硅对低合金高速钢二次硬化的影响

本文系统地研究了钢中硅含量的变化(0.2～3.5％)对(WMo2Cr_4VSi钢二次硬化的影响,探讨了硅影响二次硬化的机理。结果和分析表明:硅可以降低二次硬化峰值温度10～70℃,提高二次硬度1～3HRC;其原因是硅降低了特殊碳化物在回火时的析出温度,细化了回火析出的特殊碳化物并增加其析出量。硅对钢的抗回火稳定性不利,但并不降低温度低子600℃时的红硬性,     

回火温度对16Co14Ni10Cr2Mo钢断裂韧度和抗应力腐蚀性能的影响

研究了回火温度对１６Ｃｏ１４Ｎｉ１０Ｃｒｔ２Ｍｏ钢断裂韧度ＫＩＣ和抗应力腐蚀性能ＫＩＳＣＣ的影响。发现５１０℃以下回火ＫＩＣ和冲击值ａｋ的变化一致，都表面出回火马氏体脆性，但在回火脆性区内ＫＩＣ不降低。在二次硬化峰之前ＫＩＳＣＣ值很低，这是二次硬化钢不能在硬化峰之前回火使用的重要原因。     

热处理温度对3Cr2W8V钢的韧性及断裂行为的影响

3Cr2W8V钢具有高温回火脆性,断裂韧性的谷值与二次硬化峰相对应,冲击韧性的谷值较二次硬化峰高出50～100℃。淬火温度自1200℃以上,经650℃以上回火后,断裂方式由穿晶转为沿晶,认为是1200℃以上高温淬火后,大量钨溶入基体,使高温回火时沿原奥氏体晶界析出M6C所致。     

热处理对粉末冶金高速钢T15碳化物的影响

碳化物是高速钢组织的重要组成部分,其种类和数量对钢的力学性能有重要的影响。本文通过采用物理化学电解法提取碳化物,用SEM对碳化物的形貌进行观察,分别用EDS、XRD测定碳化物的成分和结构,并研究了碳化物对硬度的影响。结果表明：退火态的碳化物质量百分数为28．1％,淬火态的为18．4％,而回火态的质量百分数为24．8％,回火态碳化物扫描照片有明显的二次析出相,产生了二次硬化现象,硬度明显升高。     

回火温度对16Col4Ni10Cr2Mo钢断裂韧度和抗应力腐蚀性能的影响

研究了回火温度对１６Ｃｏｌ４Ｎｉｌ０Ｃｒ２Ｍｏ钢断裂韧度Ｋ_（ＩＣ）和抗应力腐蚀性能Ｋ_（ＩＳＣＣ）的影响。发现５１０℃以下回火Ｋ_（ＩＣ）和冲击值ａ_ｋ的变化一致，都表现出回火马氏体脆性，但在回火脆性区内Ｋ_（ＩＣ）不降低。在二次硬化峰之前Ｋ_（ＩＳＣＣ）值很低，这是二次硬化钢不能在硬化峰之前回火使用的重要原因。     

二次硬化超高强度钢组织与性能EI

研究了回火温度对１６ＮｉＣｏ和２３ＮｉＣｏ二次硬化超高强度钢显微组织与力学性能的影响。二次硬化峰的形成是具有稳定高密度位错的马氏体及自基体共格析出的Ｍ２Ｃ共同作用的结果。在４３０℃回火出现的韧性降低，与板条间形成的渗碳体有关。     

Cr-W-Mo-V高合金高碳钢的二次硬化特性及回火硬度计算

Cr-W-Mo-V高合金高碳钢高温回火时的二次硬化有两种形式，其一是最高回火硬度对应着一定的淬火温度和回火温度，且回火温度随淬火温度升高而升高；其二是最高回火硬度随淬火温度升高而升高，但回火温度基本不变。二次硬化的回火温度和最高回火硬度既与各类型碳化物沉淀的热力学和动力学有关，亦与残余奥氏体转变的进程有关，归根结底由淬火加热时的奥氏体基体成分决定的。依据奥氏体化温度下基体成分，提出基体成分配比碳公式为Cp=0、011W＋0．02Mo＋0．057Cr＋0．19V，二次硬化的回火硬度的计算公式为Hc=a（1＋b）／（0．0127a＋0．00267），其中a为基体碳饱和度，b为碳化物沉淀量的修正因子。     

低合金高速钢回火过程的电镜研究(二)——M_3C碳化物的沉淀及其转化

低合金高速钢w3M02Cr4VSi在回火过程中要析出一系列碳化物。作者在文献~([1])中研究了特殊碳化物的沉淀过程,发现盘状的MC型碳化物对二次硬化起主要作用。本文通过透射电镜对M_3C渗碳体的沉淀及其转化进行了较系统的研究。     

7Cr7mO2v2Si钢的回火与二次硬化

研究了７Ｃｒ７ＭｏＶ２Ｓｉ钢回火时相及组织的力学性能的变化规律，着重观察了二次硬化峰值附近碳化物的结构和形貌。结果表明，该钢的二次硬化主要是ｆｃｃ结构的Ｖ４Ｃ３及Ｍｏ２Ｃ呈圆盘状宙淀所致。     

高速钢中马氏体回火过程的x射线研究

用三指数不等的晶面族衍射峰的重心法测定了6—5—4—2高速钢经淬火和180—650℃多次回火后马氏体(α′—相)的正方度;发现低温回火析出碳使正方度下降之后,450℃以上α′—相的c/α比值重新升高,在500—520℃达到极大值。x射线定相分析得出,330℃至45O℃范围内析出了M_3C,但到500℃消失,直到600℃以上回火才能明确判定标志合金碳化物(MC)的衍射峰之出现。在520—600℃,{110}α′峰出现不对称的边带。讨论了上述现象的原因及对研究高合金马氏体二次硬化的意义。     

20CrV钢机用锯条齿部表面强化组织的研究

本文介绍了２０ＣｒＶ钢机用锯条经渗金属、渗碳、淬火及回火的表面强化处理工艺，并对强化后锯条齿部碳化物、相结构进行了组织分析和Ｘ射线检测。研究结果表明，齿部组织状态及相结构已接近高速钢，经切削试验，性能达到高速钢要求。     

Laser surface hardening of AISI 01 tool steel and its microstructure

Abstract

The effects of laser surface hardening on AISI 01 tool steel samples were studied by changing the laser operating parameter combinations and the initial steel microstructure. Both melted and solid state transformed regions were produced, and then studied using optical microscopy, analytical electron microscopy, X-ray diffraction, and measurements of micro hardness to investigate the hardening mechanisms and the development of compressive residual stresses. The results indicate that hardened case depths up to 0·6 mm can be obtained using a laser beam operated at a power of 500 W and a scan rate of 2·1 mm s^?1, but that different amounts of retained austenite and undissolved carbides are observed for different beam powers. Quenched and tempered AISI 01 steel samples, with initial hardness values in the range 30–40 HRC, are better suited for laser surface hardening compared with the samples with initial hardness of 48–50 HRC, because the formation of an over tempered region adjacent to the hardened zone can be avoided.

MST/901     

Entfestigungsverhalten des Stahls 50 CrV4 bei der thermomechanischen Behandlung

Softening behaviour of 50 CrV4 steel on thermomechanical treatment Determination of static softening of austenite on thermomechanical treatment of steel by rolling. Analysed was the development of the austenite structure and influencing the work softening processes depending on the deformation-temperature-time mode. The static softening processes were modelled mathematically by using Avrami's relationships.     

Metallographic study of non-homogenous armour impacted by armour-piercing incendiary ammunition

In this paper, the influence of impact and incendiary effect on the microstructure changes and crack development in non-homogenous add-on armour is studied. The main objective was to determine the parameters that may cause the yielding of the material, leading to a possible decrease in multi-hit resistance. For that purpose, patented wire fence and perforated plates made from two types of high strength steel, Hardox 450 and 50CrV4 tempered at 170 °C were tested. Various techniques were applied: high speed video camera was used, visual macroanalysis, light microscopy, scanning electron microscopy and energy dispersive X-ray analysis. It was found that incendiary effect, being of a brief nature, does not have any influence on microstructure of the add-on armour. However, impact greatly influences crack development and propagation, which occurs in 50CrV4 steel, the material with lower ductility, diminishing its multi-hit resistance. In accordance with obtained results, non-homogenous add-on armour behaviour models were devised, describing the influence of material ductility and geometry on fracture mode, stresses and deformability.     

基体对高锰钢辙叉爆炸硬化效果的影响

为了研究基体对高锰钢辙叉爆炸硬化效果的影响,使用厚度3mm、密度1.38g/cm3的板状炸药分别在50mm厚钢板上、空气中及沙土上对高锰钢辙叉试件进行爆炸硬化。试验结果表明,在钢板上、空气中和沙土上对高锰钢进行爆炸硬化后,高锰钢辙叉试件的硬度分别提高了85.1%、76.6%和82.6%。与在钢板上和空气中相比,在沙土上对高锰钢辙叉试件进行爆炸硬化既能保证硬化后辙叉试件的硬度≥350HB,又能保证辙叉试件的整体不发生严重的变形。     

On the microstructure and mechanical properties of high-speed steels

The microstructure of high-speed steels consists of a martensitic matrix with a dispersion of two sets of carbides. These carbides are usually known as primary and secondary carbides. The role of the primary carbides has been reported to be of no importance in strengthening the steels, due to their large size and large interparticle spacing. The present authors have studied the role of the primary carbides on the wear of high-speed steels and found them to be of no importance, and under certain conditions contributing to higher wear rates. It has been shown analytically and experimentally that in quenched and tempered high-speed steels, the precipitation of the secondary hardening carbide (cubic M₂C type) is the main reason for the improved strength and wear resistance. This shows that the secondary hardening phenomenon of high-speed steels is a direct result of the hardening caused by the precipitation of the cubic M_2C-type carbide. The present study has estimated that at peak hardness the volume fraction of secondary hardening carbides is approximately 20%. The measured strength of high-speed steels was found to be lower than the theoretically calculated strength due to non-homogeneous precipitation of the secondary hardening carbides. Areas which were observed to be free from secondary hardening carbides are real and are not artefacts. It has been shown that the strength of high-speed steel in the region of peak hardness depends primarily on the precipitation of the secondary hardening carbide and secondarily on martensitic strengthening.     

高锰钢整铸辙叉爆炸硬化实践与研究

针对目前爆炸硬化所用炸药的性能不足,研制出一种高聚物粘结塑性炸药,利用该塑性炸药对高锰钢辙叉进行爆炸硬化。试验表明,经过该炸药表面硬化后的高锰钢辙叉,在铸造基体硬度为HB170～190时,一次硬化后,表面硬度达到HB260—280;两次硬化后,表面硬度达到HB310～330。并进一步结合金相分析,探讨当前国内在高锰钢爆炸硬化中硬度测量方面存在的问题。最后,运用动力有限元软件对高锰钢爆炸硬化工艺过程进行了数值模拟,模拟结果与实验情况基本吻合。     

M2高速钢插齿刀激光熔凝强化层与刀刃显微硬度关系的调控研究

研究了M2（W6Mo5Cr4V2）高速钢经激光熔凝淬火和570℃一次回火处理前后的强化层硬度变化和表面粗糙度,并对M2高速钢插齿刀的激光熔凝淬火加工部位进行了分析优化,讨论了刀具经激光强化及精加工后刀刃部位的显微硬度变化规律。试验研究表明：经过不同工艺参数组合的激光熔凝淬火后,试样得到不同的表面硬度,再经过一次回火后,试样表面具有明显的二次强化效应,且粗糙度值较稳定;插齿刀前刀面刀刃部位显微硬度变化规律具有工程适用性,为优选出最佳激光工艺参数及工艺方法提供了实验依据。     

Influence of alloying and secondary annealing on anneal hardening effect at sintered copper alloys

This paper reports results of investigation carried out on sintered copper alloys (Cu, 8 at%; Zn, Ni, Al and Cu-Au with 4 at%Au). The alloys were subjected to cold rolling (30, 50 and 70%) and annealed isochronally up to recrystallization temperature. Changes in hardness and electrical conductivity were followed in order to investigate the anneal hardening effect. This effect was observed after secondary annealing also. Au and Al have been found to be more effective in inducing anneal hardening effect.