轧辊用高碳、钒高速钢系合金的热处理

研究了新开发的轧辊用高碳、钒高速钢系合金的淬火、回火热处理及高温硬度。结果表明：其峰值硬度温度较常规高速钢低１５０～２５０℃；随碳含量增加，峰值硬度温度降低；相同碳含量，钒含量增加，峰值硬度温度升高。二次硬化温度约在５５０℃，但二次硬化的峰值硬度差较小，在二次硬化温度二次回火，二次硬化作用消失。随炭含量、钒含量增加，高温硬度增加。根据轧辊辊面硬度要求，高碳钒高速钢的淬火温度为９５０～１０℃，回火温     

钒含量对Cr8Mo2SiV冷作模具钢组织与性能的影响

研究了钒含量(0.28%和0.50%,质量分数,下同)的变化对Cr8Mo2SiV钢组织和性能的影响。结果表明,随着钒含量的增加,一次碳化物尺寸增大,淬火峰值硬度向高温区移动,钒含量0.5%的Cr8Mo2SiV钢的淬火晶粒尺寸明显小于钒含量0.28%的Cr8Mo2SiV钢。经1 040℃淬火、180~520℃回火后,随着钒含量的升高,Cr8Mo2SiV钢的二次硬化峰值硬度以及二次硬化峰之前的回火硬度均明显提高。钒对提高Cr8Mo2SiV钢的淬火温度和二次硬化效应有利。     

冷轧中间辊用半高速钢16Cr5D 的组织和性能

试验研究了20kg中频感应炉冶炼的半高速钢16Cr5D(%:0.50～0.56C,0.36~0.39Mn,0.95~ 1.03Si,5.34～5.68Cr,0.31~0.41Ni,1.00～1.04Mo,0.29～0.30V)的铸态组织以及880～1060℃淬火、200～750 ℃回火后的锻态组织和机械性能。试验结果表明,该钢最佳淬火温度为970～1000℃,在500 ℃回火有明显 的二次硬化,淬回火后具有良好的综合机械性能,是优良的冷轧中间辊材质     

热处理工艺对高速钢轧辊组织和性能的影响

研究了淬火温度、冷却方式、回火温度和回火次数对高速钢轧辊组织和性能的影响.结果表明,油冷条件下,淬火温度低于1050℃,随着温度升高,硬度升高,超过1100℃,硬度反而降低.盐浴冷却(盐冷)和空冷条件下,淬火温度对硬度影响结果相似,但获得最高硬度的淬火温度高于油冷时的淬火温度.回火温度低于350℃,高速钢硬度变化不明显,超过475℃,随回火温度升高,硬度升高,并在525℃达到最高值,继续提高回火温度,硬度降低.二次回火后硬度变化不大,三次回火后,硬度反而降低.空冷高速钢轧辊,淬透性差;油冷高速钢轧辊易出现裂纹;盐冷高速钢轧辊,具有优良的淬透性,不易出现裂纹,辊面硬度高,硬度均匀性好,耐磨性好     

合金工模具钢Fe-M-C淬火马氏体回火的二次硬化研究进展

含W、Mo、V等合金元素的工模具钢Fe-M-C淬火马氏体在500～600℃回火因纳米级简单间隙相M2C和MC碳化物脱溶析出，提高回火马氏体的硬度而出现淬火马氏体回火的二次硬化。当前对淬火马氏体回火二次硬化的研究趋向是利用现代研究方法进一步分析和研究合金马氏体的脱溶贯序，全面得出弥散沉淀物的组成和淬火合金马氏体二次硬化的主体机制，开发出充分利用二次硬化的新型高性能工模具钢。     

RP65冷轧辊钢热处理工艺研究

本试验对超深淬硬层冷轧工作辊钢RP65的热处理工艺进行了研究,弄清了淬火、回火及冷处理工艺对硬度,马氏体形态及残余奥氏体数量的影响规律,为RP65冷轧工作辊的最终热处理提供了制定工艺的依据。     

淬火方式对M42高速钢组织和性能的影响

采用不同淬火方式(沙冷,雾冷,油冷,水冷)处理M42高速钢,通过SEM、AFM、XRD及维氏硬度仪研究不同冷却速率(1~35℃/s)对该合金微观组织与硬度的影响。结果表明,随淬火冷却速率增大:冷却过程中碳化物析出减少,淬火态残余奥氏体量增加;回火马氏体尺寸从150~200 nm减少到30~60 nm,马氏体晶界上二次碳化物析出量增多且尺寸减小;淬火态合金硬度从835 HV降低至788 HV,回火时二次硬化效果更加明显,回火态合金硬度从945 HV升高至1 002 HV,红硬性硬度从856 HV升高至924 HV。     

W9Mo3Cr4V高速钢激光回火的研究

用正交试验优选出ＷＭｏ３Ｃｏ３Ｃｒ４Ｖ高速钢最佳激光回火工艺参数。研究表明，高速钢的激光淬火硬度和二次硬化峤同于常规淬火者，是激光回火的二次硬化值可以达到常规回火的二次硬化值。     

热处理工艺对Cr12MoV钢组织、硬度及耐磨性的影响

本试验研究了不同淬火和回火工艺热处理对Cr12MoV钢组织、硬度和磨损性能的影响。实验结果表明:当在1050~1100℃范围内淬火、520℃回火时,得隐针马氏体+少量残余奥氏体组织,材料硬度与耐磨性均较好;当在1100℃淬火,各温度二次回火硬度均较一次回火高,当在550℃回火时,试验钢实现二次硬化,且残余奥氏体大量转变,硬度和耐磨性达最大值,材料性能最优。     

热处理工艺对高钼高钒高速钢轧辊组织和性能的影响

研究了淬火温度、冷却方式、回火温度和回火次数对高钼、高钒高速钢轧辊组织和性能的影响。结果表明，油冷条件下，淬火温度低于1050℃，随着温度升高，硬度升高，超过1100℃，硬度反而降低。盐浴冷却（盐冷）和空冷条件下，淬火温度对硬度影响结果相似，但获得最高硬度的淬火温度高于油冷时的淬火温度。回火温度低于350℃，高速钢硬度变化不明显，超过475℃，随回火温度升高，硬度升高，并在525oC达到最高值，继续提高回火温度，硬度降低。二次回火后硬度变化不大，三次回火后，硬度反而降低。空冷高速钢轧辊，淬透性差，油冷高速钢轧辊易出现裂纹，盐冷高速钢轧辊，具有优良的淬透性，不易出现裂纹，辊面硬度高，硬度均匀性好，耐磨性好。     

热处理工艺对新型Cr8Mo2VSi和D2冷作模具钢扁钢组织和力学性能的影响

 研究了热处理工艺对高碳、高铬冷作模具钢Cr8Mo2VSi和D2钢的组织和性能的影响,结果表明：Cr8Mo2VSi比D2钢的碳化物更细小、均匀;1020～1040 ℃淬火,Cr8Mo2VSi的硬度略低于D2,经高温回火后,Cr8Mo2VSi钢表现出更好的二次硬化效应,其硬度高于D2钢1~2（HRC）,并且比D2钢具有更好的强、韧性配合。     

Effect of shock-wave treatment on the structure and hardening of austenitic steels

The structure and hardening of austenitic steels subjected to shock-wave treatment have been studied. This treatment is shown to form a structure whose cell size decreases with increasing pressure. The treatment-induced hardening of the steels can be estimated using the Hall-Petch relation. At the same degrees of residual deformation, shock-wave treatment results in a significantly higher degree of hardening of the austenitic steels as compared to cold rolling. The degree of hardening increases with decreasing stacking-fault energy in austenite.     

半高速钢冷轧辊材料的锻后淬火工艺

 研究了半高速钢冷轧辊材料的锻热淬火工艺,并与传统热处理工艺获得的力学性能和微观组织进行比较评价,得到如下结论：半高速钢冷轧辊材料锻热淬火（终锻温度大于等于900℃、油冷）+750℃回火后的碳化物尺寸适中,分布均匀弥散,细小的碳化物在最终热处理时容易固溶,对最终热处理组织较为有利;新工艺轧辊的强度、塑性和冲击韧性介于球化退火和调质热处理之间,有着比较均衡的强韧性,而且硬度适中,易于机械加工。因此,新的锻热淬火工艺可以代替传统的锻后热处理工艺,达到节能降耗、提高生产效率的目的。     

Alloying Elements in High Speed Steels

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Effect of Nitrogen and Niobium on the Structure and Secondary Hardening of Super Hard High Speed Tool Steel

High‐speed steels have been used mostly for multi‐point cutting tools and for plastic working tools. High speed steels are ferrous based alloys of the Fe‐C‐X multi‐component system where X represents a group of alloying elements comprising mainly Cr, W or Mo, V, and Co. The properties of these steels can be improved by modifying their chemical composition or the technology of their production. One of the new trends in modifying the tool steels chemical composition consists in the addition of niobium and nitrogen. In this work, the effects of niobium and nitrogen on morphology of carbides and secondary hardening temperature of investigated high speed tool steels were studied. This experimental work shows that, the conventional ingots have many types of carbides of different shapes and sizes precipitate on the boundary together with thick needle like carbides. On the contrary, for nitrogen steel, the nitrogen alloying leads to form dense, fine and well distributed microstructure. While, on the case of niobium alloying, single carbide (MC), and different types of eutectic carbides were precipitated which have a major effect on the secondary hardening temperature.     

Design of strong tough Fe/Mo/C martensitic steels and the effects of cobalt

The microstructures and mechanical properties of a series of vacuum melted Fe/(2 to 4) Mo/(0.2 to 0.4) C steels with and without cobalt have been investigated in the as-quenched fully martensitic condition and after quenching and tempering for 1 h at 673 K (400°C) and 873 K (600°C); austenitizing was done at 1473 K (1200°C) in argon. Very good strength and toughness properties were obtained with the Fe/2 Mo/0.4 C alloy in the as-quenched martensitic condition and this is attributed mainly to the absence of internal twinning. The slightly inferior toughness properties compared to Fe/Cr/C steels is attributed to the absence of interlath retained austenite. The two 0.4 pct carbon steels having low Mo contents had approximately one-half the amount of transformation twinning associated with the two 0.4 pct carbon steels having high Mo contents. The plane strain fracture toughness of the steels with less twinning was markedly superior to the toughness of those steels with similar alloy chemistry which had more heavily twinned microstructures. Experiments showed that additions of Co to a given Fe/Mo/C steel raised M_s but did not decrease twinning nor improve toughness. Molybdenum carbide particles were found in all specimens tempered at 673 K (400°C). The Fe/Mo/C system exhibits secondary hardening after tempering at 873 K (600°C). The precipitate is probably Mo₂C. This secondary hardening is associated with a reduction in toughness. Additions of Co to Fe/Mo/C steels inhibited or eliminated the secondary hardening effect normally observed. Toughness, however, did not improve and in fact decreased with Co additions.     

Effects of alloying additions and austenitizing treatments on secondary hardening and fracture behavior for martensitic steels containing both Mo and W

The effects of alloying additions and austenitizing treatments on secondary hardening and fracture behavior of martensitic steels containing both Mo and W were investigated. The secondary hardening response and properties of these steels are dependent on the composition and distribution of the carbides formed during aging (tempering) of the martensite, as modified by alloying additions and austenitizing treatments. The precipitates responsible for secondary hardening are M₂C carbides formed during the dissolution of the cementite (M₃C). The Mo-W steel showed moderately strong secondary hardening and delayed overaging due to the combined effects of Mo and W. The addition of Cr removed secondary hardening by the stabilization of cementite, which inhibited the formation of M₂C carbides. The elements Co and Ni, particularly in combination, strongly increased secondary hardening. Additions of Ni promoted the dissolution of cementite and provided carbon for the formation of M₂C carbide, while Co increased the nucleation rate of M₂C carbide. Fracture behavior is interpreted in terms of the presence of impurities and coarse cementite at the grain boundaries and the variation in matrix strength associated with the formation of M₂C carbides. For the Mo-W-Cr-Co-Ni steel, the double-austenitizing at the relatively low temperatures of 899 to 816 °C accelerated the aging kinetics because the ratio of Cr/(Mo + W) increased in the matrix due to the presence of undissolved carbides containing considerably larger concentrations of (Mo + W). The undissolved carbides reduced the impact toughness for aging temperatures up to 510 °C, prior to the large decrease in hardness that occurred on aging at higher temperatures.