Inspection of Casting and Forging
Release time:
2023-01-03 17:09
Source:
Inspection of Casting and Forging
Poor ultrasonic penetration of castings and forgings, coarse grains, uneven organization and other complex information system management interfaces, all enhance the scattering of an ultrasonic wave, and the energy can be effectively attenuated, so that the detectable thickness is smaller than that of forgings.
There are many interference clutter in castings and forgings. When the sound wave is scattered at the interface of uneven tissue and rough particles, the scattering signal intensity is large and is detected and received. The reflection noise of rough casting surface and the messy forest echo (also called grass echo) appearing on the range screen may drown the defect echo and hinder the identification of defect echo.
The surface coupling condition of casting and forging is poor, the rough surface of casting and forging is not conducive to acoustic coupling, the surface hardness is high, and grinding is difficult.
It is difficult to quantify the defects of castings and forgings, because the acoustic attenuation of castings and forgings is large, the defect shape is complex, and the error of quantitative analysis and evaluation of control defects based on artificial defect problems is large, so it is difficult to quantify the defects by calculation method.
The above is the difficulty of casting and forging detection. But on the other hand, due to the low quality requirements of castings, large size, many individual defects, and strong regularity of casting defects, casting inspection still has a certain value.
China's small and medium-sized castings and forgings, especially precision investment casting, have small size, light weight and small processing capacity. On the fixed magnetic particle inspection device, it can be magnetized at least in the following two directions, roughly divided into vertical directions. A good method can use such a DC or pulsating DC working current, with wet treatment enterprise continuous method inspection. It can be directly used by electrification method, rod wearing method, magnetic flux method and different coil methods of enterprises.
For large and heavy castings and forgings, the local part or diaphragm is magnetized in at least two generally perpendicular directions. Good can use a DC or half-wave rectifier portable or mobile magnetic particle detector, using direct contact method or magnetic yoke method, dry continuous method or wet continuous method, local or split method casting technology detection. The test shall normally be carried out in two mutually perpendicular directions.
In order to prevent the casting in contact with the electrode from burning out, it is suggested that the following solutions can be taken: when the contact is not completely in contact with the casting surface, do not switch on the current, and when the current is cut off, please remove the contact. and have sufficient cleanliness and proper contact. The yoke method is preferred for machining smooth surfaces. Due to the influence of casting stress, some cracks (cold cracks) will delay the initiation of cracks, so they should not be detected immediately after casting, but should be detected 1-2 days after casting. If the casting defects exceed the acceptance work criteria and are rejected, but allow digging (shovel) welding repair welding, repair welding area development should also pay attention to the internal control system to delay the generation of cracks. The inspection shall be carried out with naked eyes. When inspecting the quality and safety levels of 001 and 01, they can only be used for less than 3 times.
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Defects in castings and forgings
The defects produced in the casting and forging process are similar to the defects produced in the ingot, but they are still process defects, including pores, inclusions, shrinkage holes, loose holes, cracks, etc.
Production of castings and forgings
Castings and forgings must be melted by electric furnaces, mainly electric arc furnaces and induction furnaces. According to the different lining materials and slag system, can be divided into acidic furnace and alkaline furnace. Carbon steel and low alloy steel can be smelted in any furnace, but high alloy steel can only be smelted in alkaline furnaces.
Inspection of Casting and Forging
The complex information system management interface of casting and forging, such as poor ultrasonic penetration, coarse grain, uneven organization, etc., all enhance the scattering of an ultrasonic wave by students, and the energy can be effectively attenuated, so that the detectable thickness is smaller than that of forgings.
What are the advantages and disadvantages of casting and forging
One of the advantages of casting and forging is the flexibility of design. Personnel design has a large degree of freedom of design choice for the shape and size of castings, especially for parts with complex shapes and hollow sections. Steel castings can be manufactured using a unique process known as core assembly.
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