焊接接头微区力学性能压痕测试系统

Local mechanical property testing system of welded joint using instrument ball indentation technique

焊接接头是一个组织与性能的不均匀体,为了对接头力学性能作出有效评价,采用示值球形压痕技术(IBIT),以步进电动机为动力,用载荷传感器、位移传感器连续获取载荷、位移数据;以触摸屏为操作界面,用PLC进行运动控制和数据处理,研制出压痕性能测试系统,获得被测接头的压痕硬度、弹性模量、屈服强度、抗拉强度、应变硬化指数及表面残余应力.与其他焊接接头力学性能测试方法相比,该系统具有便捷、非破坏、多功能、实时在线检测的特点,尤其适用于工程现场焊接接头微区力学性能的测试.

The welded joint is an inhomogeneous body with abrupt microstructural and mechanical property gradients. In order to evaluate mechanical properties of the welded joint effectively, an indentation property measurement system was developed. As a promising apparatus, a ball indenter was drived by a step motor to produce indentations, while the load applied to the indenter and the depth of the indenter penetrated into the surface of the welded joint were measured continuously with a pressure transducer and a displacement transducer respectively. The whole system was operated through a programmable terminal （PT） with user-friendly interfaces and controlled by a programmable logic controller （PLC） with excellent data acquisition and processing quality. With the indication ball indentation technique （IBIT）, the indentation hardness, youngg modulus, yield strength, ultimate tensile strength, strain hardening exponent and surface residual stress of the tested joint were simultaneously measured. Compared with the conventional standard methods, the present system has such advantages as convenient, non-destructive, multifunctional, online and in-field testing, and especially is suitable for evaluating the local mechanical propertities of the welded joint in engineering site.