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34CrNiMo6 Intorcution –classification and chemical analysis

34CrNiMo6 Introduction –classification and chemical analysis

classification:

① quenched and tempered structural steel

②Surface hardened structural steel

① The carbon content of quenched and tempered steels is generally about 0.25% to 0.55%. For structural parts of a given cross-sectional size, when quenching and tempering along the cross-section during quenching and tempering (quenching and tempering), the mechanical properties are good. If it is not quenched and free ferrite appears in the microstructure, the toughness decreases. For steels with a tendency to temper brittleness, such as manganese steel, chromium steel, nickel-chromium steel, etc., they should be cooled quickly after tempering. The critical quenching diameter of this type of steel increases with the increase in grain size and alloying element content. For example, 40cr and 35simn steel is about 30-40mm, and 40crnimo and 30crni2mov steel is about 60-100mm, which is commonly used in manufacturing Structural parts such as shafts and connecting rods with large loads.

②Surface hardened structural steel is used to manufacture hard and wear-resistant surface parts and flexible parts, such as gears and shafts. In order to increase the toughness of the core of the part, the carbon content in the steel should be low, generally 0.12 to 0.25%, and there is also an appropriate amount of alloying elements to ensure proper hardenability. Nitrided steel also needs to add alloy elements (such as al, cr, mo, etc.) that are easy to form nitrides. Carburized or carbonitrided steel, after carburizing or carbonitriding at 850 ～ 950 ℃, quenched and used under low-temperature tempering (about 200 ℃). The nitrided steel is directly treated by nitriding (480 ～ 580 ℃), and it is no longer quenched and tempered.

34CrNiMo6 (1.6582) belongs to European standard high-strength alloy structural steel.

According to the carbon equivalent calculation formula recommended by the International Welding Society (IIW) Ceq = C + 1 / 6Mn + 1/5 (Cr + Mo + V) +1/15 (Ni + Cu) (%)

(1) When Ceq <0.40%;

(2) When Ceq = 0.40 ～ 0.60%, the hardening tendency of the steel gradually becomes obvious, and the weldability is acceptable. When welding, appropriate preheating before welding and slow cooling after welding should be adopted to control its welding line energy;

(3) When Ceq> 0.60%, the steel has a strong hard tendency and poor weldability. It is a steel type that is more difficult to weld, and a higher preheating temperature and strict process measures must be taken to select suitable welding. material. It is calculated that the carbon equivalent value of 35CrMo steel Ceq = 0.72%.

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Our OTAI stocks 1.7225 42CrMo4 steel plates and keeps daily inventory of 1000tons. We are the biggest stockiest in south of China.

As this item is our hot selling items, we exports this 1.7225 42CrMo4 to more than 35 countries from EU, Middle East and Asia. The steel materials meet DIN, ASTM, EN, JIS and so on in different international standards.

Now as the virus affect, the material for this 1.7225 42CrMo4 and the DC53 steel material became the internet hot selling material now. Because the 1.7225 42CrMo4 is for the mask mold tool apply on the normal mask manufacturing.And the DC53 is for the mold tool using on the N95 mask manufacturing.

What we learn from this virus? 

And recently, I saw some report and news about the blame games for this virus. Sometimes, as the human being, we should learn something from this virus lessons. Sometimes, we underreact and in other situations we overreact, and for a reason. Facing the coronavirus, China, Japan, EU and USA all struggles, although for different reasons. China worried about sounding a false alarm and causing panic in January. When they knew little at the very beginning, by the time of the Wuhan lockdown, there were only 570 documented cases and 17deaths. These numbers were alarming but not very illuminating. The Chinese chose to overreact, they closed off an entire province, the size of Portugal and Hungary put together. But a month of data should have made a huge difference.

In late Feb many countries chose to underreact, they had other things to worry about. The Japanese did not want to delay the Olympics. The Europeans doubted the necessity to change their way of life. And the Americans hated to shut down what is the biggest world economy. Should we blame them? Maybe. But is is always easy to judge with the benefit of hindsight. Foresight is totally another thing. You could be right and you could be wrong.

Donald Trump said : I am instructing my administration to halt funding of the World Health Organization . While a review is conducted to assess the World Health Organization’s role in severely mismanaging and covering up the spread of the coronavirus.Today, America blamed the WHO for doing too little too late. In 2009, the WHO was also blamed but for a different reason. It was criticized for overreacting. The swine flu that originated from a Mexico farm was declared as a pandemic. Because it looked like and acted like one. It turned out to kill only 0.01 percent of the infected, lower than a seasonal flu. And the world paid a huge sum of money and human resources to contain it. People blamed the WHO for overshooting. To be continued…

Ms Phoenix Li

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As recently, the 4140 flat bar and other bars orders are increasing heavily. And for increasing the speed and capacity on the cutting flat bars, our company added a new big Vertical Sawing machine. The speed and efficiency is double more than the before normal cutting machine.

And usually, our company will make the stock for our running item 4140 steel plates. When we received the official order , we will arrange to cut it into 4140 flat bar as request. So normally, customers are very happy to have the one stop solution service from us. As we have our own cutting machine, milling, grinding equipments or even the testing. It really makes them without any worry. Our OTAI not only could supply the 4140 flat bar, but also other different steel material like tool steel, high speed steel in flat bars, round bars.

In last chapter, we talked about what we learned from the virus, now let’s continue to the next.We are all humans and we are susceptible to making wrong calls, especially with limited data and unlimited stress. The fact of the matter is our science is only as good as the data we have. In the early hours, we simply don’t have good data. Scientists know it, but the public don’t. We expect clarity and simplicity. But it unfortunately is a bridge too far in the land of a new virus. To make matters worse, the impulse to think of the world as a place with simple answers,may get us into rounds of blame games.

People say things like the virus exists because the Chinese eat bats. The spread is because somebody hid the information. That sound right and make you feel vindicated, but they are not real reasons. But there is a peril in buying into these simplistic messages. It stops us finding our own blind spots.If the Chinese are not humble, they would fail to upgrade the early warning system. If the Europeans are too proud, they would not appreciate the merits of a strong union. If the Americans are obsessed with being first, they would be the last to fix the broken public health system.

The blame game does not help at all. It blows things out of proportion.And it skews our understanding without our knowledge. It denies us the chance to be better and wiser. A pandemic like this has happened before, it is happening now and will happen again. And our human response may not be perfect. But we are better every time because we learn.Humans have beaten the small pox and SARS. We have a good chance to beat this one. But it takes time and most importantly it takes all of us to be honest and humble.

And there is only one thing that can make us honest and humble. That is truth backed by data and science. Data says what medicine works, not politicians. Data says where the virus came from, not senators. And scientists say don’t have enough data yet. The real truth has no regard for what you think and who you are. That may make us uncomfortable. But if you are brave enough, you will accept the world as it is, not as you want it to be.

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Otai company provides the DC53 die steel for the mask factory. We will provide a premium mask mold to meet the demand for mask manufacturing.

Today is Monday, the first day of a new week, I am wondering what to share with customers. Our company locates in Dongguang city, Guangdong province. The weather turns to be hot. Because of the pandemic, we also have to wear the mask every day to control the spreading of the virus. However, I read a news that many people gathering beside the beach without wearing a mask. It is very dangerous, I hope the days without wearing a mask will come soon. Otai company provides the DC53 die steel for the mask factory. We will provide a premium mask mold to meet the demand for mask manufacturing.

Although almost five-month past, the virus doesn’t disappear. The hottest days are around the corner. Although it is un-convenient for us to keep social distance, wearing a mask. However, we have to keep doing this to shorten the hard times. Even though the virus is under control in China, most of the people still keep the masks. The new arrival of DC53 die steel is still popular at our company. We are busy producing the mask mold every day. We not only provide the N95 mask mold but also provides the Ultrasound parts for mask mold. As we have talked before, DC53 steel is a good choice for mask mold manufacture. The quality is better than other materials.

Properties of DC53 die steel

Cold work DC53 die steel overcomes the insufficient of SKD11 high-temperature tempering hardness and toughness of weakness, DC53 tool steel will fully replace SKD11 tool steel in the field of general and precision mold. Its toughness is 2 times of SKD11, DC53 toughness is more prominent in the cold work die. Made of DC53 tools steel rarely appears crack and craze, greatly improving the service life.

The DC53 steel has a uniform distribution of fine carbides. It has great galling and wears and fatigue resistance. It has also a High temper resistance to support PVD & nitride surface treatments. And it has Machining and grinding properties are superior to most other tool steels.

Hoping the day we can freely go outside without wearing a mask, if you have demand about the mask mold, please feel free to contact me.

Mr Jack Tan

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how to improve the lifetime of die made of the 1.2344 die steel ? We can talk about it from the improvement of the heat treatment.

2. Heat treatment strengthening of 1.2344 die steel

The main structure of 1.2344 die steel in the annealing state is pearlite. and its performance is not up to the requirements of the mold. so it must be hardened and tempered to improve its overall performance.

In the quenching stage, the steel is heated above the austenitizing temperature. and then the steel is cooled with a greater degree of supercooling to obtain the hardened martensite structure. In the tempering stage, the steel is reheated to the austenitizing temperature. and the hardened martensite structure is transformed into a tempered martensite structure, to improve the comprehensive properties of the steel.

1) the quenching phase of 1.2344 die steel

Through the metallographic analysis of a large number of dies with premature failure, it is found that the coarse austenite grain is one of the important reasons leading to the premature failure of dies. The thickness of austenite grain is directly related to the service life of the die.

The larger the grain size, the greater the tendency of cracking and distortion during quenching. Therefore, the austenite grain size must be controlled effectively.

The original structure and thermal conditions of steel will affect the austenite crystal. Therefore, in the quenching phase, to obtain fine grain austenite, it is necessary to strictly control the heating temperature and holding time.

2) tempering stage of 1.2344 die steel

After the steel is hardened, there will be greater internal stress. The purpose of subsequent tempering is to remove the internal stress and make the metastable structure stable.

Too much residual austenite will reduce quenching hardness and embrittlement will occur during use due to aging deformation (transformation into martensite). General primary tempering can not reduce the residual austenite to a reasonable level. In actual production, secondary tempering is used, the tempering temperature is usually about 590℃, and air cooling.

Since martensite is formed during rapid cooling, air cooling occurs after each tempering to create a temperature gradient that allows the residual austenite to be transformed more thoroughly. After the second tempering, the hardness of the workpiece is maintained at HRC 47-50 to ensure that its performance meets the requirements.

The quality control of die steel is very important, it affects the life of die, product quality, and production efficiency.

Mr Jack Tan

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When 1.2344 die steel is used as hot die steel, how to improve the lifetime of die?

1.2344 die steel is the most widely used hot die steel. However, with the development of the aluminum extrusion industry, high- requirement for the extrusion mold is needed.

Effect of chemical composition on properties of 1.2344 die steel

1, C content is directly proportional to the strength of the steel, the increase of C content in the steel will improve the strength of the steel. for hot die steel, it will make the high-temperature strength, thermal hardness and wear resistance, but will lead to the reduction of its toughness.

2. Cr has a favorable influence on the abrasion resistance, high-temperature strength, thermal hardness, toughness and hardenability of steel. When the content is high, the tempering resistance is also high, and the corrosion resistance of steel will be improved obviously when it melts into the matrix.
3. Ti, V, and Mo elements. In the forging or quenching stage, carbide forming elements such as Ti and v. Mo will form alloy carbides insoluble in austenite, thus impeding austenite grain growth and refining austenite grain.

Also, in the tempering process stage, because 1.2344 die steel contains more carbide forming elements (Ti, V, Mo), when the tempering temperature is higher than 500℃, the cementite dissolves, forming a small, dispersed alloy carbide. The secondary hardening of H13 can be caused by the dispersion of alloy carbide.

Microstructure and properties of 1.2344 die steel

1. Spheroidized annealing structure

When H13 steel is accepted in the annealed state, the main structure of steel in this state is pearlite. The morphology of pearlite is different with the different annealing process. Compared with the flake pearlite with the same chemical composition, granular pearlite has lower strength and hardness, but better plastic toughness.

For H13 steel in the annealed state, the original structure is generally required to be a point or granular pearlite to facilitate subsequent machining and forming, and to obtain austenite with refined grain in the quenching stage.

to be continued

Mr Jack Tan

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1.2311 steel is a German mold steel. The steel is produced through “ultra-purity” process, pre-hardened. It presents a high degree of micro-purity and excellent homogenous structure, excellent polishing and photo-etching floral properties. It is with good processing and polishing performance, more suitable Electric fire processing. Under conventional smelting, the steel has excellent quenching and tempering heat treatment properties.

1.2311 steel delivery condition: Hardened and tempered, the hardness is 28~36HRC.

1.2311 Reference corresponding grade

Chinese GB / YB standard grade is 5CrMnMo. Japanese JIS standard grade is SKT3. German DIN standard material grade is 1.2311. American AISI standard grade 6G, GOST TOCT standard grade 5XTM.

1.2311 steel related applications

1) Used for die casting molds of zinc, aluminum, magnesium and their alloys.

2) Used for hot stamping dies and various hot forging dies.

3) Used for metal extrusion die base.

4) Suitable for the production of large and medium-sized injection molds, as well as plastic molds with polishing requirements.

5) Used for making general plastic molds and mold bases.

6) Used as plastic mold base, mold base, die-cast mold base.

7) It can be used for plastic molds with tensile stress around 1000Mpa.

8) Suitable for small and medium-sized molds with thickness less than 400mm.

Recently, the price for the plastic mold steel is not very stable because of the virus situation. Now in China, the very busy companies are those ones which are producing the facemask and respirators. As the huge need from different countries, the orders are much more than the production capacity. Consequently, the mold steel material costs are increasing crazily because of the die and tool needed on these machines. So in few weeks ago, the 1.2311 steel price was up to EXW USD857/Ton. Now for supporting the work, our company make the special offer on this 1.2311 steel. The FOB price starts USD770/Ton for the thickness 20-120mm. But the valid time will be until this week 18th-April.

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High-speed steel and alloy steel, which one is suitable for drills ?HSS is used as the drills, Otai provides the M2, M42, M35 steel for our customers.

There are many kinds of drill bits on the market, such as twist drill, inner cold twist drill, step drill, inner cold step drill, and other non-standard drill bits. But the materials used in these drills are generally summed up in two broad categories.

1. High-speed steel

High-speed steel (HSS) is a tool steel with rigid hardness, high wear resistance, and high heat resistance. High-speed steel tool is a tool than ordinary tools to be tough, easier to cut, high-speed steel than carbon tool steel has better toughness, strength, heat resistance, cutting speed than carbon tool steel (iron-carbon alloy) is much higher, so it is called high-speed steel; And hard alloy is better than high – speed steel, cutting speed can be increased 2-3 times.

Features:

High-speed steel red hardness up to 650 degrees.

HSS has good strength and toughness, sharp cutting after sharpening, stable quality, and is generally used to make small and complicated cutting tools.

2. Cemented carbide(alloy steel)

The carbide bit is mainly made of tungsten carbide and cobalt carbide, which account for 99% of all the components and 1% of other metals, so it is called tungsten steel (cemented carbide). Tungsten steel is a sintered composite material consisting of at least one metal carbide. Tungsten carbide, cobalt carbide, niobium carbide, titanium carbide, tantalum carbide are common components of tungsten steel.

features:

The red hardness of cemented carbide can reach 800-1000 degrees.

The cutting speed of cemented carbide is 4-7 times higher than that of HSS, and the cutting efficiency is high.

The disadvantages are low flexural strength, poor impact toughness, high brittleness, and low shock resistance.

Commonly speaking, HSS is used as the drills, Otai provides the M2, M42, M35 steel for our customers. Welcome to send me an inquiry.

Mr Jack Tan

Tel: 0086-769-23190193

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42crmo4 steel is the key product of Otai company, it is popular among our customer. I wound like to talk about 42crmo4 steel applies in the Gear making.

42crmo4 steel is the key product of Otai company, it is popular among our customer. It can be used in different industry. I wound like to talk about 42crmo4 steel applies in the Gear making.

Key performance requirements for high quality gear

High quality gear steel is mainly shown in three aspects: narrow end quenching zone, high purity and fine and uniform grain.

(1) end quench band

The stability of the hardenability of the end has a great influence on the quantity of heat treatment deformation of gear steel.

(2) purity

Purity mainly refers to the decrease of oxygen content and other harmful elements. The influence of oxygen content on the fatigue life of gears has been paid more and more attention. In order to improve the purity and reduce harmful inclusions, the content of Ti in gear steel should be limited, It is the source of fatigue crack.

(3) grain size

Grain size is another important index of gear steel, because coarse grain makes the concentration of penetration layer relative increase, resulting in the increase of brittleness, make the product strength decline, the tooth surface easy to peel off. If mixed crystals appear, the heat treatment deformation between the aging teeth may lose its rules and cannot be matched. In the aspect of structure control technology of gear steel, fine austenite grain is important to the stability of steel and its products, and is the basic property of high quality steel.

why is the 42crmo4 steel applies in the Gear making.

42CrMo4 steel material is a high quality Quenched and Tempered Alloy Structural steel . It belongs to the high quality medium carbon alloy steel, Oil Quenched & Tempered Hardenss is 28-34 HRC .  Annealing delivery hardenss less than 250HB . This materials was the best choose for produce gears .It has high creep strength and durable strength at high temperature. Its hardenability is high, it has good toughness, the possibility of  quenching deformation is  small.

Mr Jack Tan

Tel: 0086-769-23190193

Fax: 0086-769-88705839

Email: jack@otaisteel.com