ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
1. The present situation of steel structure engineering in construction in recent 20 years, due to the strong support of the state and the strong demand of the market, the steel structure in China has developed rapidly. The "sunrise industry" steel structure enterprises called the construction industry have emerged as the times require, but the professional and technical personnel are relatively scarce, and the quality control level of the project is low, which leads to the emergence of some steel structure projects. The serious unreasonable phenomena of technology and economy have even caused many engineering quality accidents. The importance of nondestructive testing methods for heavy losses 2. The safety and reliability of building steel structures originate from design, while their own quality originates from raw materials, processing, fabrication and field installation. Generally, there are three ways to evaluate the safety and reliability of building steel panels: (1) simulation experiments; (2) destructive experiments; (3) non-destructive testing simulation experiments simulate the specifications, materials and structural forms of building steel structures in a fixed proportion to simulate the safety and reliability of building steel structures in their working conditions. The simulation experiment can quantitatively evaluate the overall performance of the building steel structure, but its cost is highly recalculated.
The destructive test diaphragm uses the destructive method to test and inspect the performance index of the sample. Destructive experiments have the advantages of intuitive testing results, less error and controversy, but destructive experiments are only suitable for sampling, not for all the workpieces, so we can not get a complete conclusion. Non-destructive testing can detect 100% of raw materials and workpieces, and welding with relatively low economic cost, as the main connection mode of building steel structure, plays a decisive role in the quality of the whole project. Domestic experts on steel structure summarized the failure modes of steel structure engineering in Wenchuan earthquake in 2008 as follows: beam-column weld connection failure in frame joint area 3) column foot weld failure and anchor bolt failure. From the above reasons, it can be seen that the key quantities to control the quality of weld can be divided into appearance defects, weld size, surface defects and near surface defects. Surface defect and internal defect. Among them, appearance defect and weld size are mainly inspected by measuring tools and visual inspection, while surface defect, near surface defect and inner weasel defect are inspected mainly by non-destructive testing. NDT (Non-destructive_ve esting abbreviated as NDT) is to develop and apply various technical methods so as not to damage the tested object. To test, locate, measure and evaluate defects, evaluate completeness, performance and composition, and measure geometric characteristics in a functional and functional manner, and to test, inspect and test materials and parts.
According to different physical principles, there are many kinds of non-destructive testing methods. Permeability testing (PT), magnetic particle testing (MT), radiographic testing (RT) and ultrasonic testing are widely used in steel structure engineering. Radiographic testing and ultrasonic testing are mainly used to detect internal sound defects. Magnetic particle testing is mainly used to detect surface and near surface defects. Permeability testing can only be used for surface opening defects. Principle, scope of application, advantages and disadvantages of loss detection method 4.1 Liquid Penetrant Testing (PT) is a non-destructive detection method based on capillary phenomenon to reveal surface opening defects of non-porous solid materials. For short, penetration detection seeps the permeate into the surface opening defect of the workpiece by the action of a thin tube, removes the superfluous permeate on the surface with a removal agent, sprays the imaging agent on the surface of_, and by capillary action, the permeate in the defect is adsorbed and shows the basic steps of penetration detection on the surface: pretreatment, infiltration, removal, and so on. Drying, imaging and post-processing penetration detection and coloring penetration detection.
Penetration testing is suitable for surface cracks, cockroaches, cold isolation, looseness and other defects. It is widely used for ferromagnetic and non-ferromagnetic forgings, castings, welds, machined parts, powder metallurgical parts, ceramics, plastics and glazed products. In the construction of steel structure engineering, it is mainly used for the detection and penetration of surface opening defects of forgings, castings, welding parts and austenitic stainless steel, which is relatively simple in use and control. The equipment used for penetration detection can be a simple combination of containers containing osmotic fluid, remover and imaging agent respectively. It can also be a complex computer-controlled automatic processing system. The main advantages of penetration detection are: intuitive display; simple operation; high sensitivity of penetration detection, and detection of cracks with openings as small as 1 micron. The main limitations of penetration testing are: it can only detect surface opening defects; rough surface and pore will produce additional background, which will interfere with the identification of testing results; and it will pollute parts and environment.