共查询到20条相似文献,搜索用时 31 毫秒
1.
应用炼钢过程中夹杂物控制的热力学模型预测钢包精炼和钢液凝固后钢中氧化物夹杂的成分,在模型预测指导下进行了自润滑易切削钢工业生产试验,并对开发的易切削钢进行了切削性能测试。结果表明,钢中氧化物夹杂预测结果与实测结果一致;用无涂层P10刀具进行的切削试验结果也表明,与传统含铅易切削钢相比,自润滑易切削钢在高速(v≥200 m/min)切削条件下,后刀面磨损降低200%;切削速度v=100 m/min时,二者相当;v=200 m/min时,前刀面月牙洼磨损降低200%,且月牙洼离刀刃较远。说明在高速切削条件下,开发的新一代自润滑易切削钢的切削性能明显优于传统含铅易切削钢,完全可替代传统含铅易切削钢。 相似文献
2.
《钢铁冶炼》2013,40(5):333-338
AbstractHistorical analysis of metal cutting shows that metal removal rates have been increasing in the course of the century, predicated by the advancement in tool materials but the steel design has lagged behind. This paper examines the mechanisms of chip formation and tool wear as a function of cutting speed in metal cutting. Chemical wear is identified as the dominant mechanism of tool wear at high cutting speeds caused by temperature rise due to shear localisation in the primary and secondary shear zones of chip. Shear localisation in the primary shear zone is shown to be influenced by both microstructural parameters, i.e. matrix hardening and second phase particles, and metal cutting variables, i.e. cutting speed (strain rate) and feed (pressure). Shear localisation in the secondary shear zone is caused by the tribological conditions of seizure at the tool/chip interface. Chemical crater wear is caused by the dissolution of tool into the workpiece (chip) by diffusion mechanism and can be prevented by suppressing the tribological condition of seizure. The design of steel for high speed machining is based on engineering glassy oxide inclusions in steel, which are designed to form a viscous layer in situ at the tool/chip interface at high cutting speeds. The viscous layer lubricates the tool/chip interface and prevents the occurrence of seizure, thereby suppressing chemical crater wear. In comparison with the large volume fraction of inclusions required for promoting ductile fracture at low cutting speeds, the amount of inclusions required for lubricating the tool/chip interface is very small and is in the range that is typical of clean steel. Thermodynamic modelling is shown to be a powerful tool to engineer glassy oxide inclusions in steel 相似文献
3.
4.
开展了向中碳45结构钢中加入S、Ca元素来改善切削性的研究。研究结果表明:钢中w([S])=0.06%,总钙w(T[Ca])=40×10-6,w([Al]s)=0.01%左右时,夹杂物的纺锤率为57%;小于2.5 μm的夹杂物数量占夹杂物总数82%,夹杂物呈细小、弥散状态分布于钢中。由热模拟试验得出钢的塑性转变温度在1100~1000 ℃,通过配水软件计算出二冷各区的冷却水流量并应用于生产,铸坯表面和内部无裂纹,力学性能与未加S、Ca元素的45钢相当,但切削性能有明显的改善,切削刀具寿命提高了25%以上。 相似文献
5.
The effect of total oxygen content on the machinability of low carbon resulfurized free cutting steel was studied by means of machinability tests, metallographic, and scanning electron microscopy observation. The results showed that the total oxygen content had a notable effect on the machinability of SAE 1215 steel. The best machinability of the steel in terms of tool life and surface roughness could be obtained by controlling the total oxygen content at 0.0105 and 0.0125 wt%. When total oxygen content in the steel was less than 0.0105 wt%, the machinability of the steel was increased with the increase of total oxygen content because of the significant reduction of the aspect ratio of MnS inclusions. However, when total oxygen content in the steel was more than 0.0125 wt%, the machinability of the steel was deteriorated dramatically with the increase of total oxygen content, which was attributed to that the amount and the size of oxide inclusions (MnO–Al2O3, MnO–SiO2, and 2MnO–SiO2) with high hardness and high melting point both had a significant increase, and some MnS inclusions were also wrapped by the MnO–SiO2 and 2MnO–SiO2 hard oxides. Furthermore, the tool wear would reach the maximum when total oxygen in the steel rose to 0.0150 wt%. 相似文献
6.
Low levels of lead are added to free cutting steels to improve machinability. For environmental reasons, there is interest in alternatives to lead that are technically and commercially viable. The machining performance of eight low carbon free cutting steels with alternative machinability enhancers, including additions of bismuth, increased sulphur (with and without tellurium), tin and phosphorus, has been investigated. In tests with high speed steel tools and lubricant, the leaded steel showed the best performance in terms of production rate, surface finish and chip form. In tests with coated carbide tools at a range of cutting speeds the standard non‐leaded 11 SMn30 steel performed well in terms of tool wear, but showed poorer chip form than the leaded steel. The steels with increased sulphur showed improved performance compared with the 11SMn30 steel in tests using high speed steel tools and lubricant, but did not approach the leaded steel in terms of production rate. The steels containing tin did not generally perform better than the 11 SMn30 steel. The 11 SMn30Bi steel gave performance approaching that of the leaded steel in tests with high speed steel tools and lubricant. However, the cost of this addition may make it uneconomic for large scale use. 相似文献
7.
齿轮钢广泛应用于汽车、机械等传动系统,易切削化是提高齿轮加工效率、降低制造成本的主要途径之一。提高钢中硫元素含量是改善齿轮钢切削性能的有效方式,然而过多的硫元素在轧制时会形成条带状MnS,增大钢的各向异性,因此需要对硫化物进行改制处理。分别采用Ca处理和Mg处理两种方式对20MnCr5齿轮钢进行硫化物改质,通过对力学性能、组织形态、夹杂物分布以及切削性能等表征,对比分析不同改制方式对材料的影响。结果表明,Ca处理和Mg处理后试验钢的强度和塑性保持一致,而Mg处理试样的晶粒尺寸较小,因而韧性较高。Ca处理试验钢中MnS夹杂物数量较多,长条状夹杂物比例相对较高;而采用Mg处理可以有效降低钢中夹杂物的数量,夹杂物平均尺寸有所增大,同时小长径比夹杂物数量增多,但是复合氧化物型夹杂物的数量也有所增加。在240~280 m/min条件下进行了干切削试验,结果表明两种试验钢均出现前刀面磨损、后刀面磨损和边界磨损,其中Ca处理试样的刀具磨损较为严重,同时在较高切削速度下出现了积屑瘤和崩角现象,而Mg处理试样则具有更长的刀具使用寿命,对切削速度的敏感性也较低。分析可知,Mg处理后钢中存在较多的大尺寸球状硫化物夹杂物,提高了应力集中效应,更有利于改善切削性能,因而改制效果更好。 相似文献
8.
添加铜、硫可以明显提高高铬钢的机械加工性能,且铜、硫对高铬钢的机械加工性能的作用类似.通过高分辨透镜(HREM)和扫描电镜(SEM)对含铜高铬钢中的易切削相进行分析.研究发现,含铜高铬钢中的易切削相是大小为10 nm左右的石墨-铜复合相,该相均匀弥散地分布于含铜高铬钢基体中,该相中76.07%的原子是石墨碳,其余则为铜原子.在机械加工时,石墨-铜复合相的固体润滑膜能够附着在刀具的切削刃上,从而避免了含铜高铬钢与切削刃的直接接触,从而减少了切削刃的磨损,改善了高铬钢的切削性能. 相似文献
9.
汽车曲轴用钢42CrMo要求在不影响力学性能的前提下,具有较好的切削性。传统的钢种无法满足使用需求,通过在钢中添加B、N元素,并对钢中夹杂物进行控制,以满足性能要求。首先通过坩埚熔炼实验得到不同B、N含量的试样;其次利用FactSage软件计算出理想条件下不同B、N含量的钢液中各种夹杂物的析出量及析出温度;然后通过对试样设置不同的冷却方式和定向凝固实验,得到钢中BN夹杂物的形貌、尺寸及分布的影响因素;最后,通过切削实验研究了夹杂物对切削性能的影响因素,最终得到理想切削性能的BN型易切削钢。结果表明,尺寸较小而密度较大的BN夹杂物对钢的切削性能的改善作用更好。切削性较好的试样,其切削性能已达到与硫系易切削钢Y1215同等水平。 相似文献
10.
The inclusions formed in experimental steels by calcium, aluminum, and silicon additions are characterized. The morphology,
phase identity, elemental analyses, and semiquantitative wt pct of the inclusions in each steel are presented. A correlation
of tool wear tests conducted on the experimental steels and the inclusion characteristics indicates that a major factor in
tool flank wear is the high temperature hardness of the inclusion phases or inclusion abrasion. A steel containing glass-like
inclusions produced minimal tool wear but when the inclusions were a crystalline silicate, tool wear increased. The most severe
tool wear occurred when machining steels with CaO·6Al2O3, Al2O3, and/or AIN as the major inclusion phases. By judicious selection of the deoxidation practice, the formation of refractory
type oxide inclusions may be prevented and inclusions that enhance machinability may be formed.
GLORIA M. FAULRING, formerly Graduate Student, State University of N.Y. at Buffalo 相似文献
11.
Laizhu Jiang Hannu HÄnninen Jukka Paro Veijo Kauppinen 《Metallurgical and Materials Transactions A》1996,27(9):2796-2808
In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools
when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated.
Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life
of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively.
Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining
powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range,
from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated
cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated
high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L
steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L
steel was longer than that when machining 2205 steel.
formerly with the Laboratory of Engineering Materials, Helsinki University of Technology 相似文献
12.
在不同切削速度(200~230 m/min)和切削深度(0.5~2 mm)下试验研究了普通20CrMnTiH齿轮钢(0.006%S)和含硫20CrMnTiH齿轮钢(0.031%S)的切削性能。结果表明,随切削速度增大,刀具的磨损增大,在200 m/min,0.031%S钢是0.006%S钢刀具的使用寿命的2.8倍;在230 m/min,0.031%S钢是0.006%S钢刀具使用寿命的2.6倍;随切削深度增加,切削力增加,但在相同切削深度下,0.031%S钢的切削力低于普通0.006%S钢;由于0.031%S钢存在≤6μm的MnS夹杂,使切屑易断,并硫化物夹杂能够包裹Al2O3尖晶石夹杂,减少刀具磨损,提高钢材的切削性能。 相似文献
13.
14.
15.
16.
对现场和实验室冶炼的8炉低碳高硫易切削钢进行切削试验,同时对钢中的非金属夹杂物进行评级和SEM及DES能谱分析。结果表明:无论钢中是否含有锡等易切削元素,低碳高硫易切削钢的刀具磨损量均随钢中B+C类氧化物夹杂级别的增高而明显增加;钢中存在的氧化物夹杂主要为硬质Al2O3-MnO和MnO-SiO2、2MnO-SiO2型氧化物,可加剧切削过程的刀具磨损。钢中氧含量和氧化物夹杂级别相对较低时,适当提高氧含量可促使有利形态的MnS生成而使可切削性能得到改善;当氧含量高时,钢中氧化物夹杂级别明显提高,从而导致可切削性能的明显恶化。 相似文献
17.
LI Zhuang 《钢铁研究学报(英文版)》2010,17(1):59-63
In the present paper, the machinability tests were conducted by using various processing parameters on a CA6164 lathe with a dynamometer. The metallurgical properties, machinability and mechanical properties of the developed alloy were compared with those of an austenite stainless steel 1Cr-18Ni-9Ti. The results have shown that the machinability of the austenitic stainless steels with free-cutting additives is much better than that of 1Cr-18Ni-9Ti. This is attributed to the present of machinable additives. The inclusions might be composed of MnS. Sulfur and copper addition contributes to the improvement of the machinability of austenitic stainless steel. Bismuth is an important factor to improve the machinability of austenitic stainless steel, and it has a distinct advantage over lead. The mechanical properties of the free cutting austenitic stainless steel are similar to that of 1Cr-18Ni-9Ti. A new Pb-free austenitic stainless steel with high machinability as well as satisfactory mechanical properties has been developed. 相似文献
18.
19.