Common problems and preventive measures of the hot

Common problems and preventive measures of stainless steel surface treatment

common problems and preventive measures of stainless steel surface treatment

I. common problems in stainless steel surface treatment and product processing:

1. Weld defects: weld defects are relatively serious, and manual and mechanical grinding methods are used to make up for them. The grinding marks produced cause uneven surface and affect the appearance

2. Surface inconsistency: only pickling and passivation of welds will also cause uneven surface and affect the appearance

3. Scratches are difficult to remove: the overall pickling and passivation can not remove all kinds of scratches generated in the processing process, and can not remove carbon steel, splash and other impurities adhered to the stainless steel surface due to scratches and welding spatter, resulting in chemical corrosion or electrochemical corrosion and rust in the presence of corrosive media

4. Uneven grinding, polishing and passivation: pickling and passivation treatment is carried out after manual grinding and polishing. For workpieces with large area, it is difficult to achieve uniform treatment effect, and the ideal uniform surface cannot be obtained. And the labor cost and auxiliary material cost are also high

5. Limited pickling capacity: pickling passivation paste is not omnipotent. It is difficult to remove the black oxide scale produced by plasma cutting and flame cutting

6. The scratches caused by factors are relatively serious: in the process of hoisting, transportation and structural processing, the scratches caused by collision, dragging, hammering and other factors are relatively serious, which makes the surface treatment more difficult, and is also the main reason for rust after treatment

7. Equipment factors: during the bending and bending of profiles and plates, scratches and creases are also the main reasons for corrosion after treatment

8. Other factors: during the procurement and storage of stainless steel raw materials, the bumps and scratches caused by hoisting and transportation are also relatively serious, which is also one of the reasons for corrosion

II. Preventive measures:

1. Storage, hoisting, transportation

1) storage of stainless steel parts: there should be a special storage rack, which should be a wooden or painted carbon steel support or padded with a rubber pad to isolate it from carbon steel and other metal materials. Do not put it in fog during storage. The storage location should be convenient for lifting and relatively isolated from the storage area of other materials. Protective measures should be taken to avoid the pollution of dust, oil and rust on stainless steel

2) hoisting of stainless steel parts: when hoisting, special lifting appliances, such as lifting belts, special collets, etc., shall be used. It is strictly forbidden to use steel wire ropes to avoid scratching the surface; And when lifting and placing, avoid scratching caused by impact and collision

3) transportation of stainless steel parts: during transportation, transportation tools (such as trolley, battery car, etc.) should be used, and isolation and protection measures should be taken to prevent dust, oil and rust from polluting stainless steel. Dragging is strictly prohibited to avoid bumping and scratching

2, processing

1) processing area: the processing area of stainless steel parts should be relatively fixed. Isolation measures shall be taken for the platform in the stainless steel parts processing area, such as laying rubber pads. The fixed location management and civilized production of stainless steel parts processing area should be strengthened to avoid damage and pollution to stainless steel parts

2) blanking: the blanking of stainless steel parts adopts cutting, plasma cutting, sawing, etc

⑴ shearing: during shearing, it should be isolated from the feeding support, and the hopper should also be paved with rubber pads to avoid scratching

⑵ isochronous with Weston? 705 compared with polyethylene resin containing traditional solid antioxidant, cutting slag should be cleaned up after plasma cutting. During batch cutting, the completed parts shall be cleaned out of the site in time to avoid the contamination of the workpiece by the cutting slag

⑶ sawing and blanking: when sawing and blanking, the clamping shall be protected by rubber, and the oil stain and residue on the workpiece shall be cleaned after sawing

3) machining: stainless steel parts should also be protected during machining such as turning and milling, and the oil stain, iron filings and other sundries on the surface of the workpiece should be cleaned up after the completion of the operation

4) forming processing: in the process of plate rolling and bending, effective measures should be taken to avoid causing scratches and creases on the surface of stainless steel parts

5) rivet welding: when assembling stainless steel parts, it is necessary to avoid forced assembly, especially flame calibration assembly. If plasma cutting is used temporarily in the assembly or manufacturing process, isolation measures shall be taken to avoid the pollution of cutting slag to other stainless steel parts. After cutting, the cutting slag on the workpiece should be cleaned

6) welding: before welding stainless steel parts, oil dirt, rust, dust and other sundries must be carefully removed. Argon arc welding shall be adopted as far as possible during welding, and small current and fast welding shall be adopted during manual arc welding to avoid swinging. It is strictly forbidden to strike an arc in the non welding area. The ground wire is properly positioned and firmly connected to avoid arc scratch. Anti spatter measures (such as whitewashing) shall be taken during welding. After welding, the slag and splash shall be thoroughly cleaned with a stainless steel (carbon steel is not allowed) flat shovel

7) multi layer welding: during multi-layer welding, the slag between layers must be removed. During multi-layer welding, the temperature between layers shall be controlled, which generally shall not exceed 60 ℃

8) weld: the weld joint shall be ground, and the weld surface shall be free of slag, pores, undercuts, splashes, cracks, incomplete fusion, incomplete penetration and other defects. The weld and the base metal shall transition smoothly and shall not be lower than the base metal

9) orthopedic: for the orthopedic of stainless steel parts, flame heating method should be avoided, especially repeated heating of the same area is not allowed. When orthopedic, try to use mechanical devices, or use wood hammer (rubber hammer) or rubber pad to hammer. It is forbidden to hammer with iron hammer to avoid damaging stainless steel parts

10) handling: when handling stainless steel parts during processing, transportation tools (such as trolley, battery car or crown block, etc.) should be used, and isolation and protection measures should be taken to prevent dust, oil and rust from polluting stainless steel. It is strictly forbidden to drag directly on the platform or the ground, and it is strictly forbidden to bump and scratch

3, surface treatment

1) cleaning and grinding: if there is damage, it should be polished, especially the scratch and splash caused by contact with carbon steel parts, and the damage caused by slag cutting must be carefully and thoroughly cleaned and polished

2) mechanical polishing: appropriate polishing tools shall be used for polishing, and the treatment shall be uniform, and over polishing and re scratching shall be avoided

3) oil and dust removal: before pickling and passivation of stainless steel parts, oil dirt, oxide skin, dust and other sundries must be removed according to the process

4) water blasting treatment: different micro glass beads and different process parameters should be selected according to different treatment requirements, and overspray should be avoided

5) pickling and passivation: pickling and passivation of stainless steel parts must be carried out in strict accordance with the process requirements

6) cleaning and drying: after pickling and passivation, neutralization, washing and drying should be carried out strictly according to the process, and the residual acid should be completely removed

7) protection: after being familiar with the technical indicators, use methods, operation specifications and other steel parts of the equipment, protection should be done to avoid personnel touching and secondary pollution of oil, dust and other debris

8) avoid reprocessing: after the surface treatment of stainless steel parts, BASF should avoid reprocessing the parts or products