色呦呦网址在线观看,久久久久久久久福利精品,国产欧美1区2区3区,国产日韩av一区二区在线

Cemented carbide(hardmetal) is a general term for alloys composed of carbides, nitrides, borides, or silicides of high melting point metals (W, Mo, Ti, V, Ta, etc.). Divided into two major categories of casting and sintering. The cast alloy has high brittleness and low toughness, and has little practical application value. Widely used are sintered alloys, which are generally sintered from tungsten carbide or titanium carbide and cobalt powder and have high hardness, wear resistance and hot hardness. Mainly used to manufacture high-speed cutting and processing of hard materials, in recent years, the use of carbide in the mold industry is also increasing, so it is of practical significance to discuss and study the hard alloy heat treatment.

1. Features of Cemented Carbide

Carbide is made by the method of powder metallurgy from the refractory metal hard compound and the metal bonding phase. The commonly used hard compounds are carbides. As the hard alloy for cutting tools, commonly used WC, TiC , TaC, NbC, etc., the binder is Co, and the strength of the cemented carbide mainly depends on the content of Co. Because the carbide in the cemented carbide has a high melting point (such as a melting point of 3140° C. of Ti C), a high hardness (such as a hardness of 3200 HV of TiC), a good chemical stability, and a good thermal stability, the hardness and wear resistance thereof are high. Sex and chemical stability are much higher than high-speed tool steels.
The commonly used cemented carbide hard phase is mainly WC, which has good wear resistance. Although some carbides have similar hardness as WC, they do not have the same wear resistance. WC has a higher yield strength (6000 MPa), so it is more resistant to plastic deformation. WC’s thermal conductivity is also good, and thermal conductivity is an important performance index of the tooling. WC has a lower coefficient of thermal expansion, about 1/3 of that of steel; its modulus of elasticity is 3 times that of steel, and its compressive strength is also higher than that of steel. In addition, WC has good resistance to corrosion and oxidation at room temperature, good electrical resistance, and high bending strength.

Heat Treatment of Tungsten Carbide Products 1

Fig.1 The quasi-equilibrium diagram of WC-Co alloy

2. Heat treatment and alloy organization

It has been studied on the bonding phases of WC-Co alloys with different C/W ratios of 5% to 35% WC. The conclusions are drawn as follows: γ-phase or (γ+WC) phases are generated in the alloy at slow cooling; When there are (γ+η) phases appear. However, since the (γ+η) phase is unstable, the (γ+η) phase will transform into a stable (γ+WC) phase after annealing. According to the test results, the quasi-equilibrium phase diagram shown in Fig. 1 is drawn (the solid line is the phase diagram of the stable system, and the dashed line is the local phase diagram illustrating the η characteristics of the quasi-stable phase).
The annealing (slow cooling) of the typical cemented carbide depends mainly on the carbon content: when C/W>1, the free carbon precipitates on the WC-Co phase boundary; when the C/W<1, the microstructure of the alloy has In both cases: One is in the three-phase region (WC + γ + η). It is inevitable that the η phase appears after the alloy is slowly cooled. If such a large amount of η phase exists in the cementitious phase, branched crystal grains appear, and the small grains are unevenly distributed; if there is a large grain of η phase, the grains are separated by a long distance, so there is information that the η phase is Higher temperatures have begun to form.
In the other case, when the alloy is in the two-phase (WC+γ) region, the W alloy will be precipitated as Co3W from the bonding phase after the low-carbon alloy is annealed. The reaction process can be expressed by the following formula. Co Face-centered cubic → Co Face-centered cubic + Co3W Therefore, this low-carbon two-phase WC-Co alloy will be transformed into a three-phase (WC + γ + CoW) structure after annealing. Figure 2 shows the dissolution curves of W for two-phase WC-Co alloys at different annealing temperatures. The curve is the critical temperature curve for two-phase alloys transformed into three-phase (WC+γ+CoW) alloys: above the curve temperature Annealing results in a two-phase microstructure alloy; annealing at temperatures below the curve yields a three-phase structure containing Co3W.

3. Effect of heat treatment process on mechanical properties of hardness alloy

(1) Effect on Strength Since WC has different solid solubility at different temperatures in Co, it provides the possibility of precipitation hardening of the binder phase by solid solution temperature quenching and subsequent aging. Quenching can inhibit the precipitation of WC and the homotropy transition of Co (Co dense hexagonal, Co face centered cubic). It has been reported that the strength of the alloy containing 40% cobalt can be increased by about 10% after quenching, but the strength of the alloy containing 10% cobalt is reduced after quenching. Considering that the amount of cobalt contained in cemented carbides commonly used in engineering is generally 10% to 37%, the effect of heat treatment on the alloy strength is very small. So someone dared to assert that quenching is not a way to increase strength for W-Co alloys. Annealing also causes a decrease in the strength of the alloy, as shown in Tables 1 and 3. The properties of tungsten carbide vary with the amount of Co contained and the thickness of the grains, as shown in Figure 4.

Heat Treatment of Tungsten Carbide Products 2

Fig. 2 The solid solubility curve of tungsten in WC-10%Co two-phase alloy

Heat Treatment of Tungsten Carbide Products 3

Fig.3 Effect of annealing at 800°C on the flexural strength of WC-10%Co content

Table 1 Effect of annealing at 650 °C on bending strength of WC-11% Co alloy
(2) Effect on Hardness When WC-Co alloy ages, Co3WCX and Co3WCX precipitate in dense tissue phase, so the hardness of the alloy will increase, but the hardness of the alloy will decrease when it is subsequently converted to Co3W. The H.Jonsson test data is shown in Figure 5 and Figure 6. Although the existence of Co3WCX after heat treatment slightly improves the hardness of the alloy, considering the longer heat treatment time and lowering of the flexural strength, it is thought that the precipitation of Co3WCX phase to make the binder phase disperse and harden is not an effective method for the development of new grades. Another way should be found. .
(3) The typical heat treatment of cemented carbide is shown in Table 2.

Table 2 typical heat treatment process of hard alloy

Heat Treatment of Tungsten Carbide Products 4

Figure 4 The properties of WC cemented carbide vary with the amount of Co and grain size

Heat Treatment of Tungsten Carbide Products 5

Fig. 5 Relationship between hardness and aging time of WC-Co alloy binder phase

Heat Treatment of Tungsten Carbide Products 6

Fig. 6 Relationship between hardness and aging time of WC-Co alloy

4. Hard alloy coating

In order to further improve the wear resistance of the hard alloy, a hard material such as TiC or TiN may be vapor-deposited on the surface thereof. The coating material should meet the following requirements:
1 It should have high hardness at low temperature and high temperature.
2 has good chemical stability.
3 should have permeability and no air hole.
4 The material to be processed should have a low friction factor.
5 To bond firmly with the tool body. 6 It is economical and easy to produce. In today’s world, cemented carbide is also the main material of cutting tools. It is also expanding its application share in molds, measuring tools and other fields.
To sum up, it is mainly used in the following aspects:
1 Turning in continuous cutting.
2 Profiling turning with little change in knife depth.
3 require intermittent vehicles with low intensity.

4 High-speed face milling of steel or gray cast iron.

The advantages of coated cemented carbide are many and summarized as follows:
1 Good versatility.
2 can improve the accuracy of the workpiece cutting surface.
3 The cutting speed is greatly increased at the same tool life.
4 At the same cutting speed, tool life can be increased.
(1) Coating material Most foreign manufacturers use TiC coating for coated inserts, followed by TiN coating. TiC-TiN composite coating and Ti (C ? N) solid solution coating gradually increased. In recent years, many new composite coatings have also been developed.
TiC is currently an ideal coating material, its advantages are high temperature hardness, high strength, good oxidation resistance and crater wear resistance; its disadvantage is that the coefficient of thermal expansion and the body is larger, and the side wear resistance is poor. Compared with the TiC coating, the TiN coating has the following advantages: the coated blade has a low tendency to form a crater when cutting, and its coefficient of thermal expansion is close to that of the substrate, and has a low sensitivity to thermal shock and is not likely to form a tumor. Anti-side wear is good, and it is easy to deposit and control. The disadvantage is that the adhesion to the substrate is less solid. TiC-TiN composite coating and Ti(C?N) solid solution coating are new coatings developed in the 1970s and have been successfully applied in production.
The composite coating hard coating has a promising future.
(2) Coating process The process and equipment for producing TiC coating inserts at home and abroad are similar. The common feature is that the treated cemented carbide inserts are placed in a deposition reaction chamber, and then H2 is used as a carrier to introduce TiCl4 and methane into the reaction chamber. Deposition reaction. The reaction temperature is roughly controlled at about 1000°C. The heating method is almost always the same high-frequency induction heating, and the deposition pressure is mostly negative pressure. Although a good quality coating can be deposited under normal pressure, the use of negative pressure deposition is more efficient and the coating is more uniform and dense. Especially when the number of deposition blades is large, the advantages of using negative pressure deposition are particularly significant.
(3) Coating thickness The thickness of the TiC coating is usually 5~8μm for coating inserts produced at home and abroad. The thickness of TiN coating is in the range of 8~12μm. (4) The coating matrix coating performance is greatly affected by the matrix composition, the coated blade matrix should meet the following requirements: 1 has good toughness and resistance to plastic deformation. 2 has a high hardness. 3 Its chemical composition must match the coating material, and the mutual adhesion should be firm. 4 is not damaged at high deposition temperatures. 5 The coefficient of expansion is similar to that of the coating material. 6 has good thermal conductivity. When machining steel materials, WiC-TC-Co or WC-TiC-TaC-Co alloys should be selected; when machining cast iron or non-ferrous metals, WC-Co alloys should be selected. Different processing materials, the requirements of the coating alloy matrix is also different, meaning that the coating should also be personalized, any heat treatment process is not a panacea, as long as under the specific conditions to maximize their effectiveness.

5. Application of Cemented Carbide in Tool and Die Production

(1) In the field of cutting tools, cemented carbide maintains excellent cutting performance even at high temperatures of 800-1000°C. It is suitable for rapid cutting at high temperatures and has practical significance for improving economic efficiency. Therefore, it is gradually replacing high-speed tool steels. Make tools. In 2017, it has been widely used not only in lathes, planers, boring knives, three-blade cutters, die cutters, and end mills, but also with the continuous promotion of smart manufacturing and industrial 4.0. Broader, looking forward to the future Tool material is undoubtedly the world of hard alloys.
(2) In the field of molds, various types of wire drawing die and wire drawing die are basically made of cemented carbide. The progressive die for making zipper teeth uses YG8 and YG15 hard alloys to make large-diameter drawing dies and YG20C hard dies. Alloys for multi-position progressive die. Non-magnetic mode is generally made of YG15 and YG20 cemented carbide. The service life of YG8 nitrogen ion implanted wire drawing die is more than doubled. In short, the application of cemented carbide in molds is becoming more and more common. It is also used in the gage and other tool industries and will not be described in detail.

6. Conclusion

After the appropriate heat treatment of the hard alloy, although it can improve a little hardness, but taking into account the longer heat treatment time and detrimental to the bending strength, so heat treatment should have a certain degree of specificity. The surface coating strengthens the new path for the use of cemented carbide, and the coating substrate, material, process, and thickness should also be individualized.

28 October, 2020

Hello All,

I have a TCC coating applied to carbon steel inside a vessel. The vessel has the heads welded on and has been PWHT at a hold temp. of 600 DegC. The TCC coating has powdered and started delaminating. Particularly in the nozzle transition areas.
Does anyone have feedback for this failure please?

Leave a Reply

Your email address will not be published. Required fields are marked *

亚洲乱码中文字幕综合-欧美日韩亚洲综合久久精品-美女隐私无遮挡免费网站-国产精品激情av在线播放| 国产精品一区二区小视频-欧美亚洲国产精品激情在线-日韩免费视频一区二区三区视频-精品亚洲国产成av人片传媒| 亚洲一区二区三区四区中文字幕-精品久久久久久蜜臀-国产传媒视频免费观看网站-国产三级在线观看一区二区| 18禁成人一区二区三区av-亚洲热热日韩精品中文字幕-亚洲中文字幕视频第一二区-亚洲国产日韩精品在线| 激情综合亚洲欧美调教-亚洲综合日韩精品国产-国产成人亚洲精品av大片-久草青青亚洲毛片在线视频| 禁播的黄色片精品久久-人妻少妇精品视频久久-巨乳人妻的诱惑在线看-亚洲欧美日韩中文久久| 国内一级一片内射免费视频观-最新国产在线视频在线-免费在线观看国产特级片-国产午夜免费观看在线视频| 亚洲av一区二区三区av-国产av一区二区三区香蕉-久久超碰免费欧美人妻-九一精品人妻一区二区三区| 亚洲天堂成人av影院-日韩精品国产一区在线久草-欧美国产另类久久久精品-91午夜精品久久香蕉| 国产精品中文字幕久久-国产精品一区二区在线免费-韩国午夜三级一区二区-亚洲国产成人精品一区刚刚| 超碰成人av免费观看-伊人色综合久久天天伊人婷-av天堂激情在线观看-国产精品自拍国产精品| 狠狠操夜夜操天天干天天-午夜一级视频在线免费观看-我要看欧美一级黄色录像-91嫩草国产亚洲精品| 欧美日本高清乱码一区二区-国产亚洲精品成人看片-性生交大片免费看淑女出一招-亚洲综合中文字幕综合| 成人av亚洲男人色丁香-色丁香婷婷综合缴情综-国产男女视频免费观看-日韩有码中文字幕一区八戒| 亚洲少妇视频免费观看高清-亚洲午夜福利在线播放-偷拍偷窥精品视频在线-黄色大片国产免费永久网站| 蜜臀av午夜精品福利-日韩精品av在线一区二区-丰满熟女人妻一区二区三区-懂色日韩欧美国产亚洲| 91九色精品人成在线观看-国产成人免费综合激情-新久久国产色av免费看-av网站国产主播在线| 久色视频精品在线观看-在线看片免费人成视久网国产-亚洲精品人妻中文字幕-国产一区二区午夜福利在线观看| 人妻av久久人妻水蜜桃-国产一区视频在线二区-五月婷六月丁香久久综合-国产精品中文字幕有码| 国产精品一区二区蜜桃视频-四十路五十路熟女丰满av-成人av天堂中文在线-亚洲精品成人国产在线| 国产特级黄色录像视频-成人亚洲精品专区高清-国产97在线免费观看-91精品青草福利久久午夜| 中美高清在线观看av-精品视频中文字幕天码-日韩高清一二三区在线观看-精品人妻91一区二区三区| 日本在线无乱码中文字幕-国产美女自拍视频精品一区-精品人妻中文字幕一区二区三区-精品国产一级二级三级| 婷婷激情五月天第四色-岛国片av在线免费观看-久久综合久久一区二区-91青青草原免费观看| 一区二区在线观看黑人-久久久精品人妻一区二区三区综合-成人内射国产免费观看-四虎在线免费视频观看| 亚洲少妇插进去综合网-久草免费在线人妻视频-丰满人妻熟妇乱精品视频-日韩极品精品视频免费在线观看| 一本大道加勒比东京热-国产一二三区亚洲精品美女-国产在线麻豆在拍91精品-久久久久成人亚洲国产| 免费人成视频在线观看播放网站-日韩精品久久精品三级-91精品一区二区三区久久蜜桃-中文字幕av久久激情亚洲精品| 加勒比日本东京热风间由美-少妇高潮喷水高清av-国产免费观看久久黄av-永久成人免费在线视频| av福利在线播放网站-午夜福利在线观看精品-久久精品女人av天堂-日本中文字幕在线乱码| 日韩精品人妻久久久一二三-亚洲精品呻吟久久粉嫩av-女同按摩高潮中出亚洲-亚洲成人精品福利在线| 国产精品综合亚洲综合-精品人妻码一区二区三区红楼视频-亚洲精品一品区二品区三区-日韩欧美色精品噜噜噜| 日本在线观看一区二区免费-日本一区二区精品在线观看-老湿机午夜免费在线观看-成人在线永久免费观看| 国产好大好硬好爽好湿免费视频-国产精品一区二区精品一区二区-白白色发布在线播放国产-99久久国产精品成人观看| 亚洲一级特黄大片做受-国产91喷潮在线观看-日本不卡一区二区三区四区-在线观看高清视频一区二区三区| 麻豆视频传媒在线免费看-亚洲性码不卡视频在线-岛国av色片免费在线观看-久久久国产精品视频大全| 成人av亚洲男人色丁香-色丁香婷婷综合缴情综-国产男女视频免费观看-日韩有码中文字幕一区八戒| 女人毛茸茸的外阴视频-成人激情午夜福利视频-国产精品性色一区二区三区-国产中文字幕欧美激情| 亚洲91精品麻豆国产系列在线-丝袜美腿诱惑一区二区视频-日本人妻中文一区二区-男女无遮挡啪啪啪国产| 欧美日韩你懂的在线观看-国产欧美日韩亚洲一区二区-国产无遮挡裸体免费久久-亚洲国内精品久久久久久| 蜜桃在线观看免费网站-亚洲成熟女性一级黄色蝶片-日韩一级黄色片天天看-一区二区三区在线视频观看美女|