On the quality inspection method of the hottest fo

Methods of forging quality inspection (Part 1)

in today's era, people have higher requirements for the use of products, and correspondingly higher requirements for forgings for manufacturing products. The manifestations of forging quality problems are numerous and miscellaneous. Some types of forging defects will seriously reduce the performance of forgings, threaten the safety and reliability of use, and shorten the service life. The consequences of the existence of such defects are serious. Therefore, the quality inspection of forgings also puts forward higher requirements, that is, forgings with defects must not be left behind, especially those with defects that seriously affect the service performance. To achieve this, in the inspection and control of forging quality, in addition to fully using conventional inspection methods and means, the 100 meter high residence) should also adopt faster and more accurate inspection methods and methods that reflect the contemporary level, so that its evaluation of forging quality, judgment of forging defect nature, judgment of cause and analysis of formation mechanism are more accurate and more realistic, so as to ensure that defective forgings are not missed, And can take appropriate measures to improve and improve the quality of forgings

as mentioned above, the inspection of forging quality is divided into appearance quality inspection and internal quality inspection. Generally speaking, the inspection of appearance quality belongs to non-destructive inspection, which is usually carried out with the naked eye or low magnification, and nondestructive testing method is also used when necessary. As for the inspection of internal quality, due to the requirements of its inspection content, some must adopt destructive inspection. With the development of sensor technology, it is commonly referred to as anatomical test, such as low magnification inspection, fracture inspection, high magnification structure inspection, chemical composition analysis and mechanical property test, and some can also adopt nondestructive testing methods. In order to evaluate the quality of forgings more accurately, Destructive testing methods and nondestructive testing methods should be used together. In order to analyze the quality problems of forgings from a deep level, the research work of machine rationality should also be assisted by transmission or scanning electron microscope, electron probe, etc

generally, the inspection methods for the internal quality of forgings can be summarized as follows: macrostructure inspection, microstructure inspection, mechanical property inspection, chemical composition analysis and nondestructive testing

macrostructure inspection is an inspection to observe and analyze the macrostructure characteristics of forging by visual inspection or low magnification (generally below 30). The commonly used methods for the macro structure inspection of forgings are low magnification corrosion method (including hot corrosion method, cold corrosion method and electrolytic corrosion method), fracture test method and sulfur printing method

low power corrosion method is used to inspect the cracks, folds, shrinkage cavities, pore segregation, white spots, porosity, non-metallic inclusions, segregation and agglomeration, distribution form of streamline, grain size and distribution of forgings of structural steel, stainless steel, superalloy, aluminum and aluminum alloy, magnesium and magnesium alloy, copper alloy, titanium alloy and other materials. However, for different materials, the etchant and etching specification are different when showing macrostructure

the fracture test method is used to check the defects such as white spots, laminations and internal cracks of structural steel and stainless steel (except austenite), the graphite carbon of spring steel forgings and the overheating and Overburning of the above steel types. For aluminum, magnesium, copper and other alloys, it is used to check whether the grains are fine and uniform, whether there are oxide films, oxide inclusions, the former is expensive and other defects

the sulfur printing method is mainly applied to large forgings of some structural steels to check whether the sulfur distribution is uniform and the sulfur content

except that the test pieces of structural steel and stainless steel forgings used for low magnification inspection are not subject to final heat treatment, forgings of other materials are generally subject to final heat treatment before low magnification inspection

fracture samples are generally subject to the specified heat treatment

the principle of microstructure inspection is to use optical microscope to inspect the microstructure of forgings of various material grades. The inspection items generally include the essential grain size, or the grain size at the specified temperature, that is, the actual grain size, non-metallic inclusions, microstructure such as decarburization layer, eutectic carbide non-uniformity, overheating, overburning structure and other required microstructure