汽车零件用热冲压硼合金钢

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新手报道，
找了篇文章翻翻，算是给各位大虾当见面礼。图片懒的上传了。。。GOOGLE把。。。不然直接问我要好了。。。
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STAMPING JOURNAL®
Hot-stamping boron-alloyed steels for automotive parts
汽车零件用热冲压硼合金钢
By Taylan Altan
Part I: Process methods and use
第一部分: 过程方法和应用
December 12, 2006
Hot-stamped parts are being used increasingly in cars in Europe and North America. Ultrahigh-strength steels, like boron alloys, which meet automotive safety and crash requirements, are difficut to form with cold stamping, so hot stamping with die quenching has been applied.
热冲压件在欧洲和北美的汽车制造业中的使用不断增长。超高强度钢，如可以满足汽车安全和碰撞要求的硼合金钢，很难以冷冲压的方式成型，而热冲压及其模具冷却得以应用。
Editor's Note: This article is Part I of a three-part series discussing hot stamping of boron steels. Part II, which will appear in the January 2007 issue, will discuss the microstructure of boron steels and coatings on the sheet surface. Part III, which will appear in February 2007, will cover the application of finite element (FE) simulation to the hot-stamping process.
编者按： 本文第一部分讨论硼钢的热冲压；第二部分将于2007年一月发表，讨论硼钢的微观结构和钢板表面镀层；第三部分将于2007年二月发表，将概述限元模拟在热冲压过程中的应用。
This column was prepared by the staff of the Center for Precision Forming (CPF) (formerly called ERC/NSM - Engineering Research Center for Net Shape Manufacturing), The Ohio State University and Professor Taylan Altan, director.
本专栏由美国俄亥俄州州立大学和Taylan Altan教授带领的精密成型中心（CPF）小组成员准备（该中心曾名为ERC/NSM，净成型技术研究中心）
Thanks to steadily rising vehicle safety and crash requirements in the automotive industry, the use of ultrahigh-strength steels in structural and safety components is rapidly increasing. The higher requirements for vehicle crash performance can be achieved with cold stamping only by using thick-gauge steel, which results in weight increase. Cold stamping allows the production of simple shapes with very high strength, up to 1,200 megapascals (MPa) (about 175 kilopounds per square inch), such as side impact beams.
由于汽车制造业对汽车安全性和冲撞要求的不断提高，超高强度钢在结构件和安全件的使用迅速增加。冷冲压件要在汽车冲撞试验中达到较高要求只有增加钢材的厚度，而随之带来的影响则是重量的增加。用冷冲压的方法可以使形制简单的零件具有很高的强度，可达到1200MPa。
Ultrahigh-strength steels, however, pose a major challenge in processing because of their limited formability and pronounced springback at room temperature. So, when part complexity increases, such as with B-pillars, only lower-strength steel grades can be used with cold stamping.
另一方面，超高强度钢由于其有限的成型能力和显著的反弹效应在加工方面的则遇到了重要的挑战。因此，当零件的复杂性增加时，如中立柱，只能用较低强度的材料进行冷冲压。
Figure 1
Tensile strength and microstructure change during hot stamping. 热冲压时拉伸强度和微观结构的变化。
Components with strength less than 1,000 MPa (about 145 KSI) and complex shapes are manufactured in several steps using progressive dies or transfer presses. Figure 1 shows a classification of steels according to their strength and elongation properties.
1000MPa形状复杂的零件是通过几道工序、使用级进模或连续模来完成的。图1显示钢材按其强度和延伸率的分类。
Hot stamping with die quenching of boron steels appeared at the end of 1990s for producing some rather simple automotive parts like door beams and bumper beams. This process can overcome some of the typical difficulties associated with cold stamping.
用硼钢热冲压和模具冷却的工艺出现在90年代后期，起初是用于制造一些相对简单的汽车部件，如门梁和保险杠。这种工艺能够克服一些冷冲压的典型难点。
For example, hot-forming of the quenchable boron-alloy steel 22MnB5 can produce complex, crash-resistant parts such as bumpers and pillars with ultrahigh strength, minimum springback, and reduced sheet thickness (see Figure 2). The tensile strength of boron steels is up to 1,600 MPa (about 230 KSI), which is far above that of the highest-strength conventional cold stamping steels.
例如，用具有急速冷却特性的硼合金钢22MnB5进行热冲压，可以生产形状复杂，抗冲撞的零件，如保险杠和立柱。零件具有超高强度，反弹性小且材料厚度降低的特点（见图2）。硼钢的拉伸强度可以达到1600MPa, 远远高于普通冷冲压钢材的最高强度。
Figure 2
In hot stamping, forming and hardening are combined in a single operation. Two different methods are used: direct and indirect. Source: H. Engels, O. Schalmin, and C. Müller-Bollenhagen, “Controlling and Monitoring of the Hot-Stamping Process of Boron-Alloyed Heat-Treated Steels,” in proceedings from The International Conference “New Development in Sheet Metal Forming Technology,” Stuttgart, Germany, 2006, pp.135-150.
在热冲压过程中，成型和固化合成为一个单一的步骤。两种不同的方法应用在热冲压构成中：直接法和间接法。信息来源：H. Engels, O. Schalmin, 和 C. Müller-Bollenhagen 《硼合金热处理钢的热冲压过程》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp.135-150
Hot-Stamping Process
热冲压过程
In hot stamping, forming and hardening are combined in a single operation. Two different methods are used: direct and indirect.
在热冲压过程中，成型和固化合成为一个单一的步骤。两种不同的方法应用在热冲压成型中：直接法和间接法。
Direct Method. In the direct method (Figure 2a), the blanks are austenitized at temperatures between 900 and 950 degrees Celsius for four to 10 minutes inside a continuous-feed furnace and subsequently transferred to an internally cooled die set via a transfer unit. At high temperature (650 to 850 degrees C), the material has excellent formability, so that complex shapes can be formed in a single stroke.
直接法：（见图2a），落料在900到950摄氏度形成奥氏体，在连续炉中经过4-10分钟后立刻转移至一个通过传送单元进行自冷却的模具内。在高温（650到850摄氏度）的条件下，材料有很好的塑性。因此，形状复杂的零件得以一次成型。
The blanks are stamped and cooled down under pressure for a specific amount of time according to the sheet thickness after drawing depth is reached. During this period the formed part is cooled in the closed die set that is internally cooled by water circulation at a cooling speed of 50 to 100 degrees C per second, completing the quenching (martensitic transformation) process.1
根据材料的厚度，当其拉伸深度达到后，保持一定时间的压力，冲压落料并使其冷却。在这个阶段，成型的工件在密闭的模具中冷却，模具本身依靠水循环进行冷却，水冷却的速度在50-100摄氏度/秒，这一过程即淬火(形成马氏体)过程1。
The total cycle time for transferring, stamping, and cooling in the die is 15 to 25 seconds. Finally, the part leaves the hot-stamping line at about 150 degrees C and with high mechanical properties: an ultimate tensile strength of 1,400 to 1,600 MPa (about 200 to 230 KSI) and a yield strength between 1,000 and 1,200 MPa (about 145 to 175 KSI).2
在模具中，一个传送、冲压、冷却的过程需要15-25秒。最后工件离开热冲压线时的温度在150摄氏度，且具有很好的机械性能：最高拉伸强度为1400-1600PMa，屈服强度在1000-1200MPa. 2
Indirect Method. Unlike the direct process, indirect hot stamping provides for a part to be drawn, unheated, to about 90 percent to 95 percent of its final shape in a conventional die, followed by a partial trimming operation, depending on edge tolerance (see Figure 2b).
间接法：不同于直接法，间接热冲压的工件90%-95%的成形在常温模具下完成，之后根据边缘公差，还要部分整形（见图2b）。
Then the preforms are heated to austenitization temperature in a continuous furnace and hardened in the die. The reason for the additional step is to extend the forming limits for very complex shapes by heat-treating the cold-formed parts. 3
之后，在连续炉内加热工件到形成奥氏体的温度，使之在模具固化。增加一个步骤的原因是热处理冷冲压件以扩大较复杂形状工件的塑性极限。3
Increasing Use 广泛的应用
Figure 3 图3
Hot stamping has shown exceptional development and growth for several structural parts, including front and rear bumper beams, A-pillars, B-pillars, roof rails, side rail members, tunnels, and door beams.
热冲压在某些结构件上的应用发展迅速，且有显著增长。其中包括前后保险杠，前立柱，中立柱，顶梁（C柱？）SIDE RAILE，TUNNEL, 门加强筋
Most North American and European car manufacturers now are specifying hot-stamped parts for their new vehicles to take advantage of the superior strength achieved by hot forming and quenching. Hot stamping has shown exceptional development and growth for several structural parts, including front and rear bumper beams, A-pillars, B-pillars, roof rails, side rail members, tunnels, and door beams (see Figure 3).
现在多数北美和欧洲汽车制造厂看重热冲压和快速冷却达到的高强度，将热冲压件专门用于其新车。热冲压在某些结构件上的应用发展迅速，且有显著增长。其中包括前后保险杠，前立柱，中立柱，顶梁（C柱？）SIDE RAILE，TUNNEL, 门加强筋。（见图3）
In 2004 the estimated total consumption of flat boron steels for hot stamping and die quenching was about 60,000 to 80,000 tons per year in Europe. In 2008-2009 yearly consumption in Europe is expected to increase to about 300,000 tons. Japan and North America are following this trend.
2004年欧洲用于热冲压模具冷却的硼钢板材的预计总消耗量为6-8万吨/年。2008-2009年欧洲的年消耗量预计约为30万吨。日本和北美也在顺应这个趋势。
Expectations are for more than 20 new hot-stamping lines (heating furnace and press) to be built between 2004 and 2009 throughout the world.4
预计2004-2009年全球有超过20条新的热冲压线（加温炉和压机）建成。4
Notes:
1.        P. Hein et al, "Hot Stamping of USIBOR 1500P: Part and Process Analysis Based on Numerical Simulation," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2006, pp. 163-175.
P. Hein et al 《USIBOR 1500P热冲压: 基于数字模拟的产品和过程分析》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp 163-175.
2.        Ibid.
3.        T. Tröster and W. Rostek, "Advanced Hot Forming," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2004, pp. 49-63.
T. Tröster 和 W. Rostek 《先进的热成型》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 49-63.
4.        R. Kolleck et al, "Hot Forming and Cold Forming — Two Complementary Processes for Lightweight Auto Bodies," in proceedings fromThe International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2004, pp. 235-244.
R. Kolleck et al 《热成型和冷成型—两种当代减轻车身重量的工艺》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp235-244.


Part II: Microstructure, material strength changes during hot stamping
第二部分: 热成型过程中微观结构和材料强度的变化
January 18, 2007
Compared with cold-formed parts, hot-stamped parts provide better formability at high temperatures and exhibit no springback on the final part.
与冷冲压件相比，热冲压件在高温下有更好的成型性能并且最终产品不会回弹。

To reduce weight in automotive body design, OEMs use conventional lightweight materials such as aluminum, magnesium, and polymers, but the use of ultrahigh-strength steels also is increasing. Conventional cold-stamping methods and microalloyed boron steel (22MnB5) processing can be performed with a nonisothermal hot sheet metal forming process called direct hot stamping. This new process combines hot forming and subsequent quench hardening in a single process step.
在车身设计中，为了降低重量，整车制造厂使用常规轻质材料，如铝、镁和工程塑料（聚合物）。不过对于超高强度钢材的使用也开始增长。常规冷冲压方法和含硼微合金钢(22MnB5)加工可用于非等温热金属板成型工艺，这种工艺称之为热冲压。这种工艺结合了热成型和随即淬火硬化，使之在一道工序中完成。
Hot stamping is compatible with boron-alloyed steel's chemical composition, because it creates a robust process window for quenching, which causes martensitic transformation.1,2 Boron steels belong to a group of martensitic steels with good hardenability at low cooling rates.
热冲压与硼钢的化学成分匹配，由于硼钢能产生稳定的淬火过程，使其转化为马氏体。1,2　硼钢属于在低冷却速度时具有较好淬透性的马氏体钢。
The base material, 22MnB5, has a ferritic-pearlitic microstructure with a tensile strength of approximately 600 megapascals (MPa) (87 ksi). After the part is hot-stamped, it has a martensitic microstructure and increased strength, up to 250 percent of its initial value.2 This technology offers considerable potential for minimizing component weight by reducing sheet thickness and the number of components needed. Hot-stamping technology can be used for A- and B-pillar reinforcements, roof rails, side-wall members, and beams for crash management structures.3 Compared with cold-formed parts, hot-stamped parts provide better formability at high temperatures and exhibit no springback on the final part.
22MnB5的基板的微观结构呈现铁素体-珠光体，此时的拉伸强度接近600MPa。工件经过热冲压之后，其微观结构呈现马氏体，而强度比最初值上升250%。2 这一技术为降低板材厚度、减少零件数量从而减少零件重量提供了巨大的潜力。热冲压技术可用于制造A柱、B柱加强筋，车顶纵梁、车围构件以及各种防冲撞的横梁结构。较之冷冲压件，热冲压件在高温下有更好的成型性能，并且最终产品不会回弹。
Metallurgical Fundamentals
金相结构
Hot-stamping metallurgy starts with austenitizing sheet blanks or preformed geometries in a continuous-feed furnace for approximately five to 10 minutes at temperatures between 900 degrees C and 950 degrees C. This procedure creates a homogeneous austenitic microstructure. Blanks then are quickly transferred into a cooled stamping die using an automatic feeding system. This transfer generally takes less than three seconds.
热冲压的金相变化过程如下：板材或立体工件在900-950摄氏度的连续炉中加热约5-10分钟使之奥氏体化；这一过程形成均匀的奥氏体结构。板料随即快速转移至安装自动冷却系统的冲压模具。这一转移过程通常小于3秒种。
Figure 1
Tensile strength and microstructure change during hot stamping. 热冲压过程中拉伸强度和微观结构变化
At high temperatures of 650 degrees C to 850 degrees C, the material has excellent formability and can be formed into a complex shape in a single stroke. Quenching takes place simultaneously or right after forming. During quenching, the austenitic microstructure transforms into a martensitic one because of rapid cooling (between 50 degrees C/second and 100 degrees C/second). As a result of this microstructural change, component tensile strength of more than 1,500 MPa (218 ksi) is possible.1-5 Because the part remains in the die during the cooling stage, springback is minimized. Figure 1 illustrates an overview of the hot-stamping process sequence.
在650-850摄氏度的高温下，材料具有最佳的塑性，能够通过一次冲压形成复杂的形状。冲压过程中同时淬火或之后立即淬火。在淬火过程中，由于急剧冷却（冷却速度可以达到50-100摄氏度/秒），奥氏体转化成马氏体。由于金相结构的变化，零件的拉伸强度可能达到1500 MPa1-5。由于工件冷却的时候是在模具中，回弹值很小。图1显示整个热冲压的加工过程。
Boron-alloyed Steel Coatings
硼钢镀层
If a sheet blank is not coated, heating must be done in a protective atmosphere to avoid oxidation (scaling) and surface decarburization. However, when uncoated boron steel is transferred from the furnace to the press, an irregular and abrasive iron oxide layer forms on the blank's surface.
如果板料没有镀层，加热过程就必须在保护性气体中完成，以防止氧化（脱落）和表面脱碳。但是没有镀层的硼钢从连续炉转移到压机，其工件表面会形成不规则的，可磨去的氧化铁层。
Because of this direct contact with atmospheric oxygen, oxidation occurs. In this case, it's impossible to avoid some superficial decarburization (up to 60 µm), which is detrimental to a part's final properties.1 Since the scale is characterized by extreme hardness, movement between the die and ultrahigh-strength blank during hot stamping may result in high die wear.
由于直接和氧气接触，便发生这种氧化反应。在这种情况下，几乎不可避免形成表面脱碳现象（可达到60 µm），而这对于产品最后的性能是不利的。1，由于脱落的物质硬度很大，这些物质在热冲压的过程中，在模具和超高强度材料之间的移动可能会损坏模具。
Moreover, these parts should be shotblasted or sandblasted to remove the scale layer. Shotblasting is expensive and can be harmful to thin parts' geometric tolerances. This scaling during hot stamping can be avoided by using an aluminum-silicon surface coating. For example, Usibor, a 1500P fine-grain alloy developed by Arcelor, has homogeneously distributed ferritic-pearlitic microstructure. This precoated boron steel has an aluminum-silicon-based layer that is between 23 µm and 32 µm thick.1,2
此外，这些工件必须经过抛丸或喷沙处理，以去除脱碳层。抛丸的成本比较贵，且对于较薄零件的尺寸公差有影响。在热成型的过程中，通过给材料使用铝硅表面镀层，脱碳现象是可以避免的。例如，Usibor,1500P 细颗粒合金，由Arcelor研发。这种材料铁素体-珠光体结构分布均匀，其表面镀有23 - 32 µm 铝硅基镀层。
Figure 2 图2
During heating, a protective coating is transformed into an alloyed layer of Fe-Al-Si that is highly adherent to the substrate and has good corrosion properties.1
材料加热以后，保护层变为铁铝硅合金层，强力附着在基板上，因而具有很好的腐蚀性能1
During heating, this protective coating is transformed into an alloyed layer of Fe-Al-Si that is highly adherent to the substrate and has good corrosion properties (see Figure 2). The hot-stamped Usibor 1500P parts are ready to be painted without shotblasting (no scale). They have excellent geometric tolerances and do not show any decarburization because of the coating's protective effect in the furnace.1 Usibor 1500P provides technical and economical advantages in product development for hot stamping.
材料加热以后，保护层变为铁铝硅合金层，强力附着在基板上，因而具有很好的防腐蚀性能（见图2）。热冲压的Usibor 1500P零件无须抛丸处理（没有氧化铁碎屑）可直接喷涂，能够保证良好的尺寸公差。由于炉内保护镀层的作用，不会产生脱碳现象。1  Usibor 1500P在热冲压产品发展上具有技术和经济的优势。
Usibor 1500P is used for the pillars and sills of the new VW Passat® and the Mercedes S Class; for A-pillars in the Land Rover; and bumper beams in the Ford Mustang®.1 Hot stamping precoated boron-alloyed steel 22MnB5 is increasingly being used in new European and American cars.
Usibor 1500P 已用于大众新帕萨特®和奔驰S级的立柱和横梁构件。路虎的A柱，福特Mustang®的保险杠。1 而热冲压用镀层硼钢22MnB5在新款欧美车型上的使用也日益增加。
Notes:
1.        P. Hein, R. Kefferstein, and Y. Dahan, "Hot Stamping of USIBOR 1500P: Part and Process Analysis Based on Numerical Simulation," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2006, pp. 163-175.
P. Hein, R. Kefferstein, 和Y. Dahan, 《USIBOR 1500P热冲压：基于数字模拟的产品和过程分析》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 163-175.
2.        M. Merklein, J. Lechler, and M. Geiger, "Characterisation of the Flow Properties of the Quenchenable Ultra High Strength Steel 22MnB5," Annals of the CIRP, Vol. 55 (2006), Kobe, Japan.
M. Merklein, J. Lechler,和 M. Geiger, 《可淬火超高强度钢22MnB5的流动性特征》，CIRP纪录，Vol. 55 (2006)，神户，日本
3.        R. Kolleck et al, "Hot Forming and Cold Forming — Two Complementary Processes for Lightweight Auto Bodies," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2004, pp. 235-244.
R. Kolleck et al 《热成型和冷成型—两种当代减轻车身重量的工艺》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp235-244.
4.        H. Engels, O. Schalmin, and C. Müller-Bollenhagen, "Controlling and Monitoring of the Hot-Stamping Process of Boron-Alloyed Heat-Treated Steels, in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2006, pp. 135-150.
H. Engels, O. Schalmin 和C. Müller-Bollenhagen, 《监控热热处理硼钢的冲压过程》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 135-150.
5.        R. Neugebauer, T. Altan, M. Geiger, M. Kleiner, and A. Sterzing, "Sheet Metal Forming at Elevated Temperatures," Annals of the CIRP, Vol. 55 (2006), Kobe, Japan.
R. Neugebauer, T. Altan, M. Geiger, M. Kleiner, 和 A. Sterzing 《高温板材成型》，CIRP纪录，Vol. 55 (2006)，神户，日本

Part III: Tool design and process simulation
第三部分: 模具设计和过程模拟
February 13, 2007
To accurately model the hot-stamping process, FE simulation needs to account for the mechanical, thermal, and microstructural changes in the workpiece.
为精确模拟热冲压的过程，有限元模拟需要解决工件的机械、温度和微观结构的变化。
Figure 1 图1
The challenge in FE simulation is developing a material model that can accurately account for the interaction of the mechanical, thermal, and microstructural data.1
有限元分析的难点即开发一种材料模式，使其能精确的表现出机械、温度和微观结构数据的相互变化。
Hot stamping comprises a forming process and then cooling the formed part within the die. Finite element (FE) simulation of hot stamping is currently under development. To model the hot-stamping process accurately, FE simulation needs to predict the mechanical, thermal, and microstructural changes in the workpiece (see Figure 1).
热冲压包括工件的成形过程和其在模具中冷却的过程。热冲压的有限元模拟则是新兴发展起来的。为了精确地还原热冲压过程，有限元模拟需要预测工件的机械、温度和微观结构的变化。
Material data is needed over a range of forming temperatures (600 degrees C to 900 degrees C) and deformation rates to conduct reliable process simulations. Changing surface conditions during forming (such as formed scale on the sheet surface) significantly influence heat transfer as well as friction between the workpiece and tool.
我们需要了解成形温度（600-900摄氏度之间）和变形速度的材料数据，以便可靠地模拟过程。成形中表面条件的改变（板材表面形成碎屑）极大地影响热量的转移以及共建和模具之间的摩擦。
Forming Process Simulation
成形过程模拟
Figure 2a & 2b
2a An isothermal FE analysis at 700 degrees C indicates the location of maximum thinning. 2b A thermomechanical simulation provides more accurate predictions, because it accounts for workpiece temperature gradients as well as the effect of forming speed.2
2a 700摄氏度时等温有限元分析显示最大变薄处的位置。2b 温度-机械性能模拟提供更稳精确的预测，工件的温度变化和成形速度的影响的以表现。
Because forming a heated workpiece occurs quickly (forming speeds are approximately 500 mm per second), a simplified isothermal analysis could be made assuming no temperature changes occur during actual deformation. However, workpiece cooling in the die must be considered assuming that nearly all the cooling occurs after the part is hot-formed.
由于加工一个温度很高的工件在短时间内完成（成形速度约为500mm/秒），可假设在一个形变过程中，没有温度变化，因而使用简单的等温分析。但是工件的冷却则必须考虑这样一个假设：冷却的过程发生几乎都在热成型后。
Figure 2a shows results from an isothermal hot-forming FE simulation of a B-pillar. In an isothermal analysis, a single flow stress curve and friction coefficient are input to figure the finite element method (FEM). Temperature and the effect of forming speed are not accounted for.
图2a显示了B柱等温热成型有限元分析的结果。在等温分析中，输入一个简单的流变曲线和摩擦系数可作为有限元算法。温度和成形速度的影响不做考虑。
Figure 2b shows results for a thermomechanical FE simulation. This FE simulation considers the temperature gradients within the material, as well as the effect of forming speed and heat transfer between the tools and the workpiece.
图2b显示B柱温度-机械有限元模拟的结果。这一模拟考虑材料的温度变化以及形变速度的影响和模具和工件之间热量转移的影响。
Microstructural changes, such as transformation to martensite, are not considered in this analysis. Research in predicting and modeling microstructural changes in a workpiece using FEM is in progress. 2
微观结构的变化，如形成马氏体，在这个分析中则不作考虑。利用有限元分析的方法预测和还原工件的微观结构变化尚待进一步发展。
Cooling Process Simulation
冷却过程模拟
After the forming process is completed, the part must be cooled as quickly and homogeneously as possible. As discussed in the December 2006 issue, the hot-formed part is quenched within a closed die at a cooling rate of approximately 50 degrees C to 100 degrees C per second.
成型过程完成之后，工件必须尽快并且均匀冷却。正如2006年12月期刊所讨论过的，热成型件在闭合的摩举重淬火，其冷却速度接近50-100摄氏度/秒。
Figure 3a & 3b
Thermal FE analysis can predict punch and die temperature distribution during the cooling process. Holes drilled in the die allow for faster cooling.
温度有限元分析可以预测冷却过程中冲床和模具温度的分布，模具中冲孔的冷却速度比较快。
Tool design is particularly critical during the cooling process. The die must absorb and dissipate a significant amount of heat energy through integrated cooling channels. Cooling channels should be designed to achieve a homogeneous distribution of mechanical properties in the formed part.
冷却过程中模具设计尤为重要。模具必须通过其自带的冷却系统吸收并带走大部分热能。设计冷却系统时，要使其在成型工件上均匀分布。
Thermal FE analysis can assist tool designers in estimating temperature distribution within a workpiece and tool. Figure 3a and Figure 3b show the temperature distribution for two tools with different cooling channel designs. The die shown in Figure 3a has an additional drilling hole. A comparison of temperature distribution between two cooling designs shows that cooling capacity is improved by drilling an additional hole. Figure 3c illustrates a formed part's temperature distribution.
温度有限元分析可以辅助模具设计者估计温度在工件和模具内的分布。图3a和图3b显示了两组带有不同冷却系统设计的模具的温度分布。图3a增加了一个冲孔，比较两个冷却系统设计的温度分布可以显示，增加冲孔的设计其冷却能力得到了提升。图3c显示成型工件的温度分布。
Figure 3c
FE analysis can predict temperatures in a formed part, so cycle time for hot stamping can be estimated.3
有限元分析可以预测成型工件的温度，因此可以估算热冲压的周期时间3
An insufficient cooling rate because of poor tool design can be predicted and corrected using FE simulation. Besides temperature distribution, thermal FE analysis also can be used to predict the cycle time required to cool a part to approximately 150 degrees C. At this temperature, a part can be safely withdrawn from the die. Thus, a controlled and optimized hot-stamping process can be developed with FE analysis. 3
使用有限元分析，可以预测因设计缺陷而导致的冷却速度不足。此外温度分布，温度有限元分析可以预测将工件冷却至150摄氏度左右的周期时间，工件在这个温度可以安全地从模具中取出。有限元分析的使用有利于控制和优化热成冲压过程的发展。
Until now most of the research related to FE simulation of hot stamping has been done in Europe. However, the Center for Precision Forming (formerly ERC/NSM) also is conducting warm-forming simulations. The CPF also has extensive experience in the simulation and modeling of hot- and warm-forging processes, which are similar to hot stamping.
迄今为止，大多数关于热冲压的有限元模拟研究都是在欧洲完成的。精密成形中心（以前的ERC/NSM）也开始实施温热成型模拟的研究。精密成形中心在模拟和还原热锻和温锻方面经验丰富，而这个工艺与热冲压非常相似。
Notes:
1.        T. Tröster and W. Rostek, "Advanced Hot Forming," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2004, pp. 49-63.
   T. Tröster 和 W. Rostek 《先进的热成型》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 49-63.
2.        P. Hein, R. Kefferstein, and Y. Dahan, "Hot Stamping of USIBOR 1500P: Part and Process Analysis Based on Numerical Simulation," in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2006, pp. 163-175.
   P. Hein, R. Kefferstein, 和Y. Dahan, 《USIBOR 1500P热冲压：基于数字模拟的产品和过程分析》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 163-175.
3.        H. Engels, O. Schalmin, and C. Müller-Bollenhagen, "Controlling and Monitoring of the Hot-Stamping Process of Boron-Alloyed Heat-Treated Steels,"; in proceedings from The International Conference "New Development in Sheet Metal Forming Technology," Stuttgart, Germany, 2006, pp. 135-150.
    H. Engels, O. Schalmin 和C. Müller-Bollenhagen, 《监控热热处理硼钢的冲压过程》选自国际会议《金属板成型技术新发展》会议记录，Stuttgart, 德国, 2006, pp. 135-150.

[ 本帖最后由 moumouren 于 7-2-2008 21:59 编辑 ]