卷取温度对热冲压成型钢组织及性能的影响

通过淬火实验对比分析了薄板坯连铸连轧工艺(FTSR)生产的同规格不同卷取温度的热冲压成型钢的组织和性能。结果表明,试样组织主要由铁素体+珠光体组成,750℃卷取时热冲压成型钢出现严重带状组织,620℃卷取时热冲压成型钢带状组织级别减小。利用相变仪实验得出卷取温度对热冲压成型钢奥氏体化及最终组织的影响很小,得到的组织均为马氏体+极少量铁素体组织。模拟工业生产进行淬火、回火热处理后,组织都属于板条状马氏体,组织均匀,进行拉伸实验后,性能差异不大。两种卷取温度下生产的带钢在热处理后获得了相近的组织及性能。     

热送中厚板生产线钢板表面裂纹的机理分析

在中厚板生产过程中,采用热送热装工艺能降低能源消耗、减少氧化烧损、提高产量,但也会使钢板表面的裂纹增加,对中厚板热装生产中裂纹产生的机理进行了分析.     

无缺陷连铸异型坯生产及其热送热装技术研究

通过对异型坯连铸工艺的优化、结晶器保护渣性能和连铸设备的改进,解决了连铸异型坯容易产生的表面纵向裂纹、表面横向裂纹、表面划痕和腹板中心线裂纹等质量问题,使异型坯质量大大提高,为连铸异型坯热送热装创造了条件。通过对生产调度系统的改进,实现了异型坯热送热装轧制,异型坯热送热装使热轧H型钢产量增加,能耗下降,经济效益显著。     

热送热装工艺的研究

热送热装是一种节能降耗工艺,对传统工业结构的改革具有深远的意义。但在实际生产中,该工艺会使钢坯/钢锭产生红送裂纹。铸坯/钢锭在凝固后的冷却过程中,会发生C、N化合物析出于奥氏体晶界,削弱晶界能,导致A→F相变,体积膨胀加剧了晶界强度的减弱,在轧制时就会扩展形成表面裂纹。因此,需要制定合理的热送工艺和加热工艺,以保证热送热装工艺的顺利实施。     

20G无缝钢管的热浸渗铝工艺

对20G无缝钢管的热浸渗铝工艺进行了研究和试验。测定了不同工艺条件下获得的浸渗层深度和浸渗层显微硬度的分布。在对渗铝钢管进行金相、SEM和能谱分析后,确定了热浸渗铝的基本工艺参数。此外,对解决铝液表面氧化烧损和坩埚内壁腐蚀问题提出了参考意见。     

裸板热成型表面状态对氧化铁皮影响因素分析

本文对不同表面状态的裸板热成型钢板进行了热成型工艺的模拟,通过对表面氧化铁皮微观形貌以及线扫描,对比微观组织结构与组分的差异,找出氧化铁皮脱落的原因,同时通过对比试验不同表面状态对氧化铁皮脱落程度的影响规律。     

00Cr19Ni10不锈钢热穿孔开裂成因分析与对策

通过对报废的荒管进行常规检测分析,结合热穿孔过程成型机理,揭示了穿孔内表面裂纹的主因是弥散在基体中硅酸盐夹杂物、α相的偏高以及热穿孔工艺不合理;据此提出了改进措施和方法,为其后续生产提供指导和借鉴。     

良加工热镀铝锌钢板表面摩擦特性及冲压成型性能研究

为满足家电户外件对热镀铝锌耐指纹钢板冲压成型性的需求,开发了一种具有优异冲压成型性的热镀铝锌耐指纹钢板,并通过摩擦因数分析仪和冲压试验机研究了室温及高温条件下其表面摩擦特性及冲压成型性能。结果显示,在室温及高温(100℃)条件下,热镀铝锌耐指纹钢板均能够保持较低的动摩擦因数,表明其具有良好的表面润滑性能及稳定的摩擦特性。冲压成型后,热镀铝锌耐指纹钢板受力变形区域表面无明显犁痕、发黑和脱锌现象,表明其具有优异的冲压成型性能。     

热浸镀工艺对热成形钢铝硅镀层的影响

随着汽车轻量化的不断发展,热成形钢得到越来越快的发展,普通镀层已满足不了热成形工艺的要求。热浸镀铝硅钢板具有优良的耐热耐腐蚀性能、抗高温氧化性能和外观装饰性能等,得到普遍的应用。目前国内对铝硅镀层研究甚少,国内汽车制造厂使用的镀铝硅热冲压成形钢主要依靠进口。利用CAG-III热浸镀锌模拟试验机,针对不同热浸镀工艺对热成形钢板进行热浸镀铝硅试验,通过扫描电镜等手段进行表面和截面形貌观察及能谱分析。试验结果表明,铝硅镀层截面组织主要由铝基固溶体、Al-Fe-Si三元合金和Fe-Al二元合金组成,当浸镀温度为690 ℃、浸镀时间为5 s时为最优浸镀工艺。     

湘钢连铸坯热送热装工艺实践

通过湘钢公司热送热装工艺的实践，介绍热送热装过程中应注意的几方面问题及节能降耗的意义。     

热冲压钢镀层技术的研究现状

简要介绍了汽车用钢热冲压工艺技术的特点及其对镀层的性能要求,在此基础上着重描述了近年来国内外热冲压钢镀层技术的研究进展,详细列出了Al-10Si镀层的使用性能及GI(Galvanized)、GA (Galvanealed)镀层的研究状况.针对热冲压钢镀层产品的使用现状和未来需求方向,指出除了Al-10Si镀层外,发展GI/GA热冲压镀层技术是未来热冲钢发展的一个重要方向.     

Some Highlights on New Steel Products for Automotive Use

This paper is a short review on some recent developments regarding steels for automotive use. A new precoated steel suitable for to hot stamping processing has been developed, which is most appropriate for producing anti‐intrusion parts. Another evolution of precoated steels is a new inorganic treatment (NIT), which has proved to be efficient in increasing the stamping productivity of precoated steels. In the field of corrosion protection, a new generation of thin organic coatings has been implemented and in the future Zn‐Mg metallic coatings will help to save auxiliary anticorrosion measures such as wax and mastics. To offer steels with high stiffness but low weight, Arcelor has developed a new multimaterial sandwich which shows a good potential for large panels due to its high stiffness. Finally, some breakthrough steel products are discussed as possible candidates for mid/long term applications.     

State‐of‐the‐Knowledge on Coating Systems for Hot Stamped Parts

In the present contribution, recent developments of coatings for hot stamped steels are reviewed. The use of bare steel in the initial hot stamping technology is discussed, including the application of lubricant oils which are used as oxidation inhibitors on bare steel surfaces. The aluminized coatings are introduced, focusing on the microstructure evolution of aluminized coatings during the hot stamping process. An analysis of the cracking of the coating, caused by the formation of brittle Fe–Al intermetallic phases and their high temperature deformation, is presented. The development of a ductile aluminide coating formed during the diffusion treatment of an aluminized coating is discussed. This aluminide coating can endure both high temperature oxidation and severe plastic deformation. The recently developed galvanized and galvannealed coatings are also reviewed and the influence of the gas atmosphere during the heating cycle on the coating stability is emphasized. The solutions which have been proposed to avoid liquid Zn‐induced embrittlement are analyzed. The use of Zn–Ni alloy coating, which is characterized by a higher melting temperature, is reviewed. The behavior of sol–gel hybrid coatings on hot stamped steels is discussed. The possible use of the recently developed Al–Zn alloy coatings, dual layer Zn–Al and Zn–Al–Mg coatings is also introduced. The application of Zn–Al–Mg post‐process galvanizing is also discussed. In each case, all available information related to the weldability, paintability, and corrosion resistance of the coating systems is also reported. Finally, the advantages and technical challenges associated with each type of coating are reviewed.     

Influence of Hot Press Forming Techniques on Properties of Vehicle High Strength Steels

  Based on the combination of materials science and mechanical engineering, hot press forming process of the vehicle high strength steels was analyzed. The hot forming process included: heating alloys rapidly to austenite microstructures, stamping and cooling timely, maintaining pressure and quenching. The results showed that most of austenite microstructure was changed into uniform martensite by the hot press forming while the samples were heated at 900 ℃ and quenched. The optimal tensile strength and yield strength were up to 1530 MPa and 1000 MPa, respectively, and the shape deformation reached about 23%. And springback defect did not happen in the samples.     

热冲压技术应用现状与发展前景

随着汽车轻量化的发展,迫切需要在不降低汽车零部件性能的前提下,开发一些新工艺来减轻零件的重量。钢板热冲压是一种将先进高强度钢板加热到奥氏体温度后快速冲压,在保压阶段通过模具实现淬火并达到所需冷却速度,从而得到组织为马氏体、强度在1 500MPa左右的超高强度零件的新型成形技术。对钢板热冲压新技术的关键装备、核心技术和优缺点以及使用现状等做了系统介绍,并预测了热冲压技术的未来发展趋势。     

Corrosion Resistance of Different Metallic Coatings on Press‐Hardened Steels for Automotive

The corrosion resistance of laboratory press‐hardened components in aluminized, galvanized or galvannealed boron steels was evaluated through VDA 621‐415 cyclic test for the automotive industry. 22MnB5 uncoated steel for hot stamping and standard galvanized steel for cold forming were also included as references. Corrosion resistance after painting (cosmetic corrosion) was quantified by measuring the delamination of electro‐deposited paint from scribed panels. The rusting on their edges was used for determining the cut‐edge corrosion resistance. The corrosion resistance on unpainted deformed panels (perforating corrosion) was quantified by mass losses and pit depth measurements. Zinc‐coated boron steels were found to be more resistant to cosmetic corrosion than the other materials, and slightly more resistant to cut‐edge corrosion than the aluminized one. Red rust apparition could not be avoided due to the high iron content in all these hot‐stamped coatings. The three coated boron steels showed similar performances in terms of resistance to perforation. Aluminized boron steel presents the advantage of being less sensitive to hot‐stamping process deviation. Its robustness has been proved for many years on cars.     

一种Si-Mn系超高强度钢板的热冲压成形试验研究

 采用弯曲件热冲压成形试验研究了板料加热温度、保温时间及移送时间等工艺参数对一种Si-Mn系超高强度钢板热成形零件的力学性能及微观组织的影响规律。结果表明,通过控制热成形工艺参数,在所设计的模具上可实现Si-Mn系超高强度钢板热成形零件的有效淬火,在合适的工艺参数下,可获得细小均匀的马氏体组织,从而获得抗拉强度1700MPa以上,伸长率10%以上的性能,达到原始板料抗拉强度的3倍左右,并明显高于传统的Mn-B系超高强度钢板。     

温成形中锰钢的组织性能评价

 热成形零件已在汽车安全件上广泛应用，为了进一步提升零件碰撞安全性、提高表面质量、降低成本，基于中锰钢提出了一种降低加热温度的热成形技术，通过将完全奥氏体化的中锰钢在模具中淬火成马氏体组织获得超高强度力学性能，与22MnB5钢热成形相比，在获得1 500 MPa抗拉强度时，中锰钢温成形的加热温度可降低150 ℃以上，断后伸长率提高30%以上，同时提高零件的表面质量。综述并评价了中锰钢经温成形后的微观组织与力学性能以及冷弯性能、成形性能、电阻点焊等工艺性能，并与22MnB5钢热成形进行了系统地比较，体现出温成形中锰钢节能环保、提高碰撞安全性的技术优势。     

Improvement of Mechanical Properties of Automotive Components Using Hot Stamping With Integrated Q-P Process

Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping.Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength.This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process,which improves both strength and ductility of obtained structures at the same time.Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing.To test microstructure development,thin sheet was hot formed and a corresponding FEM simulation was created.This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn,Si and Cr.Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%.     

Determination of Thermal and Mechanical Material Properties of Ultra‐High Strength Steels for Hot Stamping

Direct and indirect hot stamping presently constitutes one of the most innovative forming technologies in the automotive industry through the combination of forming and hardening in one process step or line. Thus, structural components with strength up to 1600 MPa can be accomplished with the quench hardenable ultra‐high strength steel 22MnB5. With respect to the numerical investigation of the feasibility of different parts the knowledge of various thermal and mechanical material characteristics determined under process relevant conditions are required. Within the scope of this paper different experimental methods will be introduced for the determination of material properties according to the typical time‐temperature characteristics of the hot stamping process, as well as the modelling of it as input data for the FE analysis.