The Development of Surfacing Technology in China and Its Application in Basic Industry

1. Application of surfacing technology in China's basic industry

Surfacing technology in China's nearly 50 years of development process for the rise and development of basic industries has made important contributions to its application throughout the mechanical energy transportation and metallurgical industries and other fields are only the iron and steel industry in the field of various types of energy field of the valve traffic The locomotive and the car engine friction parts as an example to describe the application of surfacing technology.

3.1 roll surfacing

Roller is the key equipment for rolling mill production Roller quality directly affect the rolling mill's working efficiency Rolling product quality and production Roll consumption, etc. According to statistics, a rolling mill in China to produce hot rolled steel per ton of steel consumption 1.46 kg roll equivalent to 25 yuan cold Steel consumption roll 1.24 kg roll equivalent to 35 yuan China's annual output of steel has more than 0.1 Gt annual consumption of about 3 billion yuan of the roll so the use of surfacing method to repair the old roll to improve the service life of the roll has become China's steel enterprises to reduce costs to improve the efficiency of the important Initiatives are also in line with China's energy-saving materials, the basic national policy of clean production in the 1990s, the vast majority of large and medium-sized iron and steel enterprises have the ability to repair roll and repair and energy-saving enterprises laid the technical foundation has also made significant economic benefits The main reason for the early scrapping of the roll is that wear and surface cracks such as cracks caused by alternating hot and cold environments due to extrusion wear and abrasive wear due to extrusion, etc. Roll roll not only needs to restore the size of the roll and roll neck more important Is to improve the roll of cold and hot fatigue and wear resistance The main reason for the early scrapping of the rollers is wear and surface cracks such as cracks caused by hot and cold alternating environments due to extrusion wear and abrasive wear due to extrusion. Roll roll welding is not only necessary to restore the size of the roll and roll neck. Improve the cold resistance of the roll body fatigue and wear resistance.

 

Low alloy high strength steel type wire is the most commonly used grade 30CrMnSi surfacing layer hardness 35 40 HRC because of the low hardness and therefore can only be used to restore the size 3Cr2W8V is commonly used hot die steel steel wire after stress relief annealing layer hardness Up to 40 50 HRC Mainly used for the first mill Rolling mill The forging roll of the pipe mill can increase the roll life by 13 times Cr13 2Cr13 3Cr13 is a martensitic stainless steel type for the surfacing repair roll and the steel roll for the steel roll Surfacing layer hardness of 45 50 HRC and high alloy high-carbon tool steel wire of the typical grades are 80Cr4Mo and 8W2VMnSi for finishing mill forged steel work roll and cold and hot rolling mill support roll surfacing repair surfacing layer hardness up to 50 60 HRC due to the high alloying elements and high carbon content prone to surfacing cracks in this need to be higher preheat and interlayer temperature.

Flux 260 431 430 is China's roll welding repair commonly used alkaline melting flux because of its low oxidation can reduce the welding of carbon chromium in the welding process in the welding process, but this flux is not easy to slag surfacing surface quality The use of sintered flux in the roll surfacing increases the quality of these fluxes at 500 ° C for easy automatic slagging and the improvement in the transition coefficient of the alloying elements such as carbon chromium vanadium in the wire. The design performance of the surfacing layer.With the welding wire submerged arc welding technology even if the multi-wire submerged arc surfacing welding efficiency is limited and the wire soldering of the single-channel width of the small frequent overlap to significantly reduce the surfacing layer The use of metal so that with a very high-stack welding technology, especially in the roll repair technology in the roll repair shows a good application prospects such as with a very welding technology in Baosteel Phase II project has introduced four large slab caster The repair of the guide roller has been applied to the welding material with 1Cr13NiMo specifications for 0.4 mm × 30 mm and 0.4 mm × 50 mm surfacing efficiency and quality of the traditional method significantly improved. Silk with ingredients easy to adjust the characteristics of the stability of the arc is particularly suitable for the production of high hardness rolling difficult to surfacing alloy materials so in recent years flux cored wire surfacing technology development and application of the industry has attached great importance to the development of domestic units of the cold Roller and Hot Roller Continuous Casting Roller Continuous Casting Roller Stacking Flux Series Welding Wire and Using CMoWMnSiV Flux Cored Wire with 107 Flux Successfully Surfacing Repairing Hot Rolling Billet Roller The relevant units in China have made positive aspects in the intelligent aspects of roll surfacing equipment Efforts to develop a roll stacking intelligent control system can be used with different welding power supply and the corresponding wire feeding mechanism to achieve CO 2 MIG MAG and submerged arc welding is particularly suitable for special-shaped cross-section workpiece surfacing.

 

3.2 valve surfacing

The life and reliability of the valve depends primarily on the quality of the sealing surface. The sealing surface is not only subject to abrasion and impact due to the periodic opening and closing of the valve but also by high temperature corrosion oxidation due to the working environment and medium And so on the role of China's petrochemical enterprises due to sealing surface failure caused by the waste of the valve caused by the waste is very serious Therefore, according to the valve in which the work environment requires a reasonable surfacing method to repair or strengthen the valve sealing surface to have excellent anti- Anti-erosion, high temperature and other comprehensive performance can effectively extend the service life of the valve to reduce costs.

Research valve sealing surface surfacing technology in China began in the early 1960s after 40 years of development from the main valve welding method non-automated welding method inefficient manual arc welding and oxyacetylene flame surfacing development widely used and efficient automated welding methods such as TIG welding electrode submerged arc welding, tungsten plasma arc powder welding and laser welding and the welding material and the welding wire also uses a lot of welding electrodes in the welding powder based steering We have developed a martensitic alloy systems austenitic iron-based alloy welding nickel-based alloys, and cobalt-based hardfacing welding alloy Cr13 series martensitic electrode for a pressure lower than 16MPa temperature below 450? carbon steel containing valve high crack resistance difference between the amount of carbon required 2Cr13 surfacing selecting appropriate metal welding process before and after heat treatment CrMn austenitic welding wire weld metal without preheating the superior performance of Cr13 alloy austenitic CrNi ? type commonly used in the electrode working temperature of less than 600 or less steam valve surfacing welding F1 ×× series NiCrBSi powder NDG - type 2 NiCrWSi welding powder F2 ×× series of cobalt-based hardfacing F3 ×× series end and an iron-based powder surfacing temperature corrosion valve surfacing both temperature and pressure valves have been widely used.

Valve seal surface thickness of the welding layer is the valve designers are very concerned about the important parameters from the surfacing point of view if the thickness is too small, the dilution of the welding metal to improve the thickness of the excess is not only a waste of precious materials and many welding alloys will be due to stress Increase the crack and therefore the thickness of the stacking layer of the control standard is not in the surfacing metal is not diluted under the premise of the base metal to choose the minimum thickness of the country in the thickness of the sealing surface of the valve have developed a corresponding standard China has GB984 - 85 and EJ / T1027.9 - 96 Reasonable control of the dilution of the base metal on the sealing surface of the sealing surface is an important guarantee for obtaining the high quality sealing surface. When the dilution rate of the surfacing alloy system is constant, the dilution rate is the surfacing method and the surfacing process parameters. Single layer dilution rate from small to large order of various surfacing method sorting oxyacetylene flame plasma arc tungsten argon arc welding manual arc surfacing submerged arc surfacing arc welding Although the dilution rate is too large but the surfacing efficiency is The highest single-layer heap in a variety of valve surfacing methods up to 3 5 mm tungsten argon arc single layer stacking dilution rate can be controlled at 10% 20% but heap height is too small To be welded 2 3 layer can reach 3 mm effective heap for the valve surfacing plasma arc surfacing technology there are two kinds of powder plasma arc surfacing single layer effective pile up to 2 mm dilution rate 5% Wire plasma arc single layer stacking dilution rate can be controlled at 5% 15% but generally need to surfacing more than 2 layers can guarantee more than 3mm effective pile height.

China's surfacing technology experts in the valve sealing surface surfacing materials and surfacing methods have made a positive effort but the surfacing material development space is still very large, such as the development of the valve sealing surface surfacing sintered flux submerged arc welding wire alloy steel electrode Nickel-based alloy welding rods and other high both the high cost of surfacing and low welding dilution of the surfacing technology needs to be developed surfacing equipment automation and intelligent level also need to improve.

 

3.3 surfacing of key components of the engine

In the high temperature corrosion and frequent impact conditions of the various types of engine into the exhaust valve is often due to the destruction of the cone surface of the early failure of the use of reasonable surfacing methods and welding materials repair engine valve disc cone can effectively extend the service of the valve Life of foreign diesel locomotive diesel engine valve plate with iron-based austenitic heat-resistant steel to create its pan cone surfacing Stellite high temperature wear-resistant alloy or valve plate using high-temperature nickel-based alloy and the cone surface is no longer surfacing reinforcement China 's Oriental Red series of 175 - type 180 series of wind - series 240 - type 280 diesel engine exhaust valve are used 4Cr14NiW2Mo or 21 - 12N - type austenitic heat - resistant steel plate surface are required to surfacing Stellite - 6 cobalt - based High temperature alloys such as a domestic locomotive plant using oxyacetylene flame surfacing valve plate cone practice shows that the 4Cr14NiW2Mo made by the valve in terms of welding dilution rate of about 10% and 21 - 12N base metal manufacturing exhaust valve Of the welding dilution rate of about 7% of the hardness of the surfacing layer are up to 40 HRC above the production of 180,000 pieces of welding by the locomotive running test does not appear The taper surface cracks crack perforation peeling off the destruction of the phenomenon of a plant to solve the engine valve cone cone due to high temperature corrosion damage to the status quo using tungsten argon arc welding method in the GH4033 cone surface surface welding nickel-based Hastelloy reasonable control reactor Welding dilution rate can make the valve anti-high temperature corrosion performance has been significantly improved.

 

Pistons are one of the most important parts of the engine. The piston ring groove, especially the first ring groove, is subjected to a high pressure of 6 14 MPa and a high temperature wear of 220? 280? As the engine is moving towards high life and high power Aluminum alloy piston ring groove welding reinforcement has become an important measure to improve engine performance and extend the life of the piston ring groove welding method is mainly argon arc welding and plasma arc surfacing and welding alloy selection is to improve the aluminum alloy Hardness and heat resistance for the principle of commonly used alloy elements Ni Fe and rare earth element Fe can improve the thermal strength of aluminum alloy but adding too much to cause cracking Ni can improve the strength and heat resistance of aluminum alloy such as welding wire Ni The content of more than 10% can increase the piston life of 3 times the addition of rare earth elements can be aluminum alloy needle eutectic refinement and spheroidization and with AlCu Mn and other high melting point compounds to improve the aluminum alloy piston ring groove high temperature strength and Heat resistance, but the amount should be controlled at about 1.

The repair of the camshaft and the tappet friction pair in the engine also shows a good application prospect. The tread material of the automobile engine is made of 40Cr to improve its abrasion resistance. Generally, the brazing steel composite structure is used but the ceramic The brittleness is easy to cause the ceramic pieces to be broken or peeled. The surfacing method is used to create a layer of ceramic-reinforced metal matrix composites on the surface of the tappet steel shaft. It is expected to solve the problem of the abrasion resistance of the tappets and the camshaft Can also use surfacing wear-resistant alloy method to improve its wear resistance.

 

2. Conclusion

Surfacing technology in China after 50 years of development of its application throughout the field of basic industries in China in the field of surfacing research theory and foreign industrial developed countries is not inferior to the development of surfacing materials, surfacing equipment, automation and intelligence The level of precision and efficient surfacing technology development and application of computer technology and simulation technology in the surfacing technology in the application of the level of a certain gap with foreign research and development of high quality and low efficiency and flexible cleaning advanced surfacing technology and its widely used in Advanced manufacturing industry is the historical mission of our welding colleagues.