带底深孔空心件热成形工艺改进分析

目的研究带底深孔空心件热成形工艺现状与改进措施。方法介绍分析了目前国内外所采用的新工艺、模具结构,新型润滑剂、强制润滑方法,新型模具材料、制造工艺及应用情况。结果采用压型、预冲孔、冲孔、拔伸工艺及模口导向的效果良好,通过高压将润滑剂从冲头内部流向冲孔冲头前端,可实现冲孔强制润滑,模具材料可用3Cr3Mo3VNb,4Cr2MoVNi,3Cr3Mo3W2V等,并采用表面强化等工艺。结论应用表明,上述改进措施可降低壁厚差,改进产品质量,并减小摩擦,降低成形力,比传统材料及工艺显著提高了模具寿命。最后指出了还需进一步解决的问题。     

提高热拔伸冲头寿命的研究

对35CrMnSi 钢制热拔伸冲头进行失效分析表明,冲头的失效形式是侧壁纵向开裂,引起冲头开裂的驱动力主要是热应力和组织应力,直接起因是冷热疲劳。针对失效原因优选出具有较高冷热疲劳抗力,断裂韧性和耐擦伤能力的模具材料,制定出合理的热处理工艺加以配合,基本上消除开裂,使冲头寿命提高2.5倍     

超高强韧性热模钢3Cr3Mo3VNb性能及其生产应用

将3Cr3Mo3VNb钢与H13、3Cr2W8V等热模钢的高温力学性能进行了比较,列举了它们在生产中的应用实例.结果表明,3Cr3Mo3VNb钢性能优于其它钢种;也论述了超高强韧性热模钢模块生产制作过程的质量保障措施.     

提高3Cr2W8V钢热挤压模寿命的工艺措施

从模坯锻造及预处理、热处理、机加工、电加工、表面强化和模具使用等方面,叙述了提高3Cr2W8V钢热挤压模寿命的工艺措施.生产实践证明,充分发挥工艺的潜力,可以大幅度提高模具寿命.     

摆线液压马达内花键输出轴冷锻成形工艺与模具研究

目的 为了提高摆线液压马达内花键输出轴零件的加工效率及材料利用率、降低生产成本,提出一种冷精密成形的工艺与模具。方法 首先分析了摆线液压马达内花键输出轴的形状特点,初步制定了三工序冷挤压成形工艺:正挤细杆—反挤深孔—反挤花键孔,并通过数值模拟和实物实验对该成形工艺进行分析验证。在工艺实验中发现,采用线切割方法加工的第3序通体花键形状冲头,在与冲头套下端面交界处极易发生断裂。因此对花键冲头的结构和加工方法进行了调整,将冲头整体设计为圆柱台阶状,头部采用电火花加工方法加工一段花键形状,花键与圆柱部分采用锥角过渡。结果 实验结果显示,锻件成形工艺稳定,成形锻件精度较高,改进后的冲头寿命较高。结论 内花键输出轴成形工艺可行,改进的冲头结构降低了冲头产生应力集中的风险,提高了抵御偏载力的能力,成形工艺与模具满足了批量生产的考核。     

超高强度钢DP1000液压成形A柱的关键技术

目的研究超高强度钢DP1000液压成形A柱仿真技术和试验效果,解决批量生产中DP100焊管技术和同步冲孔等关键技术。方法基于Autoform有限元模拟软件,仿真分析了DP1000液压成形A柱的可行性,试验了DP1000液压成形A柱零件。通过对比高频焊管和激光焊管的液压成形零件焊缝质量,解决量产零件开裂问题,开展了DP1000液压成形A柱的Cr12MoV、ASP30和SKH51不同材料的同步冲孔效果,解决DP1000材料冲头寿命和冲孔质量问题。结果采用DP1000材料可以获得液压成形A柱,具有制造可行性。与高频焊管相比,具有较小的热影响区和硬度变化较小的激光焊管,更适合DP1000液压成形A柱使用。结论 ASP30和SKH51比传统的Cr12MoV更适合于DP1000材料液压成形A柱同步冲孔,冲头寿命提高80多倍,冲孔质量良好。     

冲头断裂分析

冲头在热处理后放置时突然断裂,采用宏观断口、化学分析和金相检验等方法对其进行了分析.结果表明,冲头材料中存在显微疏松和热处理工艺不正确是引起断裂的主要原因.     

中华人民共和国机械行业标准热作模具钢显微组织评级(续)

图 6 - 1　 1级图 6 - 3　 3级图 6 - 5　 5级图 6 - 2　 2级图 6 - 4　 4级图 6 - 6　 6级图 6　 4Cr3Mo2 Ni VNb B钢马氏体评级图　 5 0 0×6　检验报告检验报告应包括下列内容 :a)试样或模具名称、图号、材料成分或钢号、热处理工艺及炉批号 ;b)检验数量及部位 ;c)检验结果 ,所附照片应注明放大倍数和侵蚀剂 ;d)检验日期及检验者。附　录　A4Cr3Mo2 Ni VNb B钢的有关参数(提示的附录 )A1　化学成分化学成分见表 A1。表 A1　化学成分 (w /% )C Cr Mo Ni V Nb0 .39～0 .422 .6 0～2 .802 .0 5～2 .2 00 .95～1.0 51.2 0～1.2 80 .…     

热穿孔冲头的设计

通过对热穿孔冲头的材料的选择、结构的设计可以大大提高该模具的使用寿命。     

冲头形状对液压冲孔塌陷的影响

为了研究管材液压冲孔中冲头形状对塌陷的影响规律,采用7种不同形状的冲头进行了液压冲孔实验,分析了冲头形状对液压冲孔质量的影响.实验结果表明:塌陷深度随着冲头端面倾斜角度的增大而减小,随着冲头圆角的增大而增大.提高内压能够降低塌陷深度,塌陷深度随着管内压力的增大而减小.不同形状冲头对塌陷的影响不同,斜冲头冲孔后塌陷较小,圆角冲头冲孔后塌陷较大.     

Shear Band Evolution in Polymer Bonded Explosives Subjected to Punch Loading

The shear band development and potential hot‐spot initiation of polymer‐bonded explosive were investigated under low‐rate punch loading and combined punch and thermal loading. The digital image correlation method was used for deformation analysis. The obtained results showed that the initiation and development of shear bands at room temperature occur in three stages and demonstrated that the material suffers a prolonged shear stress concentration in a local area. Large shear was shown to lead to the formation of slip bands in the hard‐phase area, indicating that this region has the highest potential to initiate hot‐spots even under low‐rate punching. For high temperatures, the initiation and development of shear bands occur in two stages, with the resulting flow field being close to Hill's solution except for a small area directly underneath the punch. Large plastic flow rate was shown to be another important feature besides shear banding.     

3Cr2W8V钢形变热处理研究

3Cr2W8V钢广泛应用于有色金属热锻、热挤压和压铸成形.为进一步挖掘3Cr2W8V钢的使用潜力,提高模具材料综合使用性能和使用寿命,本文开展了针对该钢的形变热处理研究,讨论了形变温度、冷却方式及回火温度对试样组织与性能的影响.研究表明高温形变热处理不适宜于3Cr2W8V,形变后水冷优于空冷,并得出组织性能俱佳的优化形...     

Creep rupture behaviour of circumferentially welded mod. 9Cr–1Mo steel pipe subject to internal pressure and axial load

The multi-axial creep strength of circumferential welds in power piping, including failure mode and failure life against a wide range of stress ratios and stress levels, was newly examined in this paper. The creep rupture behaviour of modified 9Cr–1Mo steel (9Cr–1Mo–VNb steel; ASME P91) pipe with a circumferential weld subject to combined internal pressure and axial load was experimentally investigated at 650 °C. The test results, with several kinds of stress ratios of macroscopic axial and hoop stress can be summarised as follows. Along with the increased stress ratio (axial/hoop), both failure location and failure mode changed from a base metal failure caused by hoop stress to an FGHAZ (fine-grained heat affected zone) failure due to axial stress. The stress ratio where the failure mode changed was ‘0.8’. Strength reduction in FGHAZ failure by axial stress should be considered in the structural design of circumferential welds. A series of FEM creep analysis was carried out to discuss the relation of the failure mode to both the local stress distribution and the damage. The failure mode variation along with the increase in the stress ratio is also discussed based on simplified ductile creep failure analysis.     

热处理工艺对1Cr15Ni4Mo3N钢组织和性能的影响

通过力学性能测试和显微组织观察,研究了热处理工艺对1Cr15Ni4M03N钢显微组织和力学性能的影响。结果表明：该钢经780℃×5h空冷和590℃×4h空冷二级退火处理后具有良好的切削性能,适合进行机加工;再经过1070℃×1h油淬、-70℃冷处理和200-470℃回火处理后,可获得较好的综合力学性能。     

Assessment of creep rupture properties for dissimilar steels welded joints between T92 and HR3C

Dissimilar steels welded joints, between ferritic steel and austenitic stainless steel, are always encountered in high‐temperature components in power plants. As two new grade ferritic steel and austenitic stainless steel, T92 (9Cr0.5Mo2WVNb) and HR3C (TP310HCbN), exhibit superior heat strength at elevated temperatures and are increasingly applied in ultra‐supercritical (USC) plants around the world, a complete assessment of the properties for T92/HR3C dissimilar steels welded joints is urgently required. In this paper, metallographic microstructures across the joint were inspected by optical microscope. Particularly, the creep rupture test was conducted on joints under different load stresses at 625 °C to analyse creep strength and predict their service lives, while their fractograph were observed under scanning electron microscope. Additionally, finite element method was employed to investigate residual stress distribution of joints. Results showed that the joints were qualified under USC conditions, and T92 base material was commonly the weakest part of them.     

Cr5Mo铸钢的碳含量与组织和性能的关系

研究了Ｃｒ５Ｍｏ 铸钢的碳含量与组织和性能之间的关系。依据试验结果,对照ＳＹＢ１５１０２－ ６３标准对性能的要求,详细探讨了碳含量以及热处理工艺对Ｃｒ５Ｍｏ 铸钢组织和性能影响的规律,给出了合理的碳含量范围和热处理工艺。