In today’s automotive industry almost all car and truck radiators, oil coolers and air conditioning heat exchangers are manufactured using Nocolok Controlled Atmosphere Brazing (CAB). One of the most critical element...In today’s automotive industry almost all car and truck radiators, oil coolers and air conditioning heat exchangers are manufactured using Nocolok Controlled Atmosphere Brazing (CAB). One of the most critical elements of the brazing process is the atmosphere used to protect the flux. Oxygen content is the major variable affecting the performance of the nitrogen atmosphere. Furnace design and flow rate are the major factors affecting oxygen content. Optimisation of these atmosphere parameters has a significant impact on operating cost, and on the quality and consistency of the brazed product. Computational fluid dynamics provides a tool to visualise the atmosphere conditions within the furnace and to explore the effects of changing some of the variables. Modelling the atmosphere in a typical CAB furnace has shown the importance of the integrity of the curtains in maintaining the low oxygen levels required for successful Nocolok brazing. For a given set of curtains it has shown that the only effective way of decreasing oxygen levels is to increase atmosphere gas flow.展开更多
The effects of gas composition, temperature, ore to coke ratio and prereduction rate of ore on coke degradation were studied. The results showed that 1% increment in solution loss of coke reduces coke strength by 0.6%...The effects of gas composition, temperature, ore to coke ratio and prereduction rate of ore on coke degradation were studied. The results showed that 1% increment in solution loss of coke reduces coke strength by 0.6%, and the coke degradation is accelerated with the temperature. The higher the temperature, the more coke surface is involved in reactions, and the less negative effect on coke strength is. Hydrogen exerts stronger effect on coke degradation than CO at high temperature. The coke degradation is decreased with the reduction of ore to coke ratio and increase of ore prereduction rate.展开更多
Cold-rolled high strength steel sheets for automobiles contain more Mn and Si based alloy elements, which, under the reducing atmosphere in the annealing furnace, will get enriched on the strip surface. Since the furn...Cold-rolled high strength steel sheets for automobiles contain more Mn and Si based alloy elements, which, under the reducing atmosphere in the annealing furnace, will get enriched on the strip surface. Since the furnace rollers and the strips contact frequently, alloy elements on the roller surface will form hard protuberance. We call this protuberance ＂pick-up＂. In addition, with the increase of the amount of dust in the furnace atmosphere, the occurrence of furnace roller pick-up will also increase. Through chemical reaction and physical accumulation analysis combined with practical experience, the causes of pick-up in different furnace sections were analyzed. Methods of preventing furnace roller pick-up in the high strength steel sheet processing line were discussed and solutions to improving the strip surface quality in the continous annealing furnace were provided.展开更多
A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability ...A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.展开更多
This study aimed to analyze the mechanical properties of the compound FeCuC when compacted at varying pressures and sintered in two different types of furnaces. Besides the different models of furnace, the working atm...This study aimed to analyze the mechanical properties of the compound FeCuC when compacted at varying pressures and sintered in two different types of furnaces. Besides the different models of furnace, the working atmospheres were varied： one is being composed with argon gas and another constituted with a balancing nitrogen and hydrogen. Atmospheres vary with the amount of production and the type of equipment used. The compound generated is used in the manufacture of rings for mechanical seals and is currently manufactured by the sintering process in passing furnace. The sintering was performed in a static furnace with argon atmosphere and compared with the same compound sintered in passage furnace with hydrogen and nitrogen atmosphere. The analysis of the properties of the tested material was performed with the aid of metallography using a scanning electron microscope, which verified the particle size distribution, chemical elements and pores present. Brinell hardness and Vickers micro hardness tests were also used to analyze the properties of this material after completion of the two processes. Thus, the research carried out has shown that variations may occur in the mechanical properties when processed in different furnace types and different sintering atmospheres.展开更多
文摘In today’s automotive industry almost all car and truck radiators, oil coolers and air conditioning heat exchangers are manufactured using Nocolok Controlled Atmosphere Brazing (CAB). One of the most critical elements of the brazing process is the atmosphere used to protect the flux. Oxygen content is the major variable affecting the performance of the nitrogen atmosphere. Furnace design and flow rate are the major factors affecting oxygen content. Optimisation of these atmosphere parameters has a significant impact on operating cost, and on the quality and consistency of the brazed product. Computational fluid dynamics provides a tool to visualise the atmosphere conditions within the furnace and to explore the effects of changing some of the variables. Modelling the atmosphere in a typical CAB furnace has shown the importance of the integrity of the curtains in maintaining the low oxygen levels required for successful Nocolok brazing. For a given set of curtains it has shown that the only effective way of decreasing oxygen levels is to increase atmosphere gas flow.
文摘The effects of gas composition, temperature, ore to coke ratio and prereduction rate of ore on coke degradation were studied. The results showed that 1% increment in solution loss of coke reduces coke strength by 0.6%, and the coke degradation is accelerated with the temperature. The higher the temperature, the more coke surface is involved in reactions, and the less negative effect on coke strength is. Hydrogen exerts stronger effect on coke degradation than CO at high temperature. The coke degradation is decreased with the reduction of ore to coke ratio and increase of ore prereduction rate.
文摘Cold-rolled high strength steel sheets for automobiles contain more Mn and Si based alloy elements, which, under the reducing atmosphere in the annealing furnace, will get enriched on the strip surface. Since the furnace rollers and the strips contact frequently, alloy elements on the roller surface will form hard protuberance. We call this protuberance ＂pick-up＂. In addition, with the increase of the amount of dust in the furnace atmosphere, the occurrence of furnace roller pick-up will also increase. Through chemical reaction and physical accumulation analysis combined with practical experience, the causes of pick-up in different furnace sections were analyzed. Methods of preventing furnace roller pick-up in the high strength steel sheet processing line were discussed and solutions to improving the strip surface quality in the continous annealing furnace were provided.
文摘A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.
文摘This study aimed to analyze the mechanical properties of the compound FeCuC when compacted at varying pressures and sintered in two different types of furnaces. Besides the different models of furnace, the working atmospheres were varied： one is being composed with argon gas and another constituted with a balancing nitrogen and hydrogen. Atmospheres vary with the amount of production and the type of equipment used. The compound generated is used in the manufacture of rings for mechanical seals and is currently manufactured by the sintering process in passing furnace. The sintering was performed in a static furnace with argon atmosphere and compared with the same compound sintered in passage furnace with hydrogen and nitrogen atmosphere. The analysis of the properties of the tested material was performed with the aid of metallography using a scanning electron microscope, which verified the particle size distribution, chemical elements and pores present. Brinell hardness and Vickers micro hardness tests were also used to analyze the properties of this material after completion of the two processes. Thus, the research carried out has shown that variations may occur in the mechanical properties when processed in different furnace types and different sintering atmospheres.
