Discussion on magnetic powder flaw detection of press impeller Li Baozhong1, Wang Peichun1, Cheng Shi2 Baogang Group Technology Center, Baotou 014010 Baosteel Group Steelmaking Plant, Inner Mongolia Baotou 014010, the location and direction of the defect, to find the defects for practical applications Good reference meaning. 1 Introduction In industrial production, the reliability of equipment operation is a very important performance indicator. In order to make the equipment operate normally, it is necessary to carry out strict quality inspection on the equipment. Magnetic particle inspection is a routine non-destructive testing technology, because it can not only ensure the safe operation of the equipment, save raw materials, but also has simple equipment, easy to carry and easy to operate. The detection of fast display is intuitive, easy to judge, high sensitivity and good repeatability, and has been widely used in industrial production. 2The principle of flaw detection After the ferromagnetic material and the workpiece are magnetized, due to the discontinuity, the magnetic field lines on the surface of the workpiece and the near surface are locally deformed to generate a leakage magnetic field, and the magnetic powder applied on the surface of the workpiece is adsorbed to form a proper illumination. The visible magnetic marks are visible underneath, thereby showing the position, shape and size of the discontinuity. As shown in Figure 1. The original defect of the wheel is easily formed by the type 1 butt welding. The structure of the rib is relatively complicated and the volume is small, which is easy to produce incomplete penetration. When the pores or internal cracks in the raw material fail to be welded during the forging but are crushed and enlarged, delamination is formed in the sheet. It is an area-type discontinuous defect, which is potentially dangerous. When the layer is extended or interrupted at the edge of the web blade, the magnetic particle inspection can be effectively verified. If the layer is located inside the specimen, the magnetic particle inspection will be carried out. Can not be effectively detected. The characteristics of such defects are fixed lengths, and the damage is also greater under certain action conditions. To 2 running defective leaf surface is prone to fatigue cracking. Its characteristics are to go to the rule, the mark is clear, and there is a certain depth. The position of the drawing is due to the decrease of the strength of the heat-affected zone in the welding, so that the impeller of high-speed operation is prone to fatigue cracks in this part, and their characteristics are clear and have a certain depth. 4 Selection of flaw detection process The main work process includes six steps of pretreatment, magnetization, magnetic powder application, magnetic trace analysis, demagnetization and heat treatment. 4.2 The choice of the instrument According to the existing fillet weld magnetic particle flaw detector model is èµ€1, the magnetic spacing is 18 out of the "11, is a kind of active joint, single magnetic conversion of the magnetic particle flaw detector has the advantage that the minimum magnetic spacing is small, And according to the field detection conditions, the magnetic joints can be best passed through the joints. The magnetic pole spacing is 1 and the lifting force is greater than or equal to 4. 5 heart 3, it fully meets the requirements of the flaw detection equipment in the 164 is 0-94 standard. The detection of the equipment by the flaw detector fully meets the inspection requirements of the impeller. 4.3 Selection of flaw detection methods Because different types of workpiece defects are different, there are delamination, pull marks, non-metallic inclusions, and shrinkage holes in the raw materials. White spots, pores, cold partitions, etc., in welding, forging, casting, heat treatment, mechanical plus king, in-service equipment, cracks, pores, inclusions, incomplete penetration, un-bonding, folding and other defects, so the magnetization method The choice is very important. The surface magnetization method includes an energization method, a middle pole method, a conductor method, a magnetic enthalpy method, and a cross magnetic boring method. The alternating magnetic field magnetized wet magnetic powder continuous method is selected according to the structure and shape of the workpiece to perform the magnetic particle flaw detection on the impeller. 4.4 Purpose of inspection The impeller welding and the edge of the foliar are detected to produce original defects and fatigue cracks. 4.5 Selection of inspecting personnel and testing equipment Only those who have obtained the Class 1 magnetic particle inspection data certificate after technical training can operate and obtain the oral magnetic powder inspection qualification certificate before they can fill in and issue the inspection report, and bear corresponding technical responsibilities. The inspector's corrected visual acuity shall not be less than 1. and shall not be color blind. The color is weak. The Al-30/100 sensitivity test piece is required to meet the sensitivity requirements of the laboratory and on-site inspection. 4.6 Position of the probe in actual operation In order to ensure that the original defect and the fatigue crack can be effectively detected, the direction of the magnetic field generated by the two contacts of the magnetic particle flaw detector and the extending direction of the possible defect must be perpendicular, in order to better detect the actual The defect is often detected by the cross-magnetic method, that is, the surface of the same 4.7 inspection surface is exposed to the surface of the inspection surface to expose the metal luster. 4.8 Process The magnetic particle inspection process shall be arranged after each process that is prone to defects. For materials that have a tendency to produce delayed cracks, they should be arranged in two places after welding. The 49 magnetization specification must comply with the 473091 magnetic particle inspection equipment. Provisions of 63721. When the electromagnetic pole spacing is 20011, the alternating electromagnetic vehicle should have at least 441 lifting force. The black magnetic powder should have high magnetic permeability and low residual magnetic properties, and the magnetic powders should not attract each other. When the continuous method is used for energization, the magnetic powder or magnetic suspension must be applied within the energization time. The energization time is at least 138 in the same part of the magnetization time, and the magnetization can be stopped after the magnetic suspension is stopped for at least 13. In the simulated field conditions of the laboratory, the sensitivity requirements meet the requirements of the A1-30/100 level. The demagnetization device should be able to ensure that the surface magnetic field strength of the workpiece after demagnetization is less than 1 ancestral chamber 4.10 Sensitivity test Under the requirement of ensuring the lifting force of the flaw detection equipment, and the magnetic suspension reaches the specified concentration, the sensitivity is correctly determined within the determined magnetization range. The test piece is attached to the weakest magnetic field to make the cross groove and the circular groove on the sensitivity test piece clear to meet the sensitivity of the field. The standard test piece should be attached to the crack-prone figure 23 and the magnetic field strength is the most. The weaker places also require that the cross-shaped and circular grooves on the sensitivity test piece are clearly visible. Meet the requirements of the melon 4730-94 standard. 5 On-site inspection 5.1 Field conditions and the condition of the inspected workpiece The temperature must be such that the magnetic suspension has good fluidized illumination not lower than the built-in OLX, and ensures that the magnetic trace is clearly distinguished. There must be no iron attraction on the impeller surface. There are factors that are unfavorable for the detection of defects such as oxide scales and speech objects in the oil field. If the color of the surface and the color of the magnetic suspension are difficult to distinguish, a contrast agent can be used to improve the resolution and it is not easy to cause missed detection. Due to the long operating period of the impeller and the lack of surface condition, we have adopted a contrast enhancement gauge to get a good effect. Operation, judgment. After the record, it is judged that it is not a pseudo-defect in the test, and it should be recorded according to the standard of 16473094. The magnetic powder test is qualified for the first level. 6 The results of the flaw detection After magnetic particle inspection on 6 pairs of impellers, it is found that there are 3 surface cracks in 3 impellers. Under 1 shake, all the elimination after grinding ensures that the equipment can operate normally. 7 Conclusions It is proved that it is completely feasible to use the single-magnetic corner fillet magnetic particle flaw detector to check whether the equipment generates fatigue crack after using the single-magnetic corner weld magnetic particle flaw detector. It can detect the defects on the surface or near surface of the ferromagnetic material very well. , to provide a guarantee for the normal operation of the equipment. [The Ministry of the Ministry of Non-destructive Inspection Intelligence Network. NDT. Beijing; Beijing News Development Bureau, 21.31 æ±¾ [[National Boiler and Pressure Vessel Non-destructive Testing Qualification Appraisal Committee. Domain powder flaw detection [North East China Boiler and Pressure Vessel Safety Magazine News 6 burnt account 37 swollen mouth phlegm and numbness 3 A mouthful of male fox in 01401 2 buckle Single Roller Corn Thresher,Hand Crank Corn Sheller,Antique Corn Sheller,Electric Corn Sheller Hunan Xinta Machinery Manufacturing Co., Ltd. , http://www.xyagriculture.com