模具材料在冲击载荷下磨损性能的评价与研究

以往对模具钢耐磨性的评价,大都采用摩擦偶件稳定接触的磨损试验方法。这种试验方法对模具钢的服役条件模拟性差。本文利用动载磨损试验机,对W18Cr4V和Cr12MoV钢在不同工艺条件下的抗冲击磨损特性进行了研究,并与高速钢制冷镦模具的实际应用效果进行了对比,发现实验室数据与现场应用效果吻合较好。同时结合磨损形貌的显微分析,对模具钢冲击磨损机理进行了初步探讨。     

模具材料的高温滑动冲击磨损过程的电镜观察

在模拟热作模具热磨损试验机上进行高温滑动冲击磨损试验,在各磨损阶段,用扫描电镜对模具试样表面形貌作细致观察,得出如下结论:高温滑动冲击磨损过程的主导磨损机制,早期为磨粒磨损,中期及后期逐步向点状剥落及大块疲劳剥落转移。全部过程都有粘着磨损,后期更为严重。     

钢的高温性能和模具的失效分析

本文简要介绍了新型热作模具钢(HD)的高温性能,这种钢的高温强度和热疲劳热磨损抗力优于3Cr2W8V钢,对其原因进行了适当的分析。同时,对铜管热挤压底模进行了失效分析和硬度检验、表层组织分析以及热疲劳热磨损形貌观察,结果表明模具的变形和拉毛失效均与模具材料的高温强度、组织稳定性以及均匀性密切相关,从而说明了HD钢模具使用寿命高的机制。     

高温塑性变形摩擦磨损试验方法的研究

为适应热作模具的高温塑性变形摩擦磨损的研究和为热作模具选材提供依据,建立了高温塑性变形摩擦磨损试验方法。对热作模具钢5CrMnMo,4Cr5MoV1Si和3Cr2W8V的高温塑变抗磨性能进行了评定,同时用环型试验测定了在无润滑和水剂石墨润滑条件下的高温塑性变形摩擦系数。高温塑变抗磨性能评定结果与 Thomas,Dennis等人所测定的结果较好地吻合,同时还与汽车配件七厂的热锻模寿命试验结果较接近。借助于扫描电镜对磨损表面的形貌分析,对5CrMnMo,4Cr5MoV1Si,3Cr2TW8V的高温塑变抗磨性能进行了初步讨论。     

铝合金挤压模具的失效与热磨损热疲劳性能

根据铝合金挤压模具的服役条件及其对材料的要求,分析现场模具的失效形式和验证所采取的提高寿命的措施。对3Cr2W8V钢和炉外真空精炼(VHWD)4Cr5MoV1Si钢进行了全面性能与生产对比试验证明:4Cr5MoV1Si钢用于制作铝合金挤压模是较理想的材料,能够显著提高模具的寿命。通过热磨损、热疲劳试验,比较两种材料的热磨损抗力和热疲劳的抗力;并观察其微观表面形貌。     

磨损条件对冷作模具钢的磨粒磨损特性及机理的影响

本文通过对三种冷作模具钢LDI、65Nb和Cr12MoV在不同磨损条件下的磨粒磨损试验,并结合金相组织分析和SEM形貌观察,研究了试验钢的磨粒磨损特性,讨论了钢的组织和力学性能对耐磨性的影响。结果表明:材料的磨损机理随磨损条件的变化而变化;LDI钢540℃两次回火组织具有优良的耐磨性。     

基于正交试验法的模锻模具磨损分析及优化

模具磨损是模锻成型过程中模具的主要失效形式,因此如何减小模具磨损量,进一步提高模具的使用寿命,是模锻工艺中急需优化的关键性问题。提出一种模锻成型过程中基于模具磨损的工艺参数优化方法,属于模锻工艺领域,是一种将模锻加工过程中的有限元模拟仿真试验与正交试验设计相结合的工艺参数优化方法。以热模锻工艺为例,在Archard磨损模型的基础上,推导出适用于热模锻模具磨损分析的修正模型,并且对热模锻中模具磨损过程进行基于Deform软件的有限元仿真分析。研究热模锻加工过程中模具工作表面的磨损深度与模锻工艺参数之间的关系,利用正交试验设计将不同的工艺参数进行组合分析,通过较少的仿真试验次数得到适用于热模锻的最优化工艺参数。使用极差分析法进行试验数据处理,推导出对模具磨损影响程度最大的工艺参数,为热模锻工艺中的模具磨损问题提供一种基于正交试验设计的工艺参数优化方法,得到模锻成型过程中使模具磨损量实现最小值的工艺参数最优解。     

分体镐靴磨损性能研究

探讨了镐靴用工模具钢材料的热处理工艺,并测试了其冲击磨损性能及相关性能,观察分析了冲击磨损断口形貌及各特征区形貌.结果表明：所选镐靴用钢热处理硬度和显微组织都达到预期的目标,分体镐靴技术可行.磨损表面由冲击磨损区与滑动磨损区组成,磨损以凿削式磨损为主,基本无大块脆性剥落及疲劳痕迹.     

WCML-2热作模具钢的研究

为了提高铝型材挤压模具的使用寿命在H13钢的基础上加入3％WC,用电冶特殊方法获得新材料──WC热作模具钢通过硬度弯曲冲击耐磨性等试验以及通过金相电镜能谱分析得出该材料在1050℃和600℃处理后具有最佳综合力学性能寿命由1．5～2t提高5～7t．     

模具材料优化选择与系统工程

以系统工程的观点对模具材料优化选择的决策进行了初步的探讨 ,并从抓主要矛盾解决问题的方法 ,就热作模具材料的优化选择提出了三类主要的决策方法 :绝大多数热作模具在高温重载下工作 ,模具寿命短 ,甚至一个工班要换几个模具 ,因此用失效抗力性能高的热作模具钢来制造此类模具 ;对锌、铅、锡等低熔点合金的压铸模或热挤压模 ,一般在 4 5 0℃下工作 ,服役条件相对好 ,可按产品批量大小选择 ,例如几十万件的可选合金结构钢 4 0Cr,30CrMnSi等 ,若批量上百万件的便选用标准热作模具钢 5CrNiMo ,H13,3Cr2W8V等 ;热冲裁模工作温度一般在 30 0℃以下 ,所有的热作模具钢都合用 ,因此着重从便于生产管理出发来选所用的钢材 .     

3Cr2W8V钢高温磨损表面扫描电镜分析

作者用扫描电子显微镜,电子探针等分析了3Cr2W8V钢高温磨损表面,考察了磨损表面形态随试验温度及试验时间的变化规律,给出了相应的磨损表面特征照片,并结合磨损机理分析了该钢的温度——磨损特性曲线。文中还着重分析了高温磨损时在表面形成的“形成层”的成分、作用及形态,并探讨了磨损表面上沟槽产生的原因。     

激光处理非光滑凸包表面的耐磨性试验

采用试验优化技术中的均匀设计方法进行了影响凸包非光滑表面耐磨性的多因素复杂试验。通过用统计分析软件SPSS(StatisticalPackagefortheSocialScience)处理试验数据 ,得出了激光处理仿生非光滑凸包表面耐磨的多因素回归方程。试验证明 ,速度、负荷、时间和凸包圆周方向的距离对耐磨性有显著影响 ,凸包轴向的距离对耐磨性影响不大。     

Fretting wear of steel wires in hoisting ropes

To investigate the fretting wear of steel wires in hoisting ropes, specimens were made of 6 × 19 point contact ropes. A model for the fretting wear was developed and a fretting wear test rig was designed in laboratory. A series of experiments were performed on this test rig. The wear volume was taken as a characteristic parameter to describe the fretting wear in relation to the contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussed in the fretting process.     

燃煤发电厂省煤器管高温冲蚀磨损特性的研究

利用自制高温冲蚀磨损试验装置,对燃煤发电厂省煤器管道(20钢)进行高温冲蚀模拟试验,并对20钢室温冲蚀以及Ni-W合金刷镀层高温冲蚀作了对比试验。结果表明,局部塑性变形、疲劳剥落、犁削和切削作用是20钢管道高温冲蚀磨损的主要机理。Ni-W合金刷镀层脆性大,结合力不强,不能提高省煤器管道的使用寿命。     

Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.     

High Temperature Wear Characteristics of a New Hot Work Die Steel CH95

High temperature wear characteristics of a new hot work die steel CH95 doped with a small amount of rare earth （ Re ） and boron （ B ） have been investigated and compared with those of conventional die steel H11 at a series of temperatures and loads. Worn surfaces of CH95 steel and H11 steel were analyzed with a scanning electron microscope. It is found that high temperature mechanical properties of CH95 steel are much better than those of H11 steel. The oxide layer formed on the worn surface plays an important role in wear resistance at high temperature. When the load is less than 63 N, the surface oxide layer keeps integrated and the effect of load on high temperature wear is small. When the load is higher than 63 N, the supporting ability of matrix to the oxide layer decreases with the increase of load, which results in an increase of wear rate. Compared with H11 steel, the wear resistance of CH95 steel is much better and the worn surface of CH95 steel is smoother. It is easier for CH95 steel to form a compact and integrated surface oxide layer at high temperature than for Hll steel, which protects the worn surface and reduces wear.     

模具钢Cr12MoV精密硬态切削过程刀具磨损

模具钢Cr12Mo V硬态切削过程中,工件材料的高硬度导致了刀具在切削过程中受到剧烈的热力耦合作用,刀具的磨损机制也明显不同于常规的切削过程.本研究以PCBN刀具精密硬态切削模具钢Cr12Mo V过程为对象,分析了刀具前刀面和后刀面的磨损规律,通过元素变化分析得到刀具不同位置的磨损机制;通过揭示不同切削速度和进给量下的刀具磨损规律为合理选择切削参数提供理论依据;研究揭示了切削合力和切削三分力受刀具磨损量的影响机制;通过建立磨损刀具的几何模型,采用有限元仿真软件Deform对不同刀具磨损量下的切削过程进行了仿真分析,得到了刀具磨损对切削温度场的影响机制.     

Friction and wear mechanism of unlubricated 304L austenitic stainless steel at room temperature

To explore wear mechanism of stainless steel used in nuclear pump,the wear properties and the worn surface characteristics of unlubricated 304L austenitic stainless steel on itself were investigated in air at room temperature.The experimental results demonstrated that the wear rate of the material decreased with the increase of the wear time.The friction coefficient fluctuated severely when the applied load was 120 N.At 120 N the wear rate was much higher than that of the applied load of 70 N.At 70 N the wear rate did not show much difference from that of 30 N.The wear mechanism was adhesive and abrasive wear under different load at the initial stage of the wear test.Then,the main wear mechanism changed with the wearing time and the applied load.