冷处理对冷轧辊用86CrMoV7钢抗接触疲劳性能的影响

冷轧工作辊的抗接触疲劳性能是其抵抗早期失效的主要性能之一。它与轧辊表层组织结构和残余应力状态有关。组织结构和残余应力取决于轧辊的热处理工艺。笔者已就淬火温度对86CrMoV7钢抗接触疲劳性能的影响进行了研究。为进一步了解残余奥氏体和残余应力的作用,本工作就冷处理对86CrMoV7钢的抗接触疲劳性能的影响进行了研究。将试样在930℃油中淬火,并于0、-35、-74和-105℃冷处理,150℃回火。测量各组试样的接触疲劳寿命、残余奥氏体量、残余应力和硬度。并对显微组织和剥落断口进行了研究。结果表明,淬火后不经冷处理和-35℃冷处理的试样具有高的接触疲劳寿命,其余各组寿命均较低。随冷处理温度下降,残余奥氏体量减少,硬度增高,残余应力变化不大。这些变化是由于冷处理时奥氏体向马氏体转变的缘故。接触疲劳试验后,试样中残余奥氏体量进一步减少,硬度和残余应力都有增加。这反映了接触疲劳过程中形变和相变的综合效果。研究认为,86CrMoV7钢淬火组织中,残余奥氏体的稳定性是影响其抗接触疲劳性能的重要因素之一。一定量的稳定的残余奥氏体与高的表面硬度和较高的残余压应力相结合将有利于提高钢的接触疲劳性能。主要结论是冷处理可以消除淬火钢中不稳定的残余奥氏体,并可以提高钢的硬度和残余压应力。因而,对提高86CrMoV7钢的抗接触疲劳性能是有利的。     

表面喷丸与Fe~+注入协同增强Ti13Nb13Zr合金的生物摩擦学性能

为改善Ti13Nb13Zr合金表面的生物摩擦学性能,选用表面喷丸和Fe~+注入改性Ti13Nb13Zr合金表面。利用X射线衍射仪(XRD)分析改性层的相组成和残余应力,使用纳米显微力学探针测定改性层的纳米硬度,采用摩擦磨损试验机研究改性层的摩擦因素,选用扫描电子显微镜(SEM)观察改性层的磨痕形貌。表面喷丸与Fe~+注入的协同作用下,Ti13Nb13Zr合金表面出现了增强相Fe_2Ti,且离子注入能量的增加更有利于Fe_2Ti的形成。随着注入能量和剂量的增加,改性层的残余应力和纳米硬度相较于未离子注入的显著增加,残余应力最高从-453MPa增到-741 MPa,增幅达163.6%;纳米硬度最高从4.80增到10.63 GPa,增幅达121.5%。此外,在人工唾液和透明质酸钠溶液润滑下,改性层的磨损逐渐减缓,生物摩擦学因素分别从0.40降至0.34,从0.34降到0.29,下降幅度分别为17.1%与14.7%。表面喷丸与Fe~+注入的协同作用能够有效地提高Ti13Nb13Zr合金表面改性层的减摩抗磨性能。     

热处理对TRIP 590钢微观组织及力学性能的影响

采用Gleeble3800热模拟机对TRIP钢拉伸试样进行不同工艺条件的快速热处理模拟实验,并采用金相分析、显微硬度测试等方法对试样进行组织观察和性能测试,目的是通过适宜的热处理工艺促使材料微观组织中出现适量的残余奥氏体组织,增强该材料在变形过程的相变诱导塑性(TRIP)效应,强化材料结果表明:在两相区内,TRIP钢中的残余奥氏体含量随着退火温度和退火时间的增加而增大,以25℃/s缓慢加热到700℃,再以150℃/s的速率快速加热到820℃保温120s后淬火处理,处理后的试样,残余奥氏体体积分数达到13％,显微硬度最高,达到262HV.     

75CrMnMo铸钢轧辊激光熔凝强化的组织及性能分析

应用5kW连续CO2激光器对铸钢轧辊进行激光熔凝强化处理并进行显微组织分析和硬度测试。结果表明，其试样剖面组织区域分为激光熔凝强化区(细小马氏体 残余奥氏体 碳化物)，激光相变强化区(马氏体 残余奥氏体 碳化物)，过渡区和母材4个区域。激光处理后可达70～85 HSD。熔凝区和相变硬化区的淬硬深度依工艺参数不同，可达1～2mm。此工艺可以作为提高轧辊过钢量的一种途径。     

M50NiL钢磨削表面完整性特征及变质层厚度表征方法

通过透射电子显微镜确定了M50NiL钢渗碳后磨削表面变质层厚度,同时利用扫描电子显微镜、原子力显微镜、显微维氏硬度计、X射线残余应力测定仪等设备表征了M50NiL钢磨削表面完整性特征.结果表明:磨削在渗碳硬化层表面构建了一个表面变质层,该变质层组织的基本特征是晶粒细化和变形,在选区电子衍射图上显示为拉长模糊的多晶环;变质层厚度约0.5μm,残余压应力和硬度略有升高,表面应力集中系数较低.      

Nb含量对TRIP钢组织和性能的影响

利用Gleeble-1500热模拟机对不同Nb含量的TRIP钢的热轧过程进行了热模拟实验.研究了Nb含量对TRIP钢组织和性能的影响.实验结果表明：Nb的加入使得实验钢的组织得到细化,贝氏体量增多;增加Nb含量,残余奥氏体量和残余奥氏体含碳量有所降低,宏观维氏硬度值增加;Nb的质量分数为0.014%时,残余奥氏体量为19.2%、残余奥氏体含碳量为1.422%、宏观维氏硬度为258HV和抗拉强度为851 MPa.     

激光强化对球墨铸铁性能的影响

针对球墨铸铁硬度低、耐磨性不足的问题,对其进行了激光强化试验研究,摸索工艺参数对强化硬度的影响,并利用金相显微镜、X射线应力仪及磨损试验机,重点研究了激光强化后淬硬层金相组织、残余应力与耐磨性的变化。结果表明,激光强化后,球墨铸铁表面硬度显著提高,淬硬层组织为隐针马氏体+珠光体+重构碳化物+少量残余奥氏体,残余应力为压应力,整体耐磨性和抗疲劳能力显著提升。     

60CrMnMo激光表面处理的组织与性能

应用3kW连续CO2激光器对60CrMnMo轧辊钢在涂敷不同合金粉时进行表面激光熔凝处理,处理后对组织、硬度、脆性进行观察与测试.结果表明,处理后可获得熔凝层、硬化层、过渡层及基体四层组织;涂敷黑涂料时能得到最高的熔凝层与硬化层硬度,表面熔凝层硬度最高可达880 HV0.1,硬化层硬度最高可达997 HV0.1,涂敷Ni60合金粉对改善处理层的脆性有较好效果.     

快速热处理超细贝氏体钢构筑梯度结构研究

心部高韧性、表面高硬度的材料是抗冲击载荷轴承、齿轮等关键零部件的重要要求。以超细贝氏体为对象，进行局部快速热处理，得到局部高硬度、心部高韧性的梯度结构，研究快速热处理过程中超细贝氏体组织的相变行为，以及梯度组织和性能变化规律。结果表明，超细贝氏体钢在加热时，残余奥氏体分解为铁素体和碳化物，贝氏体铁素体粗化，在快速热处理中存在相变滞后。超细贝氏体钢经过局部快速热处理后形成一个组织和性能梯度过渡的结构。硬化区组织由淬火得到的马氏体和残余奥氏体组成，随着深度增加，组织中的马氏体含量减少，初始超细贝氏体的回火产物逐渐增加。硬化区的硬度高达63HRC,随着深度增加逐渐降低至38HRC,硬度相对基体下降约6HRC。     

深冷处理对H13钢组织结构和热稳定性的影响

 为了研究深冷处理对H13热作模具钢热稳定性的影响及组织演化规律,利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等对经不同热处理工艺处理后H13热作模具钢的热稳定性及显微组织进行了表征。结果表明,深冷处理促使部分残余奥氏体转变为马氏体,导致深冷处理后试验钢的硬度高于淬火态试验钢的硬度。经深冷处理后试验钢在540 ℃回火20 h过程中其硬度均比常规热处理的试验钢硬度高,深冷处理的试验钢具有更好的热稳定性。与常规热处理的试验钢相比,深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,导致深冷处理的试验钢回火后马氏体基体中碳的质量分数降低。透射电镜结果显示,试验钢在回火过程中析出的大量弥散分布的纳米级M₂₃C₆型碳化物,经长时间回火后碳化物粗化致使试验钢硬度随着回火时间的增加而下降。     

卷取机夹送辊表面堆焊层组织性能研究

采用埋弧堆焊工艺在Q235B表面堆焊8-10mm的Cr8系列新型熔覆材料,测定其耐磨性和硬度变化,分析熔覆金属的组织形貌和高温工况下的合金元素扩散。研究结果表明,熔覆金属打底层主要是以铁素体为主,伴随着少量的贝氏体。盖面层的焊态组织主要为马氏体和残余奥氏体,伴有少量的回火马氏体,同时在枝晶马氏体间可见少量较小的碳化物。经550℃回火后其盖面层组织为回火马氏体和残余奥氏体,碳化物析出相均布较焊态呈增多趋势。焊态硬度值为530-580HV300,回火后硬度值为720-830HV300,磨损失重是45#淬火钢的0.31倍。在使用3个月后发现在熔覆层表面出现了元素偏移并形成了由Cr2O3、WO等组成的氧化膜,降低了夹送辊的粘钢倾向,提高使用寿命。     

Research on the inwall shot blasting of the S30432 high-pressure boiler tube

Inwall shot blasting is a method of improving the surface hardness and high temperature oxidation resistance of the S30432 high-pressure boiler tube.The differences on residual stress,sub-grain size,micro-hardness and structure between the S30432 inwall shot-blasting tube produced by Baosteel with six technological process parameters and the imported super 304H were studied systematically by contrast test research.It has been demonstrated that the S30432 obtains a higher residual stress,a deeper distributed layer and a better sub-grain size of the inwall field shot-blasting layer;the martensite content of the shot-blasting surface was low;and micro-hardness and structure refinement were better.After 2000 h' oxidation test under the 650℃/26MPa steam condition,steam oxidation resistance of the Baosteel steel tube shot-blasting surface was higher,the oxide layer was thinner,and was well combined with bulk material.     

表面纳米化AISI H13钢的渗铬处理及其耐磨性

对表面纳米化（SNC）处理后的热作模具钢AISI H13钢进行渗铬处理,用扫描电子显微镜、透射电子显微镜、纳米压痕仪和摩擦磨损试验机研究了渗铬层成分、微观结构、硬度和耐磨性。结果表明,经600及1 050℃的复合渗铬处理后,SNC样品表面形成了厚约30μm的连续渗层,是经相同复合渗铬处理的粗晶样品上渗层厚度的3倍。受益于渗铬层中较小的晶粒尺寸和较高的硬度,加之其成分、结构和力学性能在较大深度范围内较为平缓的梯度变化,SNC H13钢经渗铬处理后耐磨性得到显著提高。     

Microstructure Evolution and Wear Resistance Improvement of Ultrasonic Peened M50 Steel via Electromagnetic Shocking

Herein, the effect of electromagnetic shocking treatment (EST) on microstructure evolution and wear resistance of M50 steel treated by ultrasonic shot peening (USP) is investigated. The microstructure observation indicates that the EST promotes the precipitation of nanoscale carbides. The average grain size decreases slightly and the submicron grain layer increases after EST. The low-angle grain boundaries generated by USP will transform into high-angle grain boundaries, thereby refining the grains on the surface during EST. In addition, the surface hardness of USP-M50 steel decreases slightly, accompanied by the reduction of surface residual stress after EST. The wear resistance results indicate that the wear loss of the EST specimens decreases by 15.7% comparedwith the specimens after USP. The improvement of wear resistance induced by EST is attributed to the increased fine precipitations. These precipitations hinder the grinding of abrasive particles into the matrix and connect with wear debris and oxide particles to form well consolidated self-lubricating films to prevent wear losses. The refinement of surface structure is another important reason for the improvement of wear resistance.     

Wear of hard-turned AISI 52100 steel

High-precision machining such as hard turning changes the surface and the material properties of steel alloys. The near-surface material properties have been predicted from the known hard-turning cutting conditions. The effect of the predicted hard-turned surface and material properties on wear performance was analyzed in detail to develop a process-performance model. A sliding block-on-cylinder wear tester was used for the purpose of testing the wear performance of AISI 52100 bearing steel. The microstructure, surface roughness, residual-stress field, and loading conditions from each wear test were used to develop the process-performance model. The effect of microstructure on the wear performance of hard-turned steel showed that the white layer and overtempered martensite (OTM) had a higher wear resistance than martensite. The wear-mechanism dependence on the surface hardness was attributed to this increase in wear performance. The near-surface residual stress of the material was shown to become more compressive as the material wore down. The applied normal loads affected the surface roughness, residual stresses, and, in turn, the wear performance of the material. A process-performance model was developed to predict the wear performance of hard-turned steels, which considers the machining process and the operating conditions in sliding wear.     

热处理工艺和爆炸预硬化对高锰钢ZGMn13VTiMoRE组织和耐磨性的影响

运用金相、透射及扫描电镜和冲蚀磨损等试验方法，研究了不同水韧及时效工艺处理和爆炸预硬化对高锰钢组织和耐磨性的影响，提出了优化热处理工艺。研究结果表明，经优化热处理工艺和爆炸预硬化处理后，使ＺＧＭｎ１３ＶＴｉＭｏＲＥ钢得到细小，均匀的奥氏体晶粒，弥散分布的第二相质点，一定厚度的预硬化层和存在于基体中的大量形变层错及孪晶等，其耐磨性可提高４０％。     

Influence of the quenching temperature on the phase composition,structure, and wear resistance of 150XHM steel

The influence of the quenching temperature on the quantity of residual austenite, its stability, and its ease of deformational martensitic transformation in 150XHM steel is studied. In the addition, the hardening and abrasive-wear resistance of the steel are studied as a function of the quenching temperature. The dependences of the steel’s hardening and wear resistance on the quenching temperature are of opposite form. The drop in hardness with increase in quenching temperature is due to increase in the content of residual austenite. At the same time, the relative ease of deformational martensitic transformation in the metastable residual austenite results in increase in wear resistance and microhardness of the worn surface.     

含钛中锰钢淬火-配分组织及力学性能

 为了研究淬火-配分含钛中锰钢的组织与力学性能,借助扫描电子显微镜,透射电子显微镜、电子背散射衍射技术与万能拉伸试验机、磨粒磨损试验机等,分析与测试了含钛中锰钢在165~240 ℃淬火380 ℃配分处理后组织、强度、塑性与磨粒磨损性能。结果表明,试验钢淬火-配分组织主要为板条状一次马氏体、块状二次马氏体及残余奥氏体,同时含有大量微米级TiN和纳米级(Ti,Mo)C及TiN-(Ti,Mo)C复合析出相。190 ℃淬火380 ℃配分后残余奥氏体体积分数最高为12.5%。试验钢不同温度淬火与配分后屈服强度均大于1 000 MPa,抗拉强度均大于1 500 MPa,硬度从482.5HV增大到542.2HV,伸长率范围为9.2%~14.5%,在165~190 ℃淬火-配分处理后其抗磨粒磨损性能优于220~240 ℃淬火-配分钢。磨损机制主要是塑性变形和疲劳破坏,磨损过程中残余奥氏体发生应变诱导马氏体相变(TRIP)效应,析出相颗粒阻断基体塑性变形过程犁沟的前进和刮削行为,含钛中锰钢通过淬火-配分引入一定体积分数的残余奥氏体,有利于提高钢的强塑性与抗磨损性能。结合力学性能指标,含钛中锰钢最佳淬火-配分工艺为900 ℃奥氏体化30 min,190 ℃淬火,380 ℃配分10 min。     

45钢双层辉光等离子渗Nb的组织及摩擦性能研究

 采用双层辉光等离子表面合金化技术对45钢进行表面渗Nb处理,用OM、SEM和XRD分析了渗Nb层的显微组织、化学成分及其相组成,测试了渗Nb合金层的显微硬度和表面耐磨性。结果表明：经过离子渗Nb处理后可获得约10μm的表面合金层;渗层中Nb含量随渗层深度呈梯度变化,渗层与基体结合牢固;XRD表明其表面形成Fe3Nb3C,Fe2Nb,NbC和Nb6C5等相。摩擦磨损试验表明：Nb的渗入使45钢基体摩擦系数由0.80左右降到了0.15,磨损失重仅为基体的18%,大大提高了耐磨性能。     

Study of Wear Stabilisation in Cryoprocessed Cobalt-Based High Speed Steel

Cryogenic treatment is employed for high speed tool steels in order to enhance their wear resistance. The improvement in wear resistance is associated with a decrease in retained austenite and or by formation of eta-carbide/nano-scale carbides. In the present work, a complex alloyed high speed tool steel (M35) specimens were hardened at 1,200?°C, triple tempered at 400?°C, cryosoaked at ?185?°C for 4?C48?h and soft tempered (100?°C). The microstructure of the samples were characterised for hardness, carbide density, impact energy, wear loss and residual stress. Influence of these measured parameters on wear behaviour was studied to understand underlying wear mechanism. The cryotreated specimens exhibited mild to stable wear transition at 16?h and then subsequent wear stabilisation for all higher cryosoaking intervals.