Analysis of the most popular materials used in Ame

2022-08-25
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"The application of high speed steel and ultra high speed steel in cold working dies is growing rapidly. It is mainly due to the high 'compressive strength/Hardness' ratio. And the hardness can be selected between HRC."

American die steel series and selection scheme were initially formed in the 1940s

analysis of materials used in American mold industry

according to the service conditions of molds, mold steels are divided into three categories in the United States. The tool steel Committee of the American metal society lists three categories: cold work mold steels, hot work mold steels and plastic mold steels. Among them, cold working die steel is divided into 12 sub categories, hot working die steel 9 sub categories and plastic die steel 2 sub categories. The material selection of each sub category depends on three main factors:

· complexity of size and shape

· processed materials

· durability requirements or design life

classification of cold working die steel

cold working die steel is divided into five groups: w group, O group, a group, D group and s group

the utilization of plastic technology in the oil pan has become a trend of future development. Group W, namely, water quenched tool steel, has 11 steel grades and 7 carbon tool steels, with carbon content ranging from 0.7% to 1.3%

o group, i.e. oil quenched die steel (commonly known as oil steel), has four steel grades with a carbon content of 0 55%。

a group is air quenched medium alloy cold working die steel, with 9 steel grades and carbon content ranging from 0 25%。

d group is high carbon and high chromium cold working die steel, with 7 steel grades and carbon content of 0.9% - 2.5%

s group is impact resistant tool steel, with 7 steel grades and carbon content of 0 6%。

there are also high speed steel (HSS group) and ultra high speed steel (SHSS group), cobalt based cemented carbide and steel bonded cemented carbide (HA group), powder steel and engineering ceramics (PIM group), carbon tungsten tool steel (F Group), and special purpose tool steel (L Group)

selection of cold working die steel

the main series of cold working die steel is high hard cold working, which is mainly used for dies requiring high compression and wear resistance, and its hardness is higher than HRC. For molds that require impact resistance and high toughness, the hardness is lower than HRC, mainly S-class and some A-class and the most common quenched and tempered steel, spring steel, hot work mold or matrix steel. For large stamping dies, such as automotive appearance stamping parts, cast iron is mainly used. Simple or life-span with a small number of zinc based alloy or polymer after 1 will loosen the composite material

the application of operating procedures of high speed steel and ultra high speed steel mortar tensile testing machines in cold working molds is growing rapidly. It mainly has a high "compressive strength/hardness" ratio. And the hardness can be selected between HRC

powder die steel has excellent wear-resistant life, and its hardness is not greater than HRC, so it is widely used

carbon tool steel still has a certain range of applications in punches or soft material stamping dies with a service life of 100000 pieces

classification of hot work die steels

Hot Work Die Steels in the United States are divided into two categories: Hot Work Die Steels and super hot strength alloys

selection of hot work die steel

because the hot work die works under the condition of temperature, the material is required to have thermal strength and thermal wear resistance. In order to ensure the service life of the die, the die should be cooled, and the hot and cold alternate die will crack, that is, thermal fatigue crack, so the material also requires crack resistance and thermal fatigue resistance

select materials according to the main series of thermal strength:

low alloy quenched and tempered die steel (6G, 6F2, 6F3) - Medium Chromium hot work die steel (H11, H12, H13) - tungsten hot work die steel (H21, H22)

non standard hot work die steel: such as 6H4 of age hardening type for hot upsetting dies. When H11, H12 and H13 cannot meet the thermal wear resistance, 6h1 and 6H2 can be selected

when hot work wear resistance is required for the mold, D2, D4 - m2, M4 - powder steel can be selected. Steel bonded cemented carbides and cobalt based cemented carbides have high high-temperature wear resistance, but their thermal fatigue (i.e. cold and hot fatigue crack resistance) is very poor, so they cannot be used in the state of rapid cooling and heating

plastic mold steel is divided into five categories according to the overall deployment of the State Council on accelerating the cultivation and development of strategic emerging industries

the United States is the first country to list special steel for plastic mold in tool steel, mainly represented by P

carburized plastic mold steel: P1, P2, P3, P4, P5, p6. The carbon content of this kind of steel is very low, mainly in the early United States and the extrusion molding method, which requires good cold plasticity, high extrusion performance, surface carburization and quenching after forming to improve surface hardness and long service life. Ultra low carbon in the core can minimize the deformation during quenching

tempered plastic mold: P20, p21. At present, there is a large amount of P20 in plastic molds, which has become the main body, and most of them are used in the pre hardening state

medium carbon alloy tool steel is used for thermosetting plastic mold. Steel grades are H13, while L12 and S7, O1 and A2 are also used. The characteristics of this kind are:

1. It is basically a secondary hardening steel with good thermal strength at ℃

2. High chromium content and good atmospheric corrosion

3. Excellent hardenability, suitable for large modules

stainless steel is used for plastic molds with high corrosion resistance requirements. The main steel grades are 420414l and 440416

aging steel has high service performance after aging treatment. There are two kinds, one is p21 low carbon Ni-A1 aging steel; The other is 18Ni Maraging steel. The latter is a carbon free, high purity, high strength and high toughness material used in the aerospace industry. It is used in plastic molds that require high mechanical properties, dimensional accuracy, finish and corrosion resistance

selection of plastic mold steel

thin-walled plastic box. When the production batch is less than 100000 pieces, P20 and p21 are used for pre hardening (HB), and 414l is used when the corrosion is strong

common plastic mold with high service life, P6 or P20, carburized and quenched, and its hardness is HRC; When plastic parts are not too large, O1 and S7 can be used. Use 420 when corrosive

non high temperature thermosetting moulds P6 and P20 are used after carburizing and quenching. Highly corrosive 420

H13 and S7 or carburized steel P4 for high temperature thermosetting plastic molding. These high chromium have good tempering resistance and high temperature oxidation resistance. (end)

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