电场频率对45钢交流电场增强粉末法渗硼的影响
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摘要
在800℃粉末法渗硼过程中对中碳45钢试样和渗剂施加交流电场,研究电场频率对粉末法渗硼的影响规律和作用机制。对渗硼保温过程中试样的温度、渗硼层显微组织、相结构、厚度及显微硬度分布等进行观测分析。结果表明:交流电场使试样温度高于渗硼保温炉温,电场电流恒定时,随频率从20Hz增至400Hz,试样温升先降低后升高,硼化物层及增碳区厚度均先减小后增加;当电场电流为3A时,硼化物层为单相Fe2B;当电场电流≤2A时,随频率增加,硼化物层由FeB+Fe2B双相变为单相Fe2B,渗层表层硬度降低、硬度分布曲线趋于平缓。分析认为,电场频率通过综合影响渗剂反应、活性硼原子及含硼活性基团在试样表面的吸附和试样内原子的扩散来影响渗硼。
An alternating current field(ACF) was applied to samples and media during pack boriding on medium carbon 45 steel at 800 ℃. The effects and working mechanism of the A.C frequency on the boriding were studied. The temperature of the samples during the soaking of the boriding, boriding cases' microstructure, phases, thickness and micro-hardness distribution were investigated. The results show that the ACF makes the temperature of the boriding sample higher than that of the furnace during soaking. With the increase of the frequency from 20 Hz to 400 Hz, the temperature rise first decreases and then increases. The thickness of the boride zone and the carbon-enriched zone first decreases and then increases. When the ACF current is 3 A, the single phase Fe2 B is obtained. When the ACF current is not more than 2 A, with the increase of the ACF frequency, the boride zone changes from the dual phases FeB + Fe2 B to the single phase Fe2 B. The hardness of the surface layer decreases. The slope of the hardness profile along the boriding case becomes flat. It is proposed that the ACF frequency affects the pack boriding through affecting reactions among the boriding agent, adsorptions of active boron atoms and boroncontaining species on the samples' surface, and diffusion in the treated samples.
An alternating current field(ACF) was applied to samples and media during pack boriding on medium carbon 45 steel at 800 ℃. The effects and working mechanism of the A.C frequency on the boriding were studied. The temperature of the samples during the soaking of the boriding, boriding cases' microstructure, phases, thickness and micro-hardness distribution were investigated. The results show that the ACF makes the temperature of the boriding sample higher than that of the furnace during soaking. With the increase of the frequency from 20 Hz to 400 Hz, the temperature rise first decreases and then increases. The thickness of the boride zone and the carbon-enriched zone first decreases and then increases. When the ACF current is 3 A, the single phase Fe2 B is obtained. When the ACF current is not more than 2 A, with the increase of the ACF frequency, the boride zone changes from the dual phases FeB + Fe2 B to the single phase Fe2 B. The hardness of the surface layer decreases. The slope of the hardness profile along the boriding case becomes flat. It is proposed that the ACF frequency affects the pack boriding through affecting reactions among the boriding agent, adsorptions of active boron atoms and boroncontaining species on the samples' surface, and diffusion in the treated samples.
引文
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[15]程健,谢飞,孙力,等.交流电场增强45钢中低温粉末法渗硼特性[J].金属学报,2014,50(11):1311-1318.CHENG J,XIE F,SUN L,et al.Characterization of alternating current field enhanced pack boriding for 45 carbon steel at low and medium temperatures[J].Acta Metallurgica Sinica,2014,50(11):1311-1318(in Chinese).
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[2]HUNGER H J,TRUTE G.Boronizing to produce wear-resistant surface layer[J].Heat Treat Met,1994(2):31-39.
[3]彭志辉,杨志兵,王少武,等.稀土对45钢渗硼层组织和性能的影响[J].金属热处理,2004,29(7):31-34.PENG Z H,YANG Z B,WANG S W,et al.Effect of rare earth on structure and properties of boronizing layer[J].Heat Treatment of Metals,2004,29(7):31-34(in Chinese).
[4]HUANG Z R,LI P N,XIE F,et al.Effect of rare elements on powder boro-carbo-nitriding at low temperature[J].Journal of Rare Earths,2000,18(3):205-209.
[5]ANTHYMIDIS K G,STERGIOUDIS G,TSIPAS D N.Boride coatings on non-ferrous materials in a fluidized bed reactor and their properties[J].Science&Technology of Advanced Materials,2002,3(4):303-311.
[6]BARTSCH K,LEONHARDT A.Formation of iron boride layers on steel by d.c.-plasma boriding and deposition process[J].Surface&Coatings Technology,1999,116(99):386-390.
[7]章桥新,叶卫平,张建红,等.微波场下渗硼介质的温度特性研究[J].热加工工艺,2007,36(20):53-55.ZHANG Q X,YE W P,ZANG J H,et al.Study temperature property of boriding medium under microwave field[J].HotWorking Technology,2007,36(20):53-55(in Chinese).
[8]YANG H P,WU X C,YANG Z,et al.Enhanced boronizing kinetics of alloy steel assisted by surface mechanical attrition treatment[J].Journal of Alloys&Compounds,2014,590(5):388-395.
[9]孙希泰,徐英,孙毅.21世纪化学热处理将由其他能助扩渗代替纯热扩渗[J].金属热处理,2003,21(8):27-29.SUN X T,XU Y,SUN Y.Thermo-chemical treatment with pure heat diffusion penetration will be replaced by other types of energy aided diffusion penetration in the 21st century[J].Heat Treatment of Metals,2003,21(8):27-29(in Chinese).
[10]XIE F,ZHU Q H,LU J J.Influence of direct current field on powder-pack boriding[J].Solid State Phenom,2006,118:167-172.
[11]XIE F,SUN L,PAN J W.Characteristics and mechanisms of accelerating pack boriding by direct current field at low and moderate temperatures[J].Surface&Coatings Technology,2012,206(11-12):2839-2844.
[12]ANGKURARACH L,JUIJERM P.Effects of direct current field on powder-packed boriding process on martensitic stainless steel AISI 420[J].Archives of Metallurgy&Materials,2012,57(3):799-804.
[13]XIE F,SUN L,CHENG J.Alternating current field assisted pack boriding to Fe2B coating[J].Surface Engineering,2013,29(3):240-243.
[14]XIE F,CHENG J.Study on effects of alternating current field to pack boriding of medium carbon steel[J].International Heat Treatment&Surface Engineering,2014,8(3):111-116.
[15]程健,谢飞,孙力,等.交流电场增强45钢中低温粉末法渗硼特性[J].金属学报,2014,50(11):1311-1318.CHENG J,XIE F,SUN L,et al.Characterization of alternating current field enhanced pack boriding for 45 carbon steel at low and medium temperatures[J].Acta Metallurgica Sinica,2014,50(11):1311-1318(in Chinese).
[16]武汉材料保护研究所,上海材料研究所.钢铁化学热处理金相图谱[M].北京:机械工业出版社,1980:52-54.Wuhan Materials'Protection Research Institute,Shanhai Materials Research Institute.Metallograph of thermo-chemical treated iron and steel[M].Beijing:Mechanical Industry Press,1980:52-54(in Chinese).
[17]DEARNLEY P A,BELL T.Engineering the surface with boron based materials[J].Surface Engineering,1985,1(3):203-217.