高浓度碳氮共渗在高速钢冷挤压模上的应用研究

本文主要对18Cr4V钢高浓度碳氮共渗后的渗层成份、显微组织、硬度分布、共渗时间对渗层深度的影响以及实际使用效果等进行了研究分析。结果表明,W18Cr4V钢制黑色金属冷挤压摸经高浓度碳氮共举直接淬火 低温回火后,可显著提高其表面硬度、耐磨性和抗咬合性能,使用寿命较常规热处理可提高4～5倍。     

硬质合金热处理研究进展

综述了硬质合金热处理研究进展,普通硬质合金可通过淬火回火处理,渗硼碳及硼－镧共渗化学热处理,双重淬火回火处理,真空热处理,离子注入,激光热处理来提高其抗弯强度,表面硬度和耐磨性,断裂韧性等力学性能,钢结硬质合金可通过选择合适的淬火回火工艺,渗硼和硼－硫共渗化学热处理来提高合金的表面硬度,耐磨性和热疲劳抗力,从而达到提高硬质合金产品使用寿命的目的。     

3Cr2W8V钢制模具的热处理与强化方法及应用

综述了3Cr2W8V钢制模具的热处理研究方法及应用实例。3Cr2W8V钢可采用淬火、回火处理，渗碳、渗氮、渗硼及碳氮共渗、渗铝、渗铬及铬—铝—硅三元共渗等化学热处理，镀金属等表面强化处理来提高其高温强度、冷热疲劳抗力、耐磨性、抗腐蚀性及防粘模等性能，从而达到提高3Cr2W8V钢制模具的使用寿命的目的。     

4Cr5MoSiV1（H13）钢的气体氮碳共渗

为提高热作模具钢4CrSMoSiV1钢的耐磨性和热疲劳性能,对其进行氮碳共渗处理。试验表明,对于4Cr5MoSiV1钢,采用NH3和CO2作渗剂进行氮碳共渗,产品的质量比采用其他氮碳共渗工艺处理的更稳定,渗层表面硬度与气体渗氮层相接近。     

20Cr3MoWVA钢热处理工艺研究

对20Cr3MoWVA合金钢齿轮进行不同工艺的热处理,并对热处理后的金相组织、表面硬度和心部硬度进行检测分析。结果表明,20Cr3MoWVA钢齿轮经碳氮共渗或渗碳后,重新加热到910℃快速油淬,经冰冷处理+低温回火后,其性能可满足技术要求。     

表面改性技术对38CrMoAl钢组织与性能的影响

对38CrMoAl钢进行碳氮共渗、氮碳共渗和脉冲真空渗氮处理,研究了表面改性后钢的显微组织、表面相结构、硬度、耐磨性和耐腐蚀性能。结果表明,碳氮共渗试样表面组织为回火马氏体;氮碳共渗试样表面组织为Fe24N10化合物;脉冲真空渗氮试样表面组织为Fe2-3N化合物。脉冲真空渗氮试样的表面硬度最高(1 026 HV),磨损量最少;氮碳共渗试样的耐腐蚀性能最好,其锈蚀等级为4级。     

塑料模具钢及真空碳氮共渗热处理

介绍了常用的塑料模具钢及其相应的热处理工艺,并试验了碳素钢及P20(3Cr2Mo)钢制塑料模具的真空碳氮共渗工艺.结果表明碳素钢及P20钢制塑料模具经真空碳氮共渗油淬火处理后,淬火硬度值可提高至62 HRC以上,耐磨性增加,有助于提高模具的使用寿命.     

18Cr2Ni4WA钢真空碳氮共渗工艺试验

制定了一种18Cr2Ni4WA钢的真空碳氮共渗的热处理工艺,研究了该真空碳氮共渗工艺对18Cr2Ni4WA钢的微观组织和性能的影响。结果表明,18Cr2Ni4WA钢经真空碳氮共渗、高压气体淬火、深冷与低温回火后,表层微观组织为细针状马氏体,心部为板条状回火马氏体;表面残留奥氏体含量为9.19%(Vol.);试样表面硬度达到了901 HV0.2,有效渗碳层深度达到了1.3 mm。     

H13模具钢低温盐浴氮碳钒共渗工艺研究

探讨了H13模具钢的低温盐浴氮碳钒共渗工艺,并对渗层组织、硬度、渗层中的元素分布以及物相组成等进行了研究。结果表明:低温盐浴氮碳钒共渗工艺明显提高了H13模具钢的显微硬度,并且渗层中的物相有利于提高模具的热疲劳性能和耐磨性,采用该工艺处理H13热作模具,使用寿命有了明显改善。     

碳氮共渗热处理工艺对42CrMo钢组织性能的影响

对42CrMo销轴进行表面改性处理,研究了碳氮共渗热处理工艺下材料显微组织和力学性能的演变规律。结果表明,42CrMo钢经碳氮共渗改性处理后,表面显微组织为碳氮共渗硬化层,芯部组织为低温回火混合马氏体和片条状铁素体;材料在不损失芯部塑韧性的同时,表面硬度得到大幅提高。经200℃低温回火后,42CrMo钢抗拉强度基本保持不变,芯部冲击韧度约提高了7.7%,表面硬度高达650 HV。     

TiC弥散强化2Cr13钢的显微组织及耐磨性

运用原位合成工艺可以制备出含量为3%的微米级TiC颗粒弥散强化2Cr13不锈钢,TiC颗粒在强化钢中分布均匀,与基体结合良好。TiC颗粒的加入,使2Cr13不锈钢的室温强度提高10%左右,硬度小幅增加,但塑性有所降低。用环-块摩擦磨损试验机研究了油润滑下弥散强化钢的滑动摩擦磨损性能,发现TiC颗粒承受载荷,从而可有效地提高弥散强化钢的耐磨性。与未增强的2Cr13基体相比,弥散强化钢的摩擦系数平稳且较低,而耐磨性提高3倍以上。     

Effect of TiC particles on the oxidation behavior of 2Cr13 stainless steel in a simulated marine environment at 550°C

In this study, the oxidation behavior of 2Cr13 stainless steels with/without TiC particles was investigated in a simulated marine environment at 550°C. The results showed that TiC particles greatly accelerated the oxidation rate of 2Cr13 steel during the cyclic oxidation reaction. At the same time, the effect of acceleration was alleviated by the small size and uniform distribution of TiC particles. As galvanic corrosion in the vicinity of TiC particles occurred in 3.5% NaCl solution spray, more NaCl particles deposited on the alloy surface, especially in the area around TiC particles. At 550°C, some shell-like oxidation products were generated on the 2Cr13 steel surface due to TiC addition, and then the porous oxidation products provided poor protective ability. Besides, the defect and stress in the oxide scale was reduced due to the small size and uniform distribution of TiC particles in 2Cr13 steel.     

电渣重熔对TiC强化2Cr13不锈钢力学性能和断口的影响

在2Cr13不锈钢中引入TiC颗粒后,室温强度有大幅提高,但塑性和冲击韧性却发生了较大幅度的下降．原位合成的TiC颗粒,尺寸较大且有轻微团聚现象,导致了在拉伸和冲击过程中颗粒易破碎,断裂机制是以TiC增强体失效为主;对TiC强化2Cr13进行电渣重熔后,综合性能得到了改善,TiC颗粒变小且分布变均匀,在拉伸和冲击过程中颗粒不易破碎,断裂机制是以TiC与基体的界面失效为主．     

电火花沉积Ni/Ti(C,N)金属陶瓷复合涂层的组织及性能研究

目的提高H13模具钢的表面耐磨性,探索金属陶瓷涂层的应用。方法分别用Ti(C,N)基金属陶瓷棒和纯镍棒作为电极,氩气为保护气体,在H13钢表面电火花沉积制备Ni/Ti(C,N)金属陶瓷复合涂层。使用X射线衍射仪对涂层的相组成进行了分析,并用扫描电子显微镜及能谱仪观察涂层的微观结构和元素分布情况,采用显微硬度计和CSM球盘式摩擦计对涂层的显微硬度和不同载荷下的耐磨性进行测试。结果涂层表面为单脉冲沉积斑点堆积而成的溅射状形貌,Fe和Ti元素整体上呈现出分区富集的特征,强化层主要物相包括TiC(0.7)N(0.3)、Ni(17)W3、Ni-Cr-Co-Mo和Fe3Ni2。涂层截面组织均匀,缺陷较少,厚度约为31μm,Fe、Ti和Ni元素均在界面处发生扩散,形成了良好的冶金结合,过渡层与基体相互混合,呈现出机械式的咬合结构。涂层的显微硬度实测最高值达1420HV,约为基体的5.4倍。涂层具有比基体更低的摩擦系数,且30 min内的磨损质量损失仅为基体的1/2,涂层磨损机理主要为粘着磨损和轻微的磨粒磨损。结论在H13钢表面电火花沉积制备的Ni/Ti(C,N)金属陶瓷复合涂层可提高其表面的硬度、耐磨性,且具有一定减摩性,可以起到延长模具寿命的作用。     

TiC系耐热钢结硬质合金研究

研究了以 Ti C为硬质相 ,相当于热作模具钢 (H 13)为粘结相的耐热钢结硬质合金。测试了在不同淬火温度下和高温回火状态下的硬度和部分机械性能及显微组织。证明该合金有进一步研究和实际应用的价值。     

高Ti低合金钢中TiC粒子的固溶及沉淀析出行为

通过高温激光扫描共聚焦显微镜(Laser scanning confocal microscopy,LSCM)观察高Ti(0.6wt%Ti)低合金钢升温和降温过程中TiC粒子的演变规律,结合Thermo-Calc软件计算并借助OM、SEM、TEM等分析方法对试验钢中TiC粒子形貌和分布进行表征,研究TiC粒子的析出规律。试验结果表明:不同温度阶段生成的TiC粒子形态各异,按照粒径由大到小顺序逐渐从基体中析出,高温对小尺寸TiC粒子析出的抑制作用更为显著。高温下多个尺寸较大的相邻TiC粒子会在试样表面发生聚集形成絮状形貌,高温固相析出的TiC粒子由球体不稳定状态向立方体稳定形貌转变,粗化程度可忽略。     

Synthesis and Evaluation of TiC/Al3Ti Coating on Iron Via Thermal Explosion of Al-Ti-C System

Thermal explosion reactions of Al-Ti-C system were studied. It was found that TiC and Al₃Ti could be synthesized as final products in the Al-Ti-C system. A particular morphology variation of TiC occurred with an increase of TiC content. TiC presented a strip form as the content of TiC was 20 wt.%; with an increase of TiC, its shape changed to a granular form with a reduced size. A TiC-reinforced Al₃Ti intermetallic matrix composite coating was successfully fabricated on an iron substrate by the thermal explosion of Al-Ti-C system during casting. As the contents of TiC reached 20-40 wt.%, the reactions of Al-Ti-C system were ignited and fully completed by molten iron to achieve a compacted coating with a good metallurgical bonding between the coating and basal iron. The elements of Al, Ti, C, and Fe gradiently distributed from the coating to the matrix. The hardness of the coating was substantially higher than that of the matrix and slightly increased with an increase of TiC content. The composite coating presented relatively lower wear rates than H13 steel at 25-400 °C.     

Fabrication of cast carbon steel with ultrafine TiC particles

The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.     

激光熔覆原位合成陶瓷相增强铁基熔覆层的组织和性能

利用6 kW光纤激光器在Cr12MoV汽车模具钢表面激光熔覆含有Ti-Fe,B₄C粉末的铁基合金粉,在汽车模具钢表面直接原位合成TiC+TiB₂颗粒增强的铁基合金复合涂层.涂层与基体呈良好的冶金结合,涂层组织细小,结构致密,宏观质量较好. XRD分析结果表明,涂层组织由α-Fe,TiC,TiB₂组成. TiC,TiB₂相均匀分布于熔覆层中.由于TiC,TiB₂硬质相的形成以及激光的快速凝固冷却获得的细晶组织,使得熔覆层的显微维氏硬度有了明显提高.在距离熔覆层表面1.2 mm处显微维氏硬度高达1000 HV,有利于促进熔覆层耐磨性的提高.     

Characterization of in situ synthesized TiC particle reinforced Fe-based composite coatings produced by multi-pass overlapping GTAW melting process

In this paper, in situ synthesized TiC particles reinforced Fe-based surface composite coatings by multi-pass overlapping gas tungsten arc welding (GTAW) melting process employing a proper amount of graphite and ferrotitanium (FeTi) on AISI 1020 steel substrate was produced. The microstructure and wear properties of the composite coatings were investigated by means of an electron microprobe microanalysis (EPMA), X-ray diffractometer and wear tester. The results showed that the multi-pass overlapping GTAW melting surface composite coatings can be obtained under suitable welding parameters, and no crack and porosity are found in the tracks. The X-ray and EPMA results confirm that TiC particles can be formed via reaction of FeTi and graphite during multi-pass overlapping GTAW melting process. TiC particles present cubic and dendrite shape in the non-overlapping zone. It is found that there occurred TiC particles coarsening at the overlap regions, which can lead to detrimental effects on the hardness and wear performance. Composite coatings give a high hardness and excellent wear resistance; and the wear friction coefficient of the coating is less than that of the 1020 steel. As a result, multi-pass overlapping GTAW melting process can be used effectively for producing surface composite coatings with a pre-placed powder to improve wear resistance of the AISI 1020 steel.