采煤机堆焊涂层截齿热处理工艺研究

35CrMnSiA钢采煤机截齿加热至930℃在10％NaOH碱液中淬火，可以获得较多的板条马氏体。通过对截齿冲击韧度、小能量多冲击抗力和截齿工作状况的分析，发现35CrMnSiA钢在370℃～410℃之间存在回火脆性，采用425℃回火，截齿强韧性较好。截齿采用先热处理而后分层堆焊的工艺，其强度、硬度和耐磨性都得到提高。     

截齿形变热处理的组织观察

对截齿进行形变热处理，并对其形变热处理后的组织进行了观察．结果表明：经50％形变后，获得了弯曲而相互交错马氏体板条；形变淬火态位错密度较高，回火态位错结构发生了变化，形成了位错胞壁；大量细小而弥散的碳化物在马氏体内部及在位错线上析出。截齿的力学性能满足生产需要。     

提高采煤机截齿质量的新途径

截齿是煤矿采煤机螺旋滚筒上截割煤层的刀具，要求其齿体具有较高的强度、冲击韧度和耐磨性，嵌镶在齿体上的硬质合金在截割各种煤层和夹研时不能脱落和破碎。目前国内生产截齿普遍采用“下料→齿体模锻→预备热处理→机加工→高频针焊→整体加热等温淬火→回火→涂油”的工艺流程。实践证明，该工艺流程存在浪费能源、增加成本、降低劳动生产率的缺点，而且因淬火加热温度不能超过焊料熔点（897℃），针焊后再高温加热，降低了焊缝的剪切强度。经试验用锻后余热退火作预备热处理，用盐浴炉快速加热针焊等温淬火来代替“高频钎焊～整体加热…     

热处理工艺对截齿钎焊接头强度的影响

为获得采煤机用截齿钎焊接头的优良性能，作者研究了钎焊后热处理工艺参数对钎缝抗剪强度的影响。试验表明，高温区停留时间在保证钎焊时钎料充分熔化的前提下越短越好；冷却速度对接头的强度有较大影响，一般情况下，钎焊后由880℃冷却到200℃的时间应控制在5～20min之间；回火温度在350～450℃之间抗剪强度有低谷区。截齿钎焊采用HL105钎料，配以合适的钎剂能获得较理想的接头性能。     

热处理工艺截齿钎焊接头强度的影响

为获得采煤机用截齿钎焊接头的优良性能，作者研究了钎焊后热处理工艺参数对钎缝抗剪强度的影响。试验表明，高温区等停留时间在保证钎焊时钎料充分熔化的前提下越短越好；冷却速度对接头的强度有较大影响，一般情况下，钎焊后由８８０℃冷却到２００℃的时间应控制在５～２０ｍｉｎ之间；回火温度在３５０～４５０℃之间抗剪强度有低谷区。截齿钎焊采用ＨＬ１０５钎焊，配以合适的钎剂能获得较理想的接头性能。     

时效对Cu-Zn-Ni合金组织和剪切强度的影响

结合截齿钎焊后的热处理工艺,对Cu-Zn-Ni合金热处理后的组织和剪切强度进行了研究。结果表明,时效后,组织是由以Cu为基的α固溶体和以CuZn为基的β＇固溶体组成;与固溶处理相比,时效后α相变得更为细小,β^’相的含量略有增多,这是由于时效时,析出相对基体的切割致使其组织更为细密。在200~450 ℃的时效温度范围内,随着时效温度的上升,Cu-Zn-Ni合金组织中的α相越来越细小,β^’相的含量越来越少,合金的剪切强度增加。     

BCu48ZnNi合金钎料的组织、力学性能与使用特性

为提高矿用截齿钎焊连接性能,优化与协调截齿生产时的钎焊和截齿体热处理工艺,研究了锌白铜硬钎料BCu48Zn Ni的组织和性能,考察了其使用特性。对BCu48Zn Ni钎料进行重熔凝固与热处理,测试了不同状态下的组织和性能。结果表明,BCu48Zn Ni合金在不同状态下均为两相组织,快冷与时效可使组织细化并提高硬度。采用中频感应方法进行截齿钎焊试验,考察了焊后冷却方式和截齿热处理对钎焊缝抗剪强度的影响。试验发现,焊后空冷的BCu48Zn Ni合金钎焊缝抗剪强度高于缓冷与快冷,焊后高温回火能保持较高抗剪强度。综合分析表明,BCu48Zn Ni钎料具有优良的截齿钎焊特性,用其做钎料进行截齿生产须先钎焊后调质。     

深冷处理对镐型截齿硬度、耐磨性和冲击性能的影响及其优化

在镐型截齿传统钎焊—热处理工艺中引入深冷处理技术,形成钎焊—热处理—深冷处理新工艺,并以深冷温度和深冷时间为深冷处理主要工艺参数,使用全因子方法设计深冷处理试验方案,测试镐型截齿齿头部位和齿体部位硬度,测试镐型截齿齿体冲击性能,对镐型截齿整体进行截割岩料试验测试耐磨性,以研究深冷处理对镐型截齿硬度、耐磨性和冲击性能的影响规律,并寻求最优深冷处理工艺。结果表明,深冷处理对镐型截齿硬度影响不显著,对冲击性能有轻微不利影响,但显著提高了镐型截齿的耐磨性。镐型截齿综合性能最优时的深冷处理工艺为深冷温度-196 ℃、深冷时间12 h,此时冲击吸收能量仅降低1.2 J,而耐磨性提高41.6%。     

钛合金的形变热处理(续)

四、低温形变热处理对钛合金进行低温形变热处理的目的是提高强度。通常作法是淬火+冷变形或温变形+时效。低温形变热处理适于制造钛合金薄板、薄壁管材、线材和采用高温形变热处理生产时在工艺上有困难、或者不能用高温形变热处理来生产的其它半成品。     

高温短时Ti750合金形变热处理工艺研究

通过形变热处理工艺试验,结合材料力学性能和微观组织分析,研究高温短时Ti750合金形变热处理工艺。结果表明:形变热处理工艺可明显提高Ti750合金常温和高温力学性能,(850～900)℃变形+780℃/1h时效处理工艺,可使Ti750合金强度、塑性得到较大幅度提高。     

Properties of ausformed austempered ductile iron (AADI) containing Ni

Abstract

The abrasion wear behaviours of Ausformed Austempered Ductile Iron (AADI) and conventional Austempered Ductile Iron (ADI) were investigated. The effects of both Ni content and rolling reduction during the ausforming process on the wear resistance of AADI and ADI were studied. The ausforming process created a finer and more homogeneous ausferrite structure that had a direct influence on the mechanical properties of AADI. Maximum hardness and tensile strength were obtained with 35% rolling reduction. On the other hand, ductility and impact strength were reduced with increasing rolling reduction during the ausforming process. AADI showed superior abrasion wear resistance because of its finer and harder structure.     

EFFECT OF DYNAMIC RECRYSTALLIZATION ON SHAPE MEMORY EFFECT IN Fe－Mn－Si BASED ALLOYS

ＥＦＦＥＣＴＯＦＤＹＮＡＭＩＣＲＥＣＲＹＳＴＡＬＬＩＺＡＴＩＯＮＯＮＳＨＡＰＥＭＥＭＯＲＹＥＦＦＥＣＴＩＮＦｅ－Ｍｎ－ＳｉＢＡＳＥＤＡＬＬＯＹＳ￥Ｌ．Ｊ．Ｒｏｎｇ;Ｙ．Ｙ．ＬｉａｎｄＣ．Ｘ．Ｓｈｉ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｔａｌＲｅｓｅａｒｃｈ,Ｃ...     

Effects of ausforming temperature on bainite transformation,microstructure and variant selection in nanobainite steel

The bainite transformation behavior after plastic deformation of austenite, i.e., ausforming was studied by in situ neutron diffraction and ex situ experiments, and the effects of ausforming temperature was made clear. Ausforming, at a low temperature (573 K) was found to accelerate bainite transformation and produce a characteristic microstructure, whereas at a high temperature (873 K), ausforming had little influence. The reason for the different results stems from the dislocation structure introduced in austenite; planar dislocations remaining on the active slip planes are believed to assist bainite transformation, accompanied by strong variant selection. The variant selection rule that focuses on Shockley partial dislocation was verified from electron backscatter diffraction results.     

New insights to the promoted bainitic transformation in prior deformed austenite in a Fe-C-Mn-Si alloy

The varying trends of the amount and rate of bainitic transformation with strains at low temperature were investigated through metallography, X-ray diffraction and dilatometry. The results show that deformation at 573 K promotes bainitic transformation, whereas the promotion degree on bainite transformation by ausforming is nonlinear with strains. The amount of bainite in deformed austenite first increases and then decreases with the increase of strains. There exists a maximum value of the promotion effect corresponding to a critical small strain at a low temperature. Bainitic transformation rate can be increased by ausforming at low temperature, whereas a large strain weakens the acceleration effect. The amount of bainite in deformed materials is synthetically depended on the effect of enhanced nucleation and repressed growth. In addition, the volume fraction of retained austenite is not completely consistent with carbon content, indicating that ausforming plays a important role in determining the amount of austenite.     

奥氏体变形条件下低碳微合金钢中的贝氏体相变

采用Gleeble-1500热模拟机对低碳Mn-Nh-Ti钢进行了奥氏体区变形和变形后的冷却试验,借助于光学显微镜和扫描电镜分析了变形和冷却速度对显微组织的影响。结果表明,随着奥氏体形变量的增大,奥氏体向铁素体的相变增加,向贝氏体的相变减少,贝氏体中的铁素体和小岛由细长条状逐渐向近等轴状变化,铁素体板条间的小岛逐渐变化为存在于某些铁素体的晶界上。随着变形后的奥氏体冷却速度增大,铁素体量减少,贝氏体量增加,粒状贝氏体也逐渐由板条贝氏体所取代。     

Thermomechanical treatment of austempered ductile iron

The production of lightweight ferrous castings with increased strength properties became unavoidable hter aluminum and magnesium castings. The relatively new ferrous casting alloy ADI offers promising strength prospects, and the thermo-mechanical treatment of ductile iron may suggest a new fluence of thermomechanical treatment,either by ausforming just after quenching and before the onset of austempering reaction or by cold rolling after of this work, ausforming of ADI up to 25％ reduction in height during a rolling operation was found to add a mechanical processing component compared to the conventional ADI heat treatment, thus increasing the rate ics of ausferrite formation was studied using both metallographic as well as XRD-techniques. The effect of ausforming on strength was quite dramatic (up to 70％ and 50％ increase in the yield and ultimate strength respectively). A mechanism involving both a refined microstructural scale and an elevated dislocation density was suggested. Nickel eformation is necessary to alleviate the deleterious effect of alloy segregation on ductility.luence of cold rolling (CR) on the mechanical properties and structural characteristics ofADI wasinvestigated. The variation in properties was related to the amount of retained austenite nsformation. In the course of tensile deformation of ADI, transformation induced plasticity (TRIP) takes place, indicated by the increase of the instantaneous value of strain-hardening exponent with o partial transformation of γr to martensite under the CR strain. Such strain-induced transformation resulted in higher amounts of mechanically generated therefore increased, while ductility and impact toughness decreased with increasing CR reduction.     

X70无缝酸性线管的形变淬火和回火工艺

对X70大口径厚壁无缝酸性线管形变淬火+回火处理工艺和普通淬火+回火工艺进行了对比分析。结果表明,形变淬火+回火工艺显著提高了强度,并具有良好的韧性,使产品的性能完全满足要求,同时还降低了生产成本。     

精密成形模具材料热处理工艺研究

为满足轻合金等温精密成形模具的工作条件要求,通过合理选择综合性能符合要求的模具材料H13钢,采用不同的热处理工艺对试样进行退火、淬火、回火试验,测试其硬度、冲击韧性,并观察金相组织,作为H13钢模具工艺优选的依据.试验结果表明H13钢在最佳完全退火温度、淬火温度、回火温度下可得到最优综合性能.     

钢经形变热处理的组织控制及强韧性改善

本文主要论述了控制轧制、过冷奥氏体形变热处理的形变诱发塑性对钢显微组织和强韧性的影响,并叙述了相应的机制。热轧、析出、再结晶、相变、冷变形和时效的巧妙复合的特殊热处理工艺使10Ni-18Co-12Mo-Ti钢的抗拉强度达4292MPa。