基于CSP流程的30CrMo钢热处理工艺研究

发布时间：2018-03-19 02:32

  本文选题：CSP工艺　切入点：奥氏体晶粒　出处：《武汉科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：合金结构钢30CrMo因其具有良好的力学性能而在石油化工、机械制造、刀具模具等工业领域得到了广泛的应用。已有研究表明,与传统热连轧工艺相比,采用CSP工艺生产的30CrMo带钢在表面脱碳、成分偏析、组织性能稳定性等方面具有明显的优势。然而,对于30CrMo钢而言,其最终的使用性能往往取决于热处理工艺。基于此,本文以CSP工艺生产的30CrMo热轧带钢为研究对象,系统研究了其在不同热处理工艺条件下组织和性能的变化规律,为其热处理工艺的制定提供了理论依据。对CSP热轧30CrMo带钢淬火工艺的研究表明:试验钢初始组织由细小均匀的珠光体和铁素体组成。在再加热过程中,初始组织奥氏体化,且随着淬火温度的升高以及保温时间的延长,奥氏体晶粒不断长大,其奥氏体长大动力学模型为D=392189.3exp(-1.02×105/RT)t0.031;经水淬或油淬后均得到马氏体组织,但不同工艺条件下马氏体的类型、尺寸和力学性能不同。当淬火温度较低且保温时间较短时,基体中的马氏体组织主要由板条马氏体和片状马氏体组成。随着淬火温度的升高以及保温时间的延长,片状马氏体的含量逐渐减少,板条马氏体的含量不断增加,尺寸增大,强度和硬度值下降。不同加热工艺下经油淬后的屈服强度可表示为:σs=-4050.4+16272.2d-1/2;对CSP热轧30CrMo带钢在淬火保温阶段脱碳行为的研究表明:脱碳层厚度随淬火温度的升高和保温时间的延长逐渐增大,但是在1000-1200℃时脱碳层厚度先减小后增大,并建立了脱碳层厚度变化的数学模型;对CSP热轧30CrMo带钢回火工艺的研究表明:随着回火温度升高和时间延长,马氏体回复加剧,亚结构粗化,450℃时界面开始有渗碳体析出,强度值和硬度值逐渐降低,断后伸长率增大,在5h出现二次硬化现象;综上所述,对于本文中所研究的CSP热轧30CrMo带钢而言,其最佳的热处理工艺为淬火温度860-900℃、保温15 min、油淬后在400-500℃的范围内回火5h。
[Abstract]:Alloy structural steel 30CrMo has been widely used in petrochemical, mechanical manufacturing, tool mould and other industries because of its good mechanical properties. The 30CrMo strip steel produced by CSP process has obvious advantages in surface decarburization, composition segregation, microstructure and mechanical stability, etc. However, for 30CrMo steel, the ultimate performance often depends on the heat treatment process. In this paper, the microstructure and properties of 30CrMo hot rolled strip produced by CSP process were studied systematically under different heat treatment conditions. The study on quenching process of CSP hot rolled 30CrMo strip shows that the initial microstructure of the test steel is composed of fine and uniform pearlite and ferrite, and the initial microstructure is austenitizing during reheating. With the increase of quenching temperature and the prolongation of holding time, the austenite grain grows continuously. The austenite growth kinetic model is DX 392189.3exp-1.02 脳 10 5 / RTT 0.031. The martensite structure is obtained by water quenching or oil quenching, but the martensite type is obtained under different technological conditions. When the quenching temperature is low and the holding time is short, the martensite structure in the matrix is mainly composed of lath martensite and lamellar martensite. With the increase of quenching temperature and the prolongation of holding time, the microstructure of martensite in matrix is mainly composed of lath martensite and sheet martensite. The content of lamellar martensite decreases gradually, the content of lath martensite increases and the size increases. The strength and hardness value decreased. The yield strength of oil quenched under different heating process can be expressed as: 蟽 -4050.4 16272.2d-1 / 2. The decarburization behavior of CSP hot-rolled 30CrMo strip during quenching and heat preservation is studied. The results show that the decarburization layer thickness increases with the increase of quenching temperature and preservation. The prolongation of temperature time gradually increased, However, at 1000-1200 鈩，

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