常州亿创钣金加工厂专业从事精密钣金加工、激光切割加工为主的钣金加工型厂家

常州亿创钣金加工厂

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厂家解读热处理变形应用钣金加工工艺

2018-05-13 17:06:28 常州亿创钣金加工厂 阅读

钣金加工主要是对各种金属材料的处理,在不同的材料当中,所进行的加工处理也是不同的,所以需要使用不同的加工技术。其中热处理变形是钣金加工生产中一项重要工艺,热处理变形有两种类型:一是尺寸的变化,二是零件几何形状的变化。热处理技术不同,零件尺寸和几何形状的变形及防变形方法亦不相同。
Sheet metal processing is mainly the treatment of various metal materials, in the different materials, the processing is also different, so the need to use different processing technology. The deformation of heat treatment is an important process in the process of sheet metal processing. There are two types of heat treatment deformation: one is the change of size and the two is the change of the geometric shape of the part. Different methods of heat treatment, deformation and deformation prevention of parts size and geometry are also different.

 热处理加热奥氏体化过程中,保温时间越长,温度越高,则溶入奥氏体的碳越多,马氏体转变时产生的膨胀越大。冷却时,马氏体膨胀最大,上贝氏体次之,下贝氏体和屈氏体的体积变化很小。低温回火时,马氏体发生收缩,收缩量与过饱和的碳含量成正比。在室温-200℃加热时,部分残余奥氏体会转变成马氏体,出现膨胀。但该膨胀因200℃附近马氏体发生分解,因此表现上变化不大。在常规热处理中,零件形状变化的主要原因是热处理加热和淬火时发生的热应力和相变应力。加热速度过快、相对于加热炉而言零件太大、零件各部分的温度不同,都会导致热变形。保温时,加工的残余应力会发生释放而产生变形,零件的自重也会导致变形。冷却时,由于零件不同部位的冷却速度不同,会形成热应力而使零件变形。即使冷却速度相同,冷却总是表面快,心部慢。因此,先相变的表面使未相变的心部发生塑性变形。如果材料中存在合金成分的偏析,或者表面脱碳,则相变应力更不均匀,更易导致零件变形。另外,如果零件厚薄不均,也会造成冷却速度不同。
In the process of heat treatment austenitizing, the longer the holding time is, the higher the temperature is, the more carbon is dissolved into austenite, and the larger the expansion is during martensitic transformation. When cooling, martensite expands the largest, followed by the upper bainite, and the volume of the lower bainite and the body is very small. At low temperature tempering, martensite shrinks and the amount of shrinkage is directly proportional to the supersaturated carbon content. When heated at room temperature of -200, part of austenite is transformed into martensite and expanded. However, the expansion of the martensite due to decomposition near 200 c has little change.  In conventional heat treatment, the main reason for the change of the shape of the parts is the thermal stress and phase transformation stress during heat treatment and quenching. The heating rate is too fast, the parts are too large and the temperature of each part of the parts is different, which will lead to thermal deformation. During thermal insulation, the residual stress will be released and the deformation will be caused. When cooling, due to different parts of the cooling rate of different parts, will form thermal stress and deformation of parts. Even if the cooling speed is the same, the cooling surface is always fast and the heart is slow. Therefore, the surface of phase transformation causes plastic deformation of the core without phase transformation. If there is segregation of alloy components or decarburization, the stress of phase transformation will be more uneven and more likely to cause deformation of parts. In addition, if the thickness of the parts is uneven, the cooling rate will also be different.

  在锻件的热处理中,减少变形的零件摆放方式,一是尽可能垂直吊挂,二是垂直放在炉底部,三是用两点水平支撑,支点位置处于全长的三分之一与四分之一之间,四是平放于耐热钢工装上。
In the heat treatment of forgings, the way to reduce the deformation of parts, one is to hang vertically as far as possible, two is vertically placed at the bottom of the furnace, three is supported by two points, the position of the fulcrum is between 1/3 and 1/4 in length, and four is flat on the heat-resistant steel.

 在零件的冷却过程中,淬火介质的种类、冷却性能、淬硬性等与变形有关。冷却性能的变化可通过改变介质的黏度、温度、液面压力、使用添加剂、搅拌等进行调节。淬火油的黏度越高,温度越高,椭圆形变形越小。在静止状态下,变形较小。
In the cooling process of parts, the types, cooling properties and hardenability of quenching medium are related to deformation. The change of cooling performance can be adjusted by changing the viscosity, temperature, liquid surface pressure, additives and agitation. The higher the viscosity of quenching oil, the higher the temperature, the smaller the elliptical deformation. In the static state, the deformation is small.

  以下几种方式可有效降低钣金加工变形:①盐浴淬火;②高温油淬火;③QSQ法;④减压淬火;⑤一槽三段淬火。盐浴淬火和高温油淬火相似,都是在马氏体转变温度处淬火,使马氏体相变的均匀性增加。QSQ是双液淬火。减压淬火是通过降低淬火介质的液面压,从而延长蒸汽膜阶段,高温区的冷却速度下降,使零件各部分的冷却速度均匀。一槽三段淬火结构简单,首先将零件从淬火温度油冷至略高于Ms点的温度,随后出炉,在气氛中保持,使零件整体温度均匀,然后再油冷,使马氏体相变均匀进行,变形的不规则性得到极大的改善。

The following methods can effectively reduce the deformation of sheet metal processing: (1) salt bath quenching; (2) high temperature oil quenching; (3) QSQ method; (4) vacuum quenching; three quenching of one groove. Salt bath quenching and high temperature oil quenching are similar, all are quenched at martensitic transformation temperature, so that the uniformity of martensitic transformation is increased. QSQ is double liquid quenching. By reducing the pressure of the liquid surface of the quenching medium, the pressure reduction process extends the phase of the steam film, and the cooling rate of the high temperature zone decreases and the cooling rate of the parts of the parts is uniform. The three section quenching structure is simple. First, the part from the quenching temperature oil is cold to a little higher than the Ms point. Then, the temperature of the part is kept in the atmosphere, the whole temperature of the part is uniform, then the oil is cooled, the martensite transformation is carried out evenly, and the irregularity of the deformation is greatly improved.


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