Changes of Tempering Microstructure and Properties of Fe-Cr-V-Ni-Mn-C Cast Alloys

The changes of tempering microstructure and properties of Fe-Cr-V-Ni-Mn-C cast alloys with martensite matrix and much retained austenite are studied. The results showed that when tempering at 200℃ the amount of retained austenite in the alloys is so much that is nearly to as-cast, and a lot of retained austenite decomposes when tempering at 350℃ and the retained austenite decomposes almost until tempering at 560℃. When tempering at 600℃, the retained austenite in the alloys all decomposes. At 560℃ the hardness is highest due to secondary hardening. The effect of nickel and manganese on the microstructure and properties of Fe-Cr-V-C cast alloy were also studied. The results show that the Fe-Cr-V-C cast alloy added nickel and manganese can obtain martensite matrix and much retained austenite microstructure, and nickel can also prevent pearlite transformation. With the increasing content of nickel and manganese, the hardness of as-cast alloy will decreases gradually, so one can improve the hardness of alloy by tempering process. When the content of nickel and manganese is 1.3～1.7%, the hardness of secondary hardening is the highest (HRC64). But when the content of nickel and manganese increase continually, the hardness of secondary hardening is low slightly, and the tempering temperature of secondary hardening rises.     

W6Mo5Cr4V2钢激光淬火组织的回火稳定性

对经过常规处理的Ｗ６Ｍｏ５Ｃｒ４Ｖ２钢用ＣＯ２激光器进行激光淬火处理，并对淬火后的试样进行不同温度的回火处理。试验结果表明，激光淬火组织的回火稳定性明显提高，并且“二次硬化”现象显著。借助电子显微镜观察，分析了回火稳定性提高的原因。     

Laser transformation hardening on rod-shaped carbon steel by Gaussian beam

Laser transformation hardening(LTH) is one of the laser surface modification processes. The surface hardening of rod-shaped carbon steel (SM45C) was performed by lathe-based laser composite processor with Gaussian-beam optical head. The LTH characteristics by dominant processes, longitudinal and depth directional hardness distributions and behaviors of phase transformation in hardened zones were examined. Especially, two concepts of circumferential speed and theoretical overlap rate were applied. When laser power increased or circumferential speed decreased, the surface hardening depth gradually increases due to the increased heat input. Moreover, the longitudinal hardness distribution particularly shows periodicity of repetitive increase and decrease, which results from tempering effect by overlap. Finally, the feasibility of laser transformation hardening is verified by using the beam with Gaussian intensity distribution.     

9Cr2Mo冷轧辊用钢的激光淬火试验

采用硬度测试、显微组织和断口分析,对经激光淬火处理后的9Cr2Mo冷轧辊用钢进行了研究.结果表明,与常规淬火相比,9Cr2Mo钢激光淬火后硬度明显提高,但激光淬火搭接区出现硬度值陡降,其原因为搭接区的马氏体组织回火分解;常规淬火处理后的9Cr2Mo钢内有条、块状碳化物,断口为脆性解理断裂特征;而激光淬火后,条块状碳化物溶解或部分溶解,未完全溶解的碳化物细化成球形颗粒,其断口为浅韧窝+脆性准解理的断裂特征.     

Cr12MoV钢宽带激光淬火组织回火稳定性研究

通过对经常规处理后的Cr12MoV钢用CO2激光器进行宽带激光表面淬火,并对淬火后的试样进行不同温度的回火处理。结果表明,激光淬火组织的回火稳定性明显提高,并且＂二次硬化＂现象显著。借助扫描电镜观察,分析了回火稳定性提高的原因。     

AerMet100超高强度钢激光相变硬化研究

对AerMet100超高强度钢进行了激光相变硬化试验,并对淬硬层的显微硬度分布及其物相变化进行了测试与分析.结果表明,激光相变硬化后淬硬层的硬度得到提高,比基体提高了约200 HV0.2;在同样的激光处理工艺条件下,经激光相变硬化后原始状态为淬火态试样的淬硬层的硬度和深度比退火态试样的要高和深;相变硬化后,随着回火时间的延长,逆转变奥氏体含量增多,硬化层硬度降低.     

�ȴ����ն�1Cr4Ni3CuAlSi����֯Ӳ�ȵ�Ӱ��

 研究了不同固溶温度及不同时效温度对新型时效硬化型塑料模具钢1Cr4Ni3CuAlSi显微组织及硬度的影响。结果表明,该钢固溶温度采用850℃-890℃较为合理, 510℃-550℃时效处理可显著提高其硬度值,是由于时效后通过NiAl时效相析出而硬化。     

汽车同步器拨档环激光热处理

对45钢制汽车同步器拨档环分别进行了热喷涂Mo层、激光熔覆、激光淬火和整体淬火 低温回火处理，观察了各种工艺处理后试样的金相组织，测试了表层显微硬度分布，进行了磨损试验。分析结果表明，拨档环激光表面淬火工艺是较为合理的处理工艺。     

LASER HEAT TREATING RESEARCH OF THREE KINDS OF HIGH SPEED STEEL

１．ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｌａｓｅｒｐｈａｓｅｃｈａｎｇｅ－ｈａｒｄｅｎｉｎｇｔｅｃｈｎｏｌｏｇｙｈａｓｂｅｅｎｗｉｄｅｌｙｐａｉｎａｔｔｅｎｔｉｏｎｉｎｔｈｅｗｏｒｌｄｆｒｏｍ１９７０ｓ．Ｉｎｍａｎｙｃｏｕｎｔｒｉｅｓｔｈｅｒｅｓｅａｒｃｈｉｎｇａｎｄａｐｐｌｙｉｎｇｏｆｓｕｃｈａｔｅｃｈｎｏｌｏｇｙｉｓｃａｒｒｉｅｄｏｕｔ．〔１,２〕Ｎｏｗｔｈｅｌａｓｅｒｐｈａｓｅｃｈａｎｇｅｈａｒｄｅｎｉｎｇｔｅｃｈｎｏｌｏｇｙｈａｓｂｅｇａｎｔｏｓｔｅｐｉｎｔｏｔｈｅｓｔａｇｅｏｆｍａｎｕｆａｃ…     

The use of heating by high-frequency current in heat treating thin steel parts

Conclusions A new method of local hardening of thin steel parts with heating by high-frequency current permits mechanization and automation of the hardening process, eliminates tempering of the ends of the blades in a lead bath, straightening, holding in clamps for tempering, and gives 100% control of the hardness.The labor productivity has increased five times and rejects due to cracking have been eliminated.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, p. 51, November, 1969.     

挖掘机轴销断裂失效分析

直径80 mm的45钢轴销,经过调质、中频淬火和回火处理,在使用了1393 h时发生断裂。化学成分分析、断口分析、金相检验和硬度试验结果表明,轴销的断裂是由中频淬火后的回火不充分及磨削工艺不当所致。     

The Kinetics of Phase Transformations During Tempering in Laser Melted High Chromium Cast Steel

The precipitation of secondary carbides in the laser melted high chromium cast steels during tempering at 300-650?°C for 2?h in air furnace was characterized and the present phases was identified, by using transmission electron microscopy. Laser melted high chromium cast steel consists of austenitic dendrites and interdendritic M₂₃C₆ carbides. The austenite has such a strong tempering stability that it remains unchanged at temperature below 400?°C and the secondary hardening phenomenon starts from 450?°C to the maximum value of 672 HV at 560?°C. After tempering at 450?°C fine M₂₃C₆ carbides precipitate from the supersaturated austenite preferentially. In addition, the dislocation lines and slip bands still exist inside the austenite. While tempering at temperature below 560?°C, the secondary hardening simultaneously results from the martensite phase transformation and the precipitation of carbides as well as dislocation strengthening within a refined microstructure. Moreover, the formation of the ferrite matrix and large quality of coarse lamellar M₃C carbides when the samples were tempered at 650?°C contributes to the decrease of hardness.     

高铬冷作模具钢渗碳层的二次硬化特征

以Ｃｒ１２ＭｏＶ为代表的冷作模具钢，经过高温渗碳，油淬和高温回火，其渗层的二次硬化特征与经常规高淬高回处理的相比有一定的差异，主要表现为二次硬化峰值的位置及数值、残留奥氏体量以及高温回火时析出相的种类等。此外，本文不屯经高温渗碳，等温淬火处理的试样的力学性能。     

A study of heat-treated carburized alloyed steels for blanking dies

This paper describes the results of studying the diffusion layer after carburizing alloyed steels 30Kh7MT and 25Kh12M2VFT for the purpose of selecting heat-treatment regimes for blanking die working parts, as well as comparative data for hardness variations in these steels depending on temperatures of carburizing, hardening, and tempering. Carburizing, hardening, and tempering schedules providing the maximum hardness in steel are determined.     

Predictive modeling of laser hardening of AISI5150H steels

This paper presents accurate predictive modeling of the laser hardening process in terms of laser operating parameters and initial microstructure without the need of any experimental data. The model provides the diagrams that are useful for predicting hardness profiles, optimizing practical process parameters and assessing the potential of laser hardening for different steels. It is shown that the hardness and depth of the hardened layer in hypoeutectoid steels (carbon wt%<1) could be predicted from this model with good accuracy.The model combines a three-dimensional transient numerical solution for a rotating cylinder undergoing laser heating by a translating laser beam with a kinetic model describing pearlite dissolution, carbon redistribution in austenite and subsequent transformation to martensite by utilizing the feedback from the CCT diagram. In order to validate the thermal model and assert the accuracy of temperature predictions the temperature was measured using an infrared camera and a good agreement between the predicted and measured temperatures is shown. Results are presented as processing maps, which show how the case depth and hardness depend on input operating parameters. The good agreement between the measured and predicted hardness profiles ascertains the accuracy of the thermal-kinetic model developed for AISI5150H steels.     

3Cr2Mo塑料模具钢预硬化热处理工艺参数的研究

研究了 3Cr2 Mo塑料模具钢预硬化热处理工艺参数 (淬火温度、回火温度、回火时间 )对钢的硬度和冲击韧度的影响 ,得出了使该钢达到最佳预硬化效果的工艺参数。     

Effect of hardening conditions on mechanical properties of high speed steels

Abstract

Hardness and toughness are the main properties determining wear resistance and performance of high speed steel tools. The objective of the present paper was to study the effect of hardening conditions on the toughness of high speed steels, mainly concerning the hardening temperature and cooling rate during quenching. Several conditions were simulated in laboratory and industrial heat treatment furnaces and toughness was evaluated through the static bend test. Under the same tempering condition, the higher the hardening temperature, the higher the attained hardness. The results also point out a compromise situation between hardness and toughness, until 1200°C hardening temperature is reached; for temperatures over this value, the loss in toughness become more accentuated, without a considerable increase in hardness. The present paper also describes the mechanical properties of M2 high speed steel heat treated to lower hardness, necessary in some cold work tooling applications. In this case, hardening at lower temperatures and tempering close to the peak hardness has shown the best results. And lastly, regarding cooling conditions during nitrogen hardening in a vacuum furnace, the results point out that low quenching pressures might reduce the cooling rate and decreases material toughness, but the differences are very small for pressures between 6 and 9 bar.     

Investigations on Heat Treatment of a High-Speed Steel Roll

High-carbon high-speed steels (HSS) are very abrasion-resistant materials primarily due to their high hardness MC-type carbide and high hardness martensitic matrix. The effects of quenching and tempering treatment on the microstructure, mechanical properties, and abrasion resistance of centrifugal casting high-carbon HSS roll were studied. Different microstructures and mechanical properties were obtained after the quenching and tempering temperatures of HSS roll were changed. With air-cooling and sodium silicate solution cooling, when the austenitizing temperature reaches 1273 K, the metallic matrix all transforms into the martensite. Afterwards, the eutectic carbides dissolve into the metallic matrix and their continuous network distribution changes into the broken network. The second hardening temperature of high-carbon HSS roll is around 793 K. No significant changes in tensile strength and elongation percentage are observed unless the tempering temperature is beyond 753 K. The tensile strength increases obviously and the elongation percentage decreases slightly beyond 753 K. However, the tensile strength decreases and the elongation percentage increases when the tempering temperature exceeds 813 K. When the tempering temperature excels 773 K, the impact toughness has a slight decrease. Tempering at 793-813 K, high-carbon HSS roll presents excellent abrasion resistance.     

矿井支护钢调质工艺及应用

介绍了采用多匝线圈感应加热对矿井支护钢进行调质处理的工艺及设备的特点，矿工钢通过调质处理，综合性能大幅度提高，调质后的矿工钢比热轧矿工钢的抗弯强度提高2.5倍，从而可以用小截面的矿工钢代替大截面的矿工钢，适当加大棚距，节省钢材。     

模压式感应淬火和回火技术

综合感应加热淬火和压淬工艺的优点,推出了一种新的模压式感应淬火回火技术。该技术的工艺路线是零件感应加热后直接采用模具压力淬火,然后进行原位感应加热回火,这样使得模具的退出很容易而且几乎没有磨损。该技术的主要装备是拥有模压式淬火装置以及感应加热系统的新型淬火机床。它适用于任何高精度圆环形零件的批量生产,如汽车滑套、齿圈、同步圈、伞齿轮、耦件等。