合金元素对铸造冷作模具钢的固态相转变温度及其动力学的影响

发布时间：2018-03-23 04:22

本文选题：铸造冷作模具钢　切入点：合金元素　出处：《吉林大学》2017年博士论文　论文类型：学位论文

【摘要】：冷作模具钢是模具中极其重要的一类,在工业生产中占据着举足轻重的地位,这要求其具有高硬度、高强度、高韧性和高耐磨性等基本性能。热处理作为冷作模具钢获得这些基本性能最主要的途径,合理的热处理工艺可以充分发挥出冷作模具钢的性能潜力,提高模具的质量和使用寿命,从而提高经济效益。通常情况下,热处理加热工艺是以铁碳平衡相图为依据,但是铁碳平衡相图为二元平衡态相图,对于多元合金钢而言,在实际生产过程中却存在一定的局限性,只能对加热温度做估算。因此,寻找一种新的方法,确立成分和温度之间的对应关系,对指导合金钢的热处理工艺的加热温度的确定具有很重要的意义。本文研究了合金元素(Cr、Mn、Mo和V)对Fe-M-C三元合金钢的奥氏体化相转变起始温度和动力学的影响,建立了合金元素(Cr、Mn、Mo和V)与起始温度之间的相关关系,得到了成分与起始温度之间的回归方程。同时,以YBD-3和SDC99两种铸造合金模具钢作为实验对象,对回归方程的实用性进行了验证。本文主要研究结果如下:(1)Fe-M-C三元合金钢(M=Cr、Mn、Mo和V)从珠光体向奥氏体的相转变过程可以用位置饱和形核,扩散控制生长和碰撞修正三个过程来描述。其相转变过程受到原始组织、合金含量和过热度的影响。其中,原始组织越细密,其可以提供更多形核位置的同时,还可以缩短元素的有效扩散距离;合金含量越多,其对碳元素的限制就越明显,其形成的碳化物在奥氏体的长大过程中会起到钉扎作用;过热度越大,相转变驱动力越大,越有利于奥氏体相的形成和长大。(2)Fe-M-C三元合金钢(M=Cr、Mn、Mo和V)发生奥氏体化相转变的起始温度与合金元素(Cr、Mn、Mo和V)之间存在线性关系。其中,除了Mn元素以外,起始温度都随着Cr、Mo和V元素含量的增加而升高,具体的一元线性回归方程如下:a.Fe-Cr-C三元合金钢:(K)=1037.427+6.420×铬元素含量(wt.%)b.Fe-Mn-C三元合金钢:(K)=1016.823-6.593×锰元素含量(wt.%)c.Fe-Mo-C三元合金钢:(K)=1009.918+11.233×钼元素含量(wt.%)d.Fe-V-C三元合金钢:(K)=1023.706+3.707×钒元素含量(wt.%)(3)通过对多元铸造合金钢的成分与发生奥氏体化相转变的起始温度之间进行多元回归分析,结果表明起始温度与合金元素(Cr、Mn、Mo和V)的含量之间基本呈线性关系,可以满足已知合金钢成分,通过回归方程对发生奥氏体化相转变的起始温度进行预测的要求,其具体的回归方程为:(K)=1017.960+8.606×铬元素含量(wt.%)-6.863×锰元素含量(wt.%)+5.304×钼元素含量(wt.%)+12.892×钒元素含量(wt.%)(4)以YBD-3和SDC99两种铸造合金模具钢作为实验对象,对合金元素(Cr、Mn、Mo和V)的含量与奥氏体化相转变的起始温度之间的多元回归方程的实用性进行验证分析。结果显示:当YBD-3和SDC99两种铸造合金模具钢采用以回归方程计算出的起始温度的预测值作为依据而设计的热处理方案二进行热处理时,两种铸造合金模具钢都会得到更为精细、碳化物尺寸更小、分布更均匀的组织。并且,其回火态的硬度明显好于方案一(根据起始温度的实验测量值而设计的热处理方案)。此外,性能检测结果显示,YBD-3和SDC99两种铸造合金模具钢经过热处理方案二处理后,其抗拉强度和冲击韧性明显高于方案一。总之,本文研究了合金元素(Cr、Mn、Mo和V)对奥氏体化相转变的起始温度和动力学的影响,建立了合金元素含量与起始温度之间的回归方程,并通过实验对比验证了回归方程的实用性。实现了已知合金元素含量,通过回归方程就可以对奥氏体化相转变的起始温度进行预测,并以此作为依据制定热处理工艺参数的目的。
[Abstract]:Cold die steel is a kind of important mold, plays an important role in industrial production, which requires that it has high hardness, high strength, high toughness and high performance wear resistance. Heat treatment as cold die steel for these basic properties of the main path, reasonable heat treatment process can give full play to the performance potential of cold die steel, and improve the service life of the mold quality, so as to improve the economic benefit. Usually, heat treatment process is based on the iron carbon equilibrium diagram as the basis, but the iron carbon equilibrium phase diagram for two yuan equilibrium phase diagram for multicomponent alloy steel, but there are limitations some in the actual production process, can only be estimated on the heating temperature. Therefore, to find a new method to establish the corresponding relationship between composition and temperature, the heating temperature of the heat treatment process of alloy steel guide It is important in this paper. The effects of alloying elements (Cr, Mn, Mo and V) on the effect of austenitizing Fe-M-C three yuan alloy steel phase transformation start temperature and dynamics, established the alloy elements (Cr, Mn, Mo and V) and the relationship between the onset temperature, the regression equation between the components and the initial temperature. At the same time, YBD-3 and SDC99 two kinds of casting alloy die steel as experimental object, the practicability of the regression equation was verified. The main results of this paper are as follows: (1) Fe-M-C three alloy steel (M=Cr, Mn, Mo and V) can be used to position saturated nucleation from pearl to the process of phase transformation of austenite, diffusion controlled growth and avoidance three process to describe the phase transition process. By the original organization, content and effect of alloy superheat. Among them, the original organization more fine, which can provide more nucleation position at the same time, can also shorten the yuan The effective diffusion distance; alloy content is more, the limitations of carbon is more obvious, the formation of the carbide will play a role in the growth process of pinning austenite; superheat increasing, phase transformation driving force is bigger, more conducive to the formation and growth of austenite phase. (2) Fe-M-C three alloy steel (M=Cr, Mn, Mo and V) occurred starting temperature and alloying elements of austenite phase transformation (Cr, Mn, Mo and V). There is a linear relationship between them, in addition to the Mn element, the initial temperature with the increase of Mo and Cr, V content increased, a linear concrete the regression equation is as follows: a.Fe-Cr-C three alloy steel: (K) =1037.427+6.420 * chromium content (wt.%) b.Fe-Mn-C three alloy steel: (K) =1016.823-6.593 * Mn (wt.%) c.Fe-Mo-C three alloy steel: (K) =1009.918+11.233 * d.Fe-V-C (wt.%) content of molybdenum alloy steel (K: three yuan =1023.706+3.707 * V) The content of elements (wt.%) (3) through multiple regression analysis between the starting temperature of multi cast alloy steel composition and austenite phase transformation. The results show that the initial temperature and the alloy elements (Cr, Mn, Mo and V) showed a linear relationship between the basic content, can satisfy the known composition of steel alloy, forecast the regression equation of initial temperature on phase transition of the austenite of the requirements, the regression equation is: =1017.960+8.606 (K) * chromium content (wt.%) -6.863 * Mn (wt.%) +5.304 * molybdenum (wt.%) * +12.892 vanadium element content (wt.%) (4) to YBD-3 SDC99 and two kinds of casting alloy die steel as the experimental object, the alloy elements (Cr, Mn, Mo and V) to verify the practicability analysis of multiple regression equations between the initial temperature and the content of austenite phase transformation. The results showed that when YBD-3 and SDC99 two kinds of casting alloy Prediction of mold steel by initial temperature by regression equation to calculate the value of heat treatment plan and design as the basis for the two heat treatment, two kinds of casting alloy die steel will be more fine, the carbide size smaller, more uniform distribution of the organization. The tempering hardness and significantly better than the scheme (heat treatment scheme designed according to the experimental values of the initial temperature). In addition, the performance test results showed that YBD-3 and SDC99 two kinds of casting alloy die steel with heat treatment scheme of two after treatment, the tensile strength and impact toughness was significantly higher than that in solution. In short, this paper studies the alloy elements (Cr, Mn, Mo and V) influence on the initial temperature and the kinetics of austenite phase transformation, the regression equation was established between alloy elements and initial temperature, and the utility of the regression equation is verified by experiments. The known alloy The initial temperature of austenite transformation can be predicted by regression equation, and the purpose of making heat treatment process parameters is based on this equation.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG142.45;TG161

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