What are the main inspection methods for forgings?

The main inspection methods of Dalian forgings include chemical composition analysis, mechanical property test, low magnification inspection, metallographic high magnification inspection and nondestructive testing.

Chemical composition analysis. The general chemical composition analysis is mainly the content of carbon, manganese, silicon, sulfur and alloy elements. Forgings are sampled from the equivalent riser end. Important parts need to be sampled from water and riser end in order to understand the degree of segregation. For special parts or defects, it is often necessary to analyze the content of gas, inclusions and trace impurity elements for quality confirmation or research.

Mechanical property test. The mechanical property tests commonly used by forging factories are hardness, drawing, impact and bending tests. From the performance data, we can find the existing problems of the material. Bubbles, porosity, cracks, grain size and tempering brittleness in the steel can often be reflected on the fracture of the mechanical property sample.

Low magnification test. Sulfur printing, pickling and fracture are commonly used low magnification inspection items. Sulfur print can show the distribution of sulfur on the section; Pickling can show various macro defects such as component segregation, porosity, shrinkage cavity, subcutaneous bubbles, inclusions, peeling, white spot cracks and so on; The fracture inspection can find the defects that can not be revealed by sulfur printing and pickling. It is a simple and applicable method.

Metallographic high-power test. This method is widely used in micro inspection and also in studying the micro characteristics of macro defects. It is to observe the prepared metallographic sample with an optical microscope under the magnification of 50 to 2000 times, and check the inclusions, metal microstructure and grain size.

NDT. Magnetic particle, fluorescence, coloring, ray, eddy current, ultrasonic and other methods are usually used. Correctly selecting the flaw detection method to comprehensively and carefully inspect the surface and internal defects of forgings can accurately judge the size, quantity and distribution of defects. In the quality inspection of forgings, nondestructive testing has become one of the most important methods.