摘要
本文主要研究50CrV钢中产生低温二次硬化现象的热处理工艺并通过实验分析第二相的形成特点说明微合金钢中产生低温二次硬化的前提条件和相应曲线的表现形式。
采用适当的热处理工艺,测绘不同回火温度下50CrV、9CrV、50Cr、GCr15等钢的回火硬度曲线后认为:对不同的钢种而言,低温二次硬化的低温是相对而言的,50CrV钢的相对最佳回火温度约在180~190℃左右。
为解释9CrV、50CrV钢中的低温二次硬化现象,通过对比实验和不同回火时间处试样的显微分析,本文认为第二相的沉淀析出、马氏体的回火分解、残余奥氏体的马氏体转变共同决定了微合金钢的最终硬化情况。特别是由于微合金元素的存在,促进了回火过程中第二相的弥散析出。如果工艺满足笫二相的沉淀强化大于回火中马氏体分解引起的软化效应,就会在硬度曲线中产生明显的二次硬化峰。最后,根据Orowan机制,选择Asbby—Orowan关系式对沉淀强化所产生的屈服强度增量σ_(PR)进行估算,与马氏体分解引起的强度降低比较,所得结果与实验测绘曲线大体相符。
由此得出结论:在一定的热处理工艺条件下,通过微合金化产生的弥散强化,可以弥补马氏体分解引起的硬度降低,从而使材料获得优良的综合力学性能即同时提高了材料的韧性和硬度。
The heat treatment technique which can result in secondary hardening phenomenon at low temperature tempering of 50CrV steel has been studied. And a series of experiments were designed to analyse the fonnation character of second phase particles which was formed during the temperring. From all of this analyses, we can obtain the necessary factors which may result in secondary hardening at low temperature and we also enumerated all kinds of curve shape that maybe exist.
From the graphs which we mensurated through special heat treatment technique, we can draw conclusions that to different materials 'the low temperature' is reletive, and the optimal temperature is at 180~ 190 C for 50CrV steel which the secondary hardening can be observed.
In order to explain the secondary hardening at low temperature which exists in the SOCrV, 9CrV steel .We designed the comparative experiment and observed the microstructure of the sample which has occurred the secondary hardening. The last experiment results were determined by three factors : the second phase precipitation, die decompound of martensite, martensitic transformation of remnant austenite. Especially, the microalloyed elements, which were made the second phase precipitation equally. There would be found distinct second hardening apex in the curve when .
In a brief, dirogh a special heat treatment technique die strcngdiening by precipition of microalloyed carbide can compensate die falling of hardening, so the optimal mechanical property of the steel was acquired .
引文
[1] 谢建新.低合金钢的现状和发展趋势.金属世界,1998,No.5:3~4.
[2] Serosh Engieer, Mohammad Mujahid: Processing and properties of Low Carbon Steel Instute. Matallurgical Society, AIME, 1991,vol.243, p.2305-2308.
[3] T.Gladman and F.B.Pickering: Journal Iron and Steel institute, 1997,vol. 205, p.653.
[4] W.Barr:The Fracture of Metals,Institution of Metallurgists, 1998,p.239.
[5] 叶治文.低合金高强度钢开发与研究的新进展.鞍钢技术,2000,(7).
[6] 杨景明等.美国对微合金钢的研究及应用.国外金属加工,1989,(2).
[7] 赵量.非调质钢的发展和第三代非调质钢.钢铁钒钛,1990,2(11).
[8] E.R.Morgan et al.:Journal of Metals, August 1989,p856.
[9] 徐国庆.中碳微合金非调质钢的发展.钢铁钒钛,1987,7(1),P87.
[10] 崔文暄等.微合金化中碳非调质钢的韧性.钢铁钒钛,1990,2(1),P14.
[11] 李桂芬等.我国非调质钢的发展与应用[J].钢铁研究学报,1994,6(1):93-97.
[12] W.E.Duckworth and J.D.Baird:Journal of Iron and Steel Institute, 1995,vol.207,p.643.
[13] 何才.微合金化中碳非调质钢的组织性能与V的作用研究(北科大硕士论文),1989.
[14] 方卫平.V-Ti-N钢中微合金化元素的相互作用(北科大硕士论文),1986.
[13] 赵建平.中碳非调质钢中珠光体的形态对性能的影响(北科大硕士论文),1988.
[15] J.L.Mihelich et al.:Journal of Iron and Steel Institute, 1991,vol.209,p.435.
[16] W.E.Duckworth:Journal of Iron and Steel Institute, 1993,vol. 163,p223.
[17] 蒋克等.微合金钒钢中碳氮化物在铁素体中脱溶曲线的研究,钢铁钒钛,1989,10(3):63-67.
[18] A.P.Coldren,R.L.Cryderman and Y.E.Smith:processing and properties of Low Carbon Steels,AIME,1997,p145.
[19] A.Brownrigg and G.G.Brown:Journal of the Autealian Institute of Metals,1993,vol.17,p1996,vol.11,p.109.
[20] T.Terazawa et al.:Towards Improved Ductility and Toughnee, Climax Molybdenum Company Conferencd,Kyoto, 1998,p.101.
[21] J.Jirani and G.Tither:Ibid.,p.135.
[22] Lubuska A.Z.等.低碳钢复合微合金弥散强化的研究.国外钢铁钒钛,1989(3),P78-82. .
[23] Andrzej Lis 等.高强度钒微合金化钢轧制后碳化膜的形成.国外钢铁钒钛,1990(3),P23-29.
[24] Serosh Engineer 等.微合金化中碳钢的研制与应用述评.国外钢铁钒钛,1988(3),P51-57.
[25] N.J.Petch:proceedings,Swampscott Conference, 1994,MIT Press,p.43.
[26] 雍歧龙等.微合金钢-物理和力学冶金.机械出版社,1989.293.
[27] G.A.Beiser:American Society of Metals Preprint no 138,1999.
[28] K.J.Irvine and F.B.Pickering:Ibid.,1996,vol.178,p232.
[29] 曹萌之等.中国含钒低、微合金化钢的开发与前景.钢铁钒钛,2000(3),P1-11.
[30] 雍歧龙.微合金钢中微合金碳氮化物在奥氏体中的沉淀问题(钢铁研究总院博士论文),1987.
[31] 马翔等.钛钒微合金钢中碳氮化物的鉴定与分析.钢铁钒钛,1989(1),P89-93
[32] A.M.Sage.结构钢中的钒.国外钢铁钒钛,1994,6(5),P1-7.
[33] Korchynsky M. Pitfalls of Substitution[J]. Stratcor Eagle, 1998, 6-7.
[34] Holschun L T.31st IISI Annuel Report[J]. Stahl and Eisen, 1997,11.
[35] A.J.McEvily and C.L.Magce:The Iron and Steel Institute,publication no .114,1995,p.111.
[36] Roberts, W., in HSLA83.M.Korchynsky, ed., ASM. Ohio, 1994,33.
[37] R.Phillips and J.A.Chapman:Journal of Iron and Steel Institue, 1992,vol.204,p.615.
[38] 戚正风.热处理原理,北京:冶金工业出版社,1986.
[39] 雍歧龙等.微合金钢-物理和力学冶金.机械出版社,1989.471.
[40] R.W.K.Honeycombe,JISI,1973,No8,21.
[41] 雍歧龙等.微合金钢-物理和力学冶金.机械出版社,1989.466.
[42] 李碧容.微合金碳氮化合物在铁素体中沉淀问题的研究(昆明理工大学硕士论文),2000.
[43] 王笑天.金属材料学.机械工业出版社,1993,33.
[44] Serosh Engieer, Mohammad Mujahid: Processing and properties of Low Carbon Steel Instute. Matallurgical Society, AIME, 1991,vol.243, p.2305-2308..
[45] T. Gladman and F.B.Pickering: Journal Iron and Steel institute, 1987,vol. 205, p.653.
[46] 雍歧龙.微合金碳氮化物在铁素体中的沉淀强化机制的理论分析.科学通报,1989,(9):707~709.
[47] W. Barr:The Fracture of Metals,Institution of Metallurgists,1998,p.239.
[48] 雍歧龙等.固溶度积公式、理想化学配比值与微合金钢化学成分的设计,钢铁,1988,No.1.