinal wave velocity.