H13改进型热作模具钢的组织与性能

 研究了高锰型马氏体热作模具钢SDH3-Mod的室温冲击韧性、回火稳定性和热疲劳性能,并结合透射电镜(TEM)分析了锰对其微观组织的影响。结果表明：SDH3-Mod钢回火组织中残余奥氏体以薄膜状存在于马氏体板条间,提高冲击韧性,延缓裂纹扩展;同时,锰在高温时阻碍碳化物粗化长大和延迟基体的回复再结晶,提高抗回火软化能力和热疲劳性能,使SDH3-Mod性能优于H13。     

Inclusion Variations of Hot Working Die Steel H13 in Refining Process

 Inclusion variations of die steel H13, including changes of species, morphologies, compositions, amounts and sizes, in the production of EAF→LF→VD→ingot casting→electro-slag refining (ESR) procedure, were investigated by systematic sampling, and analyzed with scanning electron microscope (SEM), energy dispersive spectrum (EDS), and metallographic microscope. The variation mechanism was studied by comprehensive analysis of total oxygen, nitrogen, and acid soluble aluminum as well as chemical test of refining slag. Based on the investigations, technical measures for cleanness improvement were discussed. The results show that oxide inclusions in H13 steel change from irregular Al2O3→near globular CaO-MgO-Al2O3 and CaO-Al2O3-SiO2 complex inclusions→finer CaO-Al2O3-SiO2 inclusions with higher CaO content→CaO-Al2O3-SiO2 inclusions with higher Al2O3 content and irregular MgO-Al2O3 inclusions→fine irregular MgO-Al2O3-CaS inclusions in various steps of the production; the variations are related with changes of acid soluble aluminum content, reactions between slag and steel, re-oxidation of liquid steel during casting, and refining of ESR. It is also found that Al2O3 inclusions are modified by refining slag in LF and VD refining; and ESR plays a good role in inclusion removal, especially in controlling the large linear VC-CrC-MoC inclusions distributed in grain boundaries. It is suggested that casting protection should be improved, and the basicity of refining slag and acid soluble aluminum content in steel should be raised.     

美标H13热作模具钢的锻造工艺优化

莱钢开发了美标H13热作模具钢并对锻造工艺进行了优化,优化后的锻造工艺采用三火成形,加热温度1260℃,锻造过程合理控制砧宽比、料宽比等工艺参数,提高锻件中心压实效果,锻后快冷并采用合理的球化退火工艺抑制网状碳化物析出,组织均匀,锻件的各项技术指标均完全满足技术要求。     

Effects of Lanthanum on Mechanical Properties of 5CrNiMo Forging Die Steel

The alteration of the strength, hardness and impact ductility of 5CrNiMo steel using three different additions of RE La element is studied in this paper. The mechanical properties of 5CrNiMo steel with RE La additions are be compared with that of the 5CrNiMo steel on the same heat-treatment condition without RE La element addition. The results show that the strength. hardness and impact ductility of 5CrNiMo steel will be improved obviously when the content of RE La element is proper, and as the content of RE La element is 0.033% (mass fraction), the 5CrNiMo steel has the best mechanical properties.     

热作模具钢H13的非金属夹杂物研究

 通过对EAF－LF－VD－MC－ESR工艺生产模具钢H13各工艺环节系统取样,采用多种分析方法分析夹杂物的形貌、尺寸、数量及组成,系统研究了H13钢生产过程中夹杂物演变规律,同时对模具钢中TiN和VC夹杂物的析出进行了理论分析,并提出了生产过程中控制TiN和VC夹杂物析出的措施。     

影响H13热作模具钢等向性的因素

 通过显微组织和断口分析并与化学成分分析和力学性能测试相结合的方法,研究了H13钢铸态组织特征、碳化物类型和分布对等向性能的影响。结果表明：在冷却过程中,H13钢铸锭会产生严重的宏观元素偏析,在铸锭的个别区域,特别是最后凝固的中心区域,出现的少量不平衡亚稳定共晶碳化物、宏观偏析严重的铸态组织经变形而形成的带状组织、缓慢冷却形成的二次碳化物网是影响H13钢等向性的主要因素。     

Prediction and Analysis on Oxidation of H13 Hot Work Steel

The understanding of oxidation behaviors on H13 steel was helpful to improve the service life and performance of hot work moulds and dies. Thermal-Calc Software was performed to calculate the oxidation phases on H13 steel along with different partial oxygen pressures in the interesting temperature range of 500-700 ℃. In this range H13 steel samples were treated respectively in different atmosphere including flowing water vapor （0.2 MPa）, normal pressure air （0.1 MPa） and low pressure air （0. 001 MPa）. The different oxidation films were detected with optical microscopy and X-ray diffraction. The microstructures and phase constitutions of the films formed in low pressure air were similar to those of the films formed in water vapor, and obviously different to those of the films formed in normal pressure air. The oxidation mechanisms of H13 steel in different atmosphere were also discussed.     

热作模具钢热处理工艺及深冷处理研究

研究了X20CoCrWMo10-9热作模具钢在1 000～1 180℃淬火温度下的组织和性能,并确定材料的最佳淬火温度为1 120℃;经不同工艺深冷处理后对钢进行显微组织观察和力学性能测试。结果表明,深冷处理可以不同程度提高钢的硬度和耐磨性。对比不同回火温度与时间下的性能,制定该钢适宜的深冷处理工艺为:1 120℃淬火+深冷处理8 h+650℃×1 h回火。     

热作模具钢的硬韧性因子

 根据热作模具钢的服役条件,基于均匀设计试验方法,设计了6种不同成分的热作模具钢,同时设计了对应的热处理工艺。测定了这6种钢的室温冲击韧性和二次回火后的硬度,提出了硬韧性因子(HT),并利用二次型逐步回归分析方法得到了硬韧性因子与化学成分及热处理工艺之间的关系。     

喷射沉积H13钢的组织和硬度

用传统铸造和喷射成形工艺制备了H13钢,然后再进行锻造加工,利用光学金相显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析(XRD)等分析方法及硬度测试对不同工艺制备的H13钢的显微组织和硬度进行分析.研究结果表明,喷射成形及其锻造加工的H13钢的组织及硬度明显的优于传统工艺制备的H13钢.     

4Cr2WMoVSi热作模具钢的研究与应用

以多元少量的合金化原则设计的4Cr2WMoVSi钢是一种经济型热作模具钢,研究了4Cr2WMoVSi钢的热处理工艺及性能,并与3Cr2W8V钢的热处理工艺和性能作了对比,用4Cr2WMoVSi钢制作了热剪刃,进行了装机使用试验,其使用寿命与3Cr2WSV剪刃的寿命相当,而是5CrW2Si剪刃寿命的3．4倍。     

镧对5CrMnMo热作模具钢力学性能的影响

研究了La对5CrMnMo钢的强度、硬度、塑性和冲击韧性的影响,并在相同的热处理工艺条件下,分别加入3种不同含量La后与不添加La的5CrMnMo钢的力学性能进行对比。结果表明：La加入量在适当的范围内可显著提高5CrMnMo的强度、硬度、塑性和冲击韧性,并且当La加入量为0.25%（质量分数）时,5CrMnMo钢可获得最好的综合力学性能。     

莱钢LGP20CH预硬型模具钢的开发生产实践

通过合理的化学成分设计,采用转炉、LF、RH、连铸、控制轧制与预硬化热处理工艺,成功开发出LGP20CH模具用钢并批量生产。实物质量检验表明,钢板钢质纯净度高,主要为B类夹杂物,级别在1．5级以下,钢板组织为回火索氏体,晶粒度达到9级以上,100％超声波检验合格,无气孔、针眼缺陷;整张钢板硬度波动值不超过4HRC,完全满足用户使用要求。     

Calculation and Analysis of Valence Electron Structure of Mo2C and V4C3 in Hot Working Die Steel

Taking the hot working die steel （HWDS） 4Cr3Mo2NbVNi as an example, the phase electron structures （PES） and the biphase interface electron structures （BIES） of Mo2C and V4 C3 , which are two kinds of important carbides precipitated during tempering in steel were calculated, on the basis of the empirical electron theory of solids and molecules and the improved TFD theory. The influence of Mo2 C and V4 C3 on the mechanical properties of HWDS has been analyzed at electron structure level, and the fundamental reason that the characteristic of the PES and the BIES of carbides decides the behavior of them has been revealed.     

热处理温度对热镀锌双相钢组织和性能的影响

对不同温度热处理的两种热镀锌双相钢的组织和性能进行了测试,研究了热处理温度对热镀锌双相钢组织和性能的影响,结果表明:在780 ℃热处理时,组织中存在一定比例的珠光体组织,当热处理温度在800 ℃以上时,组织为铁素体 马氏体.热镀锌双相钢的屈服强度随热处理温度的升高而降低,当热处理温度从780 ℃上升到800 ℃时,屈服强度急剧下降.屈强比随热处理温度的升高而降低,当热处理温度从780 ℃上升到800 ℃时,屈强比急剧下降.     

Effect of Microstructures on Resistance of a Hot Elevated-Temperature Wear Working Die Steel

 Elevated-temperature wear tests under atmospheric conditions at 400 ℃ were performed for a hot working die steel H21 on a pin-on-disk wear tester. The phase and morphology of worn surfaces were examined using XRD and SEM, and the relation of wear resistance to tempered microstructures was studied for H21 steel. XRD patterns exhibit that oxidative wear is a predominated wear mechanism with Fe3O4 and Fe2O3 on worn surfaces. It is found that with increasing normal load, obvious plastic deformation of substrate appears on worn surfaces. Microstructures start to affect apparently wear resistance of the steel with an increase of load. Under loads of 50-100 N, wear losses of steel retain low values and relatively approach for steels with various microstructures. As loads are increased to 150-200 N, wear losses of steel start to increase obviously and present apparent difference for steel with various microstructures. Wear resistance is found to increase in the sequence as follows: tempered sorbite, tempered martensite, tempered troostite without secondary hardening and tempered troostite with secondary hardening or upcoming one. Higher strength and microstructural stability are required for steels with excellent wear resistance.     

稀土钇对奥氏体耐热钢高温拉伸性能影响及作用机制

研究了钇对奥氏体耐热钢21Cr-11Ni-1.5Si-N的高温拉伸性能的影响及相关机制.在750～1200℃,应变速率为0.005S-1条件下进行了含与不含钇试样的热拉伸模拟试验及组织分析.结果表明:钇通过细化晶粒、强化晶界提高了试验钢在750～850℃的热塑性和抗拉强度;由于钇抑制了动态再结晶和再结晶晶粒长大,使得在...     

Effect of Niobium on Microstructure of Cast AISI H13 Hot Work Tool Steel

The effect of niobium addition on the microstructure of cast AISI H13 hot work tool steel was evaluated by using EDX analyzer attached to the scanning electron microscope. The volume percent of eutectic area and eutectic cell size and also volume percent of different carbides of new steel, which is heat treated under different conditions, are also determined. The results show that the a niobium addition modifies the cast structure of Nb-alloyed hot work tool steel, and reduces the size and volume of eutectic cells, and increases the maximum hardness of the steel.