H13热作模具钢的表面热处理

H13(4Cr5MoSiV1)钢成分 (% )为 0 32～ 0 4 5C ,0 80～ 1 2Si,0 2 0～ 0 5 0Mn ,4 75～ 5 5 0Cr,1 10～1 75Mo ,0 80～ 1 2 0V是目前广泛用于热挤压模和压铸模的热作模具钢 ,工作温度达 6 0 0℃。介绍了离子渗氮、N C共渗、N C V共渗、O S N共渗、S N C共渗、多元共渗等提高H13钢抗热疲劳、耐热磨损和耐蚀性能的表面低温化学热处理工艺 ,以及激光表面处理、高能束表面合金化、离子注入表面改性处理等高能束流表面处理及其最新进展。     

薄板坯连铸连轧低合金耐磨钢磨料磨损特性

 研制了30CrMo,50CrV4两种牌号的薄板坯连铸连轧低合金耐磨钢板,对试验钢板进行淬火和低温回火热处理,并且与传统热轧工艺生产的热轧态的45,16Mn,Q235钢对比进行低应力磨料磨损试验,研究其磨损特性。结果表明,淬火低温回火态薄板坯连铸连轧30CrMo,50CrV4钢的相对耐磨性都达到了热轧Q235钢的1.6倍以上。在低应力磨料磨损下,显微切削机制为主要磨损机制,淬火回火态薄板坯连铸连轧低合金耐磨钢具有高硬度因而具有较好的耐磨性能,并在试验钢板硬度高于450HBW以后相对耐磨性明显提高。对比两种牌号的薄板坯连铸连轧低合金耐磨钢的显微组织、硬度、韧性及耐磨性能,30CrMo钢的综合性能较好。50CrV4钢耐磨性能较好,但其冲击韧性较低。     

RE-Nb对铸造3Cr2MoNiWV热锻模具钢组织和力学性能的影响

用扫描电镜、透射电镜和万能电子材料拉伸试验机研究了RE-Nb对铸造3Cr2MoNiWV热锻模具钢组织和力学性能的影响.结果表明:RE-Nb能细化组织,增加位错马氏体的比例,改善回火碳化物和夹杂物的形态、数量及分布.与常规的铸造3Cr2MoNiWV热锻模具钢相比,冲击韧性提高1.9倍,达到了72.3 J/cm2,常温抗拉强度和高温抗拉强度(600 ℃)分别提高了212 MPa和206 MPa,达到1 446 MPa和1 041 MPa,而硬度变化不大.     

Effects of the Process Parameters on the Microstructure and Properties of Nitrided 17-4PH Stainless Steel

The effects of process parameters on the microstructure, microhardness, and dry-sliding wear behavior of plasma nitrided 17-4PH stainless steel were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and wear testing. The results show that a wear-resistant nitrided layer was formed on the surface of direct current plasma nitrided 17-4PH martensitic stainless steel. The microstructure and thickness of the nitrided layer is dependent on the treatment temperature rather than process pressure. XRD indicated that a single α _N phase was formed during nitriding at 623 K (350 °C). When the temperature increased, the α _N phase disappeared and CrN transformed in the nitrided layer. The hardness measurement demonstrated that the hardness of the stainless substrate steel increased from 320 HV_0.1 in the untreated condition increasing to about 1275HV_0.1 after nitriding 623 K (350 °C)/600 pa/4 hours. The extremely high values of the microhardness achieved by the great misfit-induced stress fields associated with the plenty of dislocation group and stacking fault. Dry-sliding wear resistance was improved by DC plasma nitriding. The best wear-resistance performance of a nitrided sample was obtained after nitriding at 673 K (350 °C), when the single α _N-phase was produced and there were no CrN precipitates in the nitrided layer.     

钼钨钒合金化热作模具钢高温回火组织演变

为适应热冲压技术的发展需求,开发了一种新型高热导率高耐磨性能热冲压用模具钢材料。采用扫描电镜（SEM）、透射电镜（TEM）等检测手段对钼钨钒合金化新型模具钢的高温回火性能与组织特征进行了研究。阐明了新型热冲压模具钢回火过程碳化物析出与演变规律。实验结果表明:实验用钼钨钒合金化模具钢材料具有良好的回火二次硬化性能,在500～600 ℃温度区间回火时,回火组织硬度上升;在600 ℃回火出现二次硬化峰值;当回火温度超过600 ℃后,组织软化程度明显,回火硬度开始下降。实验模具钢在高温回火过程中的硬度变化与其合金碳化物的偏聚、析出和聚集长大密切相关。当在560 ℃以下回火时,实验钢组织中未有合金碳化物析出;当回火温度大于560 ℃时,回火组织中开始析出M₂C型碳化物;当回火温度高于600 ℃后开始析出MC型碳化物;当在620 ℃长时间回火后M₂C型碳化物转化为M₆C型碳化物,此时实验钢硬度开始明显下降;而当回火温度高于660 ℃时,新型实验钢组织中主要为M₆C和MC型合金碳化物。      

Hot cracking susceptibility research in BTW1 austenitic high-manganese wear-resistant steel

Baosteel's first BTW1 austenitic high-manganese wear-resistant steel exhibits strong deformation-induced hardening characteristics.Compared with common low-alloy martensitic wear-resistant steels in the market,it has improved impact wear resistance,hard abrasive wear,erosion wear performance,and impact toughness.The metallurgical properties of such austenitic wear-resistant steel lead to the risk of failure because of hot cracking defects in the welded structure.In wear-resistant applications,evaluating hot cracking susceptibility is necessary to avoid the effect of welding defects.In this study,the Varestraint test is used to quantitatively analyze and evaluate the hot cracking susceptibility of BTW1 austenitic high-manganese wear-resistant steel.The test results show that by controlling the content of impurity elements and grain refinement,BTW1 austenitic high-manganese wear-resistant steel effectively reduces hot cracking tendency and has a low incidence of hot cracking under small strain conditions.The developed matching welding process can effectively avoid the influence of hot cracking susceptibility.     

新型化学热处理在连铸结晶器上的应用

新型化学热处理工艺已用于连续铸钢机的结晶器。实践证明 ,经化学热处理的结晶器具有良好的导热性 ,耐磨性 ,抗氧化性和高的热疲劳强度 ,显著延长使用寿命 ,降低成本。用实验数据和现场使用结果 ,分析讨论这些特性     

稀土铈对内生TiC型超级耐磨钢组织性能的影响

 作为耐磨钢研究的新领域,引入高体积分数TiC粒子的超级耐磨钢,虽然能够提升钢的耐磨性,但会降低材料的韧塑性。为了提升超级耐磨钢的综合性能,研究稀土铈对超级耐磨钢组织性能的影响,采用真空感应炉冶炼出不同铈质量分数的试验钢,通过扫描电镜(SEM)、电子背散射衍射(EBSD)、电子探针(EPMA)、硬度测试、低温冲击性能测试、磨损性能测试等手段,研究了铈对试验钢TiC粒子析出行为、组织、力学性能以及耐磨性能的影响。结果表明,热处理后试验钢的组织为回火马氏体。铈可以将高钛耐磨钢中TiC、TiN粒子改性为Ce₂O₂S-TiC、Ce₂O₂S-TiN、CeP-TiC和xCeP·yCe₂O₃-TiC稀土复合粒子。随着铈质量分数的增加,试验钢的强度和硬度变化不大,低温韧性和耐磨性先提高后下降,在铈质量分数为0.002 5%时,其综合性能最佳,相对耐磨性为未添加铈试验钢的1.27倍。     

循环等离子渗氮工艺对38CrMoAl钢渗氮层组织和性能的影响

试验了38CrMoAl钢(%:0.35～0.42C、1.35～1.65Cr、0.15～0.25Mo、0.70～1.10Al)280 Pa 560℃,12 h常规渗氮和170 Pa 560℃3 h快冷至室温循环等离子渗氮对渗氮层组织、硬度、硬度梯度和耐磨性的影响。结果表明,循环等离子体渗氮工艺有利于表层ε相分解,更有利于氮渗入钢中γ′相;在获得相同的渗层表面硬度和硬度梯度下,循环等离子渗氮速度明显高于常规渗氮速度,并改善渗氮后钢的耐磨性。     

钢与TiC颗粒之间界面润湿性分析

 TiC粒子具有高硬度、高熔点和高热力学稳定等特点,以TiC粒子作为增强相具有提高钢基体强度、耐高温和耐磨损等性能的潜力,近年来相关钢种的开发受到越来越多的关注。增强相颗粒与钢基体之间良好的润湿性是提高界面结合强度、防止颗粒在磨损过程中脱落的关键。因此,为了明确TiC粒子与钢基体之间的润湿程度,指导以TiC为增强相的耐磨钢的开发,采用高温座滴法观察钢液滴在TiC基片上的铺展行为,采用电子探针分析钢与TiC颗粒之间微区的元素分布,并结合热力学计算,探究高温下钢液与TiC之间界面润湿行为。结果表明,钢液与TiC之间的润湿性很好,在升温以及保温过程,钢样熔化后能通过TiC基片中的微孔快速渗入到基体内部,表现为钢样向下“坍塌”,直至钢样从观察窗口中完全消失。钢液进入TiC基片内部的同时,钢中氮元素向周围TiC相扩散。电镜分析表明钢液与TiC颗粒界面上没有产生新的相。TiC(TiN)与铁组成的二元相图表明,与TiN相比,TiC在钢液中有较大的溶解度,这解释了TiC-钢系统比TiN-钢系统润湿性好的原因。钢液与TiC颗粒之间的界面润湿性好且不发生化学反应,保证了TiC颗粒可作为增强相来提高钢的耐磨性能。为TiC颗粒与高钛钢之间的润湿性研究提供借鉴,为高钛耐磨钢成分的设计提供理论指导。     

Revealing the Role of Cerium on Precipitation Behavior of In Situ TiC Particles and Wear Resistance of High-Titanium Wear-Resistant Steels

Compared to conventional martensitic wear-resistant steels of the same hardness, high-titanium wear-resistant steels with in situ TiC particles can significantly improve wear resistance. However, micron-sized TiC particles will decrease the toughness of high-titanium wear-resistant steels. Here, in order to improve wear resistance without reducing impact toughness, we incorporate 0.0025% cerium elements into high-titanium wear-resistant steels. Compared with no cerium steel, the steel containing cerium is demonstrating comparable mechanical properties, with the yield strength of 1283 MPa and impact toughness of 35.6 J, and the wear performance of the steel containing cerium is 1.78 times that of the steel with no cerium. The results show that with the addition of cerium the effective grain size of the steel decreases, and yield strength and toughness increase. The addition of cerium can form intermetallic compounds of Ce₂O₂S, which are used as heterogeneous nuclear particles in TiC to form rare earth composite particles calculated by the 2D mismatch theoretical model of Bramfitt. As the average spacing of the reinforcing phase particles in the steel decreases, the effective grain size of the steel decreases, and the number of reinforcing phase particles increases, the wear resistance of the steel with the addition of cerium is optimized.     

表面处理对H13钢抗动态热熔损性能的影响

 为了延长热作模具钢在铝合金压铸过程中的使用寿命,对H13热作模具钢进行了气体软氮化、蒸汽氧化及其氮氧复合处理。采用熔损失重法,通过称量各种表面处理H13钢熔损试验前后的质量,对其抗动态熔损性能进行了比较。结果证明,表面处理能显著提高H13钢的抗熔损性能,尤以氮氧复合处理效果最佳。     

冷轧带钢板形辊激光熔覆表面强化试验

 板形辊是生产高端冷轧带钢的关键装备,其表面性能对保证带钢产品表面质量和提高其自身使用寿命都至关重要。为了提高板形辊辊面的硬度和耐磨性,通过激光熔覆铁基耐磨合金的方式对其进行了表面强化处理,通过试验对比了激光熔覆强化辊面与淬火强化辊面性能。结果表明,在满足硬度要求的前提下,熔覆层的耐磨性比淬火层至少提高20.9%。为研发冷轧带钢板形辊表面强化技术开辟了一条新途径。     

H13型热作模具钢表面改性技术研究进展

 在工业中,模具的变形、磨损和疲劳失效普遍存在,严重影响了生产效率和产线安全。为了更好地了解和分析模具失效的原因,改善模具的性能,提高其使用寿命,通过介绍国内外H13型热作模具钢的表面改性技术及研究现状,总结了激光加热处理、热喷涂处理、化学热处理3类表面改性技术的特点及在改善热作模具钢表面性能方面的研究成果。探讨了不同表面处理工艺对该热作模具钢表面性能的影响,对不同处理技术应用于该热作模具钢表面改性的优缺点进行了分析,并对该热作模具钢表面改性技术的发展方向进行了展望。     

4Cr5MoSiV1 钢热挤模真空渗氮工艺试验研究

分析了4Cr5MoSiV1钢热挤模经低真空氮化的渗层组织及其显微硬度分布、工艺运行特点及其生产应用情况,以期推动真空渗氮工艺在我国铝挤压模具的推广应用,提高铝型材热挤压模使用寿命,并实现绿色热处理的目标。     

4Cr5MoSiV10钢热挤模真空渗氮工艺试验研究

分析了4Cr5MoSiV1热挤模经低真空氮化的渗层组织及其显微硬度分布、工艺运行特点及其生产应用情况，以期推动真空渗氮工艺在我国铝挤压模具的推广应用，提高铝型材热挤压模使用寿命，并实现绿色热处理的目标。     

VARIOUS FACTORS AFFECTING THE WEAR OF STEEL DIES USED FOR THE COMPACTING OF IRON POWDER

Abstract

Small cylindrical iron powder compacts have been produced in series of ～ 75 000 specimens, using an automatic compacting press running at a speed of 33 strokes/min. Die-wear rates were determined, as influenced by powder type, compacting pressure, compact density, type and hardness of die steel, and punch/die clearance. Simultaneously, the ejection forces were continuously recorded.

No substantial difference was found between the die-wear rates of common iron powder grades of an atomized or a sponge type, but an electrolytic grade of especially compact particle structure gave a lower rate. Die wear increases in roughly linear proportion both with the number of compacts and with the compacting pressure.

Steel type and hardness of the die had a pronounced influence upon die-wear behaviour, dies of higher hardness yielding lower wear rates. Unsuitable heat-treatment can cause high wear rates even though it might produce high die hardnesses.

A punch/die clearance of 10 μm resulted in the most favourable die-wear behaviour. At a clearance of only 5 μm the punches became stuck in the die very quickly; at clearances of 25 and 45 μm severe cladding of the die-bore surface with iron from the compacts occurred after 40 000-50 000 strokes.

The following, partly interacting, phenomena were found to be contributory factors in the die-wear mechanism: abrasion, cladding, surface cracking, and chipping. It proved impossible to establish a reliable correlation between ejection forces and die-wear rates.     

Effect of Single and Duplex Thin Hard Film Coatings on the Wear Resistance of 1.2343 Tool Steel

In aluminum extrusion process, tool steels used as die materials suffer from mechanical, thermal and tribological stresses causing plastic deformation, wear and heat checking during hot metal flow. Thin hard film coatings like TiN, (Ti,Al)N and CrN are preferred in order to improve the surface properties of the tools. These coatings can reduce the friction force, minimize the adhesive interaction between the die and billet pairs and decrease the plastic deformation of the tool. In this study, effect of single (CrN and AlTiN) and duplex (CrN + AlTiN) thin hard films on the hot wear behavior of DIN 1.2343 tool steel was investigated. Wear tests were performed both at room temperature and elevated temperature to simulate the conditions of aluminum extrusion process. Based on the evaluation of coefficient of friction values, specific wear rates and worn surface examinations, the duplex coating, which had the best performance in the RT wear test showed good resistance to high temperature wear under the simulated aluminum extrusion conditions.     

Cr元素对热轧耐磨钢显微组织和耐磨性的影响

对两种热轧耐磨钢(Cr质量分数分别为0和0.65%)经过在线层流冷却后的组织性能进行了研究,使用磨损试验机MLG-130在60 N载荷下进行摩擦磨损试验,利用场发射扫描电镜分别对试样磨损表面进行观察。两种耐磨钢冷却后组织为铁素体和马奥岛,由于Cr元素的加入,含Cr钢组织中以马奥岛为主,体积分数为82.6%。此外,在不同磨损时间下含Cr钢的耐磨性均优于无Cr钢。经过0.5、1和1.5 h磨损后,含Cr钢的磨损失重分别为0.357 8、0.769 5和1.427 2 g,其耐磨性分别为1.40、1.30和1.05 g-1。无Cr钢磨损表面出现了明显的犁沟和剥落坑,磨损机制主要为微犁削和微断裂。而含Cr钢由于屈服强度和表面硬度更高,塑性变形被抑制,因此磨损表面更加光滑平整,主要磨损机制为微切削和微断裂。     

Heat Treatment Optimization and Properties Correlation for H11-Type Hot-Work Tool Steel

The aim of this research was to determine the effect of vacuum-heat-treatment process parameters on the material properties and their correlations for low-Si-content AISI H11-type hot-work tool steel using a single Circumferentially Notched and fatigue Pre-cracked Tensile Bar (CNPTB) test specimen. The work was also focused on the potential of the proposed approach for designing advanced tempering diagrams and optimizing the vacuum heat treatment and design of forming tools. The results show that the CNPTB specimen allows a simultaneous determination and correlation of multiple properties for hot-work tool steels, with the compression and bending strength both increasing with hardness, and the strain-hardening exponent and bending strain increasing with the fracture toughness. On the other hand, the best machinability and surface quality of the hardened hot-work tool steel are obtained for hardness values between 46 and 50 HRC and a fracture toughness below 60 MPa√m.