The quality of alloy steel castings is including appearancequality, internal quality and use quality. Appearance quality refers to theroughness of casting surface, surface defects, size deviation, shape deviationsand weight bias. The internal quality of alloy steel casting parts mainlyrefers to the chemical composition, physical properties, mechanical properties,microstructure and holes of the alloy steel casting parts, the crack, inclusion,segregation, etc.. Use quality of alloy steel castings refersto the durable capacity of casting work under different conditions, includingwear, corrosion resistance, thermal shock of cold shock, fatigue,shock-absorbing and process performance such as cutting, welding, etc.
The qualities of alloy steel castings have a great impact on the performanceof mechanical products. For example, wear resistance and dimensional stabilityof alloy steel castings affect directly on the maintain life of precisionmachine tools; different sizes of kinds of pump impeller, housing and thehydraulic pressure cavity, profile accuracy and surface roughness of alloy steelcastings directly affects the efficiency of the pump and the hydraulic system,energy consumption and cavitations' development; the strength and resistance tocold shock of internal combustion engine cylinder block, cylinder head, cylinderliner, piston rings, exhaust pipes, directly affect the engine's workinglife.
In investment casting, it is necessary to control and check the quality ofalloy steel castings. First, formulate the process control andtechnical requirements from the raw materials, auxiliary materials to eachspecific alloy steel casting. Control and inspection each process strictlyaccording to the technical rules and technical conditions. Finally, inspect thequality of finished alloy steel castings matched with detecting methods and toreasonable and appropriate testing persons. The general checking is toappearance of the quality of alloy steel castings and it can be used todetermine the comparison specimens’ surface roughness of alloy steel casting;while surface cracks can be subtle coloring method, magnetic particle inspectionmethod. Use the audio, ultrasonic, eddy current, X-ray and γ-ray and othermethods to check and judge the internal quality of the alloy steel castings.