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在机器制造工业中,电镀(镀铬、镀锌等)工艺是用得相当普遍的。钢铁材料在电镀过程中,常因处理不当,造成零件强度和韧性下降,甚至镀后一段时间还会产生裂纹,给产品质量带来严重的后果。 材料的机械性能决定于材料的化学成分和内部组织结构。当材料化学成分一定,各种性能参数与组织结陶之间有其特定的规律,对钢铁零件电镀脆性而言,其电导率与电镀之间的规律,便可成为无损测试的依据。 1 测试原理 影响材料电导率变化的因素很多,但都与组织结构有关,并受其控制。由于材料组织结构的变化,导致自由电子运动状态发生变化而影响电导率变化。其影向因素如下: 1.1温度的影响 材料温度升高,点阵运动加剧,材料电阻增大,于是季节变化,测试温度的变化也会引起电导率的变化。不过,在实际测试时,仪器,试块和被测工件处于同一
In the machine building industry, electroplating (chrome plating, galvanizing, etc.) is quite common. Steel materials in the electroplating process, often due to improper handling, resulting in parts strength and toughness decreased, or even after plating for some time there will be cracks, the product quality has serious consequences. The mechanical properties of a material depend on the chemical composition and internal structure of the material. When the chemical composition of the material is certain, there is a certain law between the various performance parameters and the knot of the structure. For the plating brittleness of the steel parts, the law between the electrical conductivity and the plating can become the basis for non-destructive testing. 1 test principle Factors that affect the conductivity of the material changes a lot, but are related to and controlled by the organizational structure. Due to changes in the structure of the material, resulting in changes in free electron motion and affect the conductivity changes. The impact factors are as follows: 1.1 Temperature Affect the material temperature, lattice movement increased, the material resistance increases, so seasonal changes, the test temperature changes will cause changes in conductivity. However, in the actual test, the instrument, test block and the workpiece in the same test