Development of the hottest powder metallurgy tool

2022-08-08
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Development of powder metallurgy tool steel production

preface

powder metallurgy high speed steel (PM HSS) has made great progress in steel variety, quality and output since it was industrialized in the early 1970s. Following the United States' Crucible Company and Sweden's stora company, the bole udelholm group (hereinafter referred to as B-U group), which was formed by the merger of Austria's B hler steel plant and Sweden's uddelholm steel plant in 1992, has emerged as a new force and now plays a decisive role in the production of powder metallurgy tool steel (PM TS) in the world. Now the group is spending a lot of money to establish a new PM TS production line. It is expected that after the production line is completed and put into operation in the fourth quarter of 1999, it will occupy a more important position in the PM TS market. The current consumption of PM ts in the world and the latest development of B-U Group production are summarized below

1 global consumption of P/M tool steel and production of B-U group

global consumption of PM TS

P/M tool steel includes three categories: P/m high speed steel, P/m cold working tool steel and P/M plastic mold steel. In the total consumption of PM ts, PM HSS accounts for about 75%, and the remaining 25% are powder metallurgy cold working tool steel and powder metallurgy plastic mold steel. PM HSS is not only used as cutting tool but also as cold working tool. According to the information from B-U group, the global consumption of PM ts in 1998 (excluding China and CIS countries) was about 9000t per year. Among them, the consumption of PM HSS is about 67px - the comprehensive ring crush strength of corrugated paper base (n/cm); 50t, the consumption of powder metallurgy cold working tool steel and plastic mold steel is about 2250t. This is a relatively accurate figure

b-u group's production and status of PM TS

in 1998, the sales volume of PM ts of B-U group accounted for 19% of the total global consumption, and it was the second supplier of PM ts in the world. In 1998, the group sold about 1710t PM ts, of which 1280t were PM HSS and 430t were powder metallurgy cold working tool steel and plastic mold steel. Previously, B-U group did not produce atomized PM TS powder by itself, but purchased it from companies in Sweden and Ukraine. Then we carry out hot isostatic pressing (hip), forging, hot rolling and other hot processing, as well as finishing and quality inspection of materials. The Group believes that PM TS will have great development in the future. Therefore, strategically, the group should have a complete modern PM TS production line in its own factory, in order to occupy a more important position in the global competition in the future PM TS market. Therefore, the Group invested a huge sum of 300 million Austrian shillings (equivalent to 190million yuan) in the bole steel plant in Kapfenberg, Austria, and laid the foundation in June, 1998 to establish a new modern PM TS production line. The factory covers an area of 2500m2, the office covers an area of 430m2, and 24 operators work in two shifts. It is planned to be completed in the fourth quarter of 1999. After the installation and commissioning of two major new equipment (pulverizing equipment and new hip equipment) are completed and put into operation, the PM TS output of B-U group will account for 27% of the total market in the future, and the quality of steel will reach a new level

2 characteristics of the new PM TS production line of B-U group

the world's first metallurgical plants producing PM HSS are stora steel plant in Sweden (now belonging to Erasteel steel plant in France) and crucible steel plant in the United States, which were established in the early 1970s. Later, according to the design of stora plant, Sweden anval plant and the former Soviet Union Ukraine DSS plant were built to enhance the ability to deal with trade protectionism. So far, the production of PM TS has gradually accumulated a lot of experience, and its production technology is also constantly improving

the PM TS production line established by B-U group is not a copy of the previous PM TS plant, and its main production process will be carried out on the newly designed advanced equipment. Production is roughly divided into the following five processes

1) smelting

smelting scrap steel and alloy is carried out on an 8t induction furnace, as shown in Figure 1

1. Induction furnace 2 Tundish 3 Atomizing device 4 Powder canning 5 Hot isostatic pressing

figure 1b-u group PM TS production process

2) molten steel purification

molten steel purification is carried out in the tundish. The tundish is specially designed to ensure ultra-high purity of molten steel. This is extremely important, because improving the purification degree of steel can reduce the content of non-metallic inclusions in steel, so PM ts can obtain higher strength and toughness, as well as good polishability

it can be seen from Figure 1 that the method adopted by B-U group is basically the same as the new purification process adopted by stora plant since 1994. Graphite electrode is installed on the middle ladle for heating to keep the temperature of molten steel stable during atomization. There is a layer of electroslag liquid with strong metallurgical activity on the liquid steel. The bottom of the intermediate ladle is filled with high-purity nitrogen to help the non-metallic inclusions in the steel float up and be absorbed by the electroslag liquid on the steel surface. It is said that this can reduce about 90% of non-metallic inclusions in steel

pm after the reduction of non-metallic inclusions in HSS, the strength and toughness of HSS can be effectively improved, and the tool breakage can be reduced. In addition, the polishability of steel can be effectively improved after the inclusion reduction (which can be improved from grade 2.5 to grade 0.2). See Table 1 for the specific data of various steel types. This data is also applicable to powder metallurgy die steel. Table 1 polishability of different steel grades

polishing level reached by steel grades asp2000 series purified PM HSS 0.2 traditional PM and electroslag remelting tool steel 1.5 general plastic mold steel 2.5 general cold working tool steel 3.5 data are quoted from the seminar materials of Erasteel factory. PM HSS asp2000

series are steel grades produced by using purified molten steel process

3) preparation of atomized ultra-fine steel powder

high purity nitrogen is used to atomize the purified molten steel into steel powder. The weight of steel powder particles is about 0.2mg. The atomization device of B-U group is self-designed, and its advantage is that it can produce finer ultra-fine steel powder. Using this ultra-fine steel powder can produce high-strength PM HSS in hip state that can be directly used by users without forging or hot rolling after hot isostatic pressing (hip), which can shorten the production cycle and reduce the production cost

4) powder canning

the atomized fine steel powder is put into the low carbon steel tank after screening, and then welded and sealed after vacuum pumping

5) hot isostatic pressing

b-u group ordered the latest modern hip equipment. It has a high-power heater. The canned steel powder can be heated (1150 ~ 1180 ℃) and pressurized (> 100MPa) in the high-pressure container of the hot isostatic press at the same time without preheating, and then it can be forged and hot rolled into PM steel; Or directly made into steel in hip state. This kind of steel can contain high sulfur content (0.2%), so it has good machinability, especially shovel machinability (see table 2s039, s059, S069, s079isomatrix and other steel grades). Table 2 P-U group's P/M tool steel grade

serial number steel chemical composition/% note major steel grade C W Mo cr v co s 1 high speed steel S390

s039 1.6 10.8 2 4.75 5.0 8.0 ≤ 0.03

0.2 forged or rolled products

hip direct production 2 S590

s592

1.31

6.3

5.1

4.2

3.0

8.4 ≤ 0.03

0.2 forged or rolled 3 s059 0.2 hip direct forming 4 s690

s069 1.44 5.6 5.0 4.1 3.7 - <0.03

0.2 forged or rolled products

hip direct forming 5 s790

s079 1.3 6.3 5.1 4.2 3.0 - ≤ 0.03

0.2 forged or rolled products

hip direct forming 10 cold working die steel K190 2.3-1.1 12.5 4.0 - Forged or rolled products 11 plastic die steel m390 1.9 0 0.6 1 20.0 4.0 - Forged or rolled products material 12 high speed steel s392 1.6 10.8 2.0 4.75 5.0 8.0 0 0.2 forged or rolled 13 s692 1.44 5.6 5.0 4.1 3.7-0.2 Steel grade marking method of Bole group: take S390 as an example, it is actually B hler S390 isomatrix, which is abbreviated as S390 in the text and table

3 brand and composition of PM TS produced by B-U group

b-u group currently produces 11 kinds of PM ts, as shown in Table 2. It includes powder metallurgy plastic mold steel B hler m390 isomatrix, powder metallurgy cold working tool steel B hler K190 isomatrix and 9 kinds of PM HSS. Nine pm HSS are four basic components, namely S390, S590, s690 and s790. The first two contain 8% cobalt, and the last two contain no cobalt but high vanadium. In terms of composition, s790 is the M3 Ⅱ type of American AISI, and s690 is the M4 type of American AISI. S590 is the asp30 of stora plant in Sweden, which is the brand of PM steel mills in the world, and the market competition is the fiercest. Only S390 high vanadium and high cobalt grade is the highest performance steel developed by B-U group. The main alloy elements of PM HSS in these components remain unchanged, but 2 ~ 3 modified steel grades are derived according to different sulfur content and whether forged and rolled after hip. Take S590 as an example, there are three varieties of S590, s592 and s059. S590 is low sulfur (s ≤ 0.03%), and s592 is high sulfur (about 0.2%). These two kinds of PM HSS are hip and then forged and hot rolled. S059 is a high sulfur (0.2%) variety, but after 13. It has the function of returning to the initial position after the experiment, hip will not be forged or hot rolled, that is, hip directly reaches the required size. These three different PM HSS can be selected by users with different needs

b-u group will produce traditional powder metallurgy products on this new PM TS production line, and will also develop several new products of great significance for its future development. These new products have been successfully developed, such as No.11, 12, 13 and other steel grades in Table 2, especially No.11, whose chromium content is as high as 20%, excellent wear resistance and good corrosion resistance. (end)

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