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4340 steel vs 8620 steel: For the different material comparisons, which one we should choose to use?

4340 steel China suppliers, wholesale, distributors, and stockholder–Dongguan Otai Special Steel Co Ltd. We Otai is a manufacturer and has a large quantity of stock in our warehouse. We supply in Round bar, gauge plate steel, pipe, tube, rod, square, hexagonal, blanks, plate, sheet, precision ground flat bar. Including precision ground bar stock, hollow bar, we provide black surface and black surface alloy steel material.

4340 alloy structural steel belongs to gear steel.

It is used for important tempering parts that require good toughness, high strength, and large size. Such as heavy machinery high-load shaft, turbine shaft with a diameter greater than 250mm. Also, it can be used for helicopter rotor shaft, turbojet engine turboshaft, blade, high-load transmission parts, crankshaft fasteners and etc. Besides, it can also be used for rotor shaft and blade with an operating temperature of over 400℃. It can also be used to make important parts with special performance requirements after nitriding treatment, which can be used for ultra-high-strength steel after low-temperature tempering or isothermal quenching.

8620 is the structural steel with the hardenability guaranteed by American standards, and the standard is as follows: ASTM A29/ A29m-2015 (hot forged and cold processed carbon steel and alloy steel bar).

It has high hardenability, no tempering brittleness, good weldability, little tendency to form a cold crack, good machinability, and cold strain plasticity. Generally used in quenching and tempering or carburizing state, used for manufacturing small and medium-sized automobile, tractor engine and gear in the transmission system, oil drilling and metallurgy open mine cone bit teeth and teeth body, manufacturing steam turbine gear whole rotor internal combustion engine connecting rod valve section forgings. At the same time, the surface of 8620 steel after carburizing heat treatment has relatively high hardness, wear-resistance, and contact fatigue strength, while the core retains good toughness and can withstand high impact load. It can be used as automobile bearing, spindle, gear, mechanical parts, and other impact-resistant, wear-resistant workpieces.

Otai provides the grinding, milling, polishing, turning, drilling, and other machining services as your required tolerances and size.

Otai does not act as a material handler. We possess proprietary technology and continuously iterate. We undertake every order to end and solve customers’ problems without any hesitation on responsibility. We are welcome to your kind inquiry.

A2 Steel vs 4140 steel: Their material comparison

A2 tool steel China suppliers, wholesale, distributors, and stockholder–Dongguan Otai Special Steel Co Ltd. We Otai is a manufacturer and has a large quantity of stock in our warehouse. We supply in Round bar, gauge plate steel, pipe, tube, rod, square, hexagonal, blanks, plate, sheet, precision ground flat bar. Including precision ground bar stock, hollow bar, we provide black surface and black surface alloy steel material.

A2 Tool Steel/1.2363 is a German Cold work tool alloy steel material grade.

A-2 steel is an air hardening alloy chromium-molybdenum-Vanadium die steel. As cold work steel, its grade contains 5% chromium. In applications that require greater size stability, A2 steel is preferable to O1 tool steel.

A typical application such as blanking die, the molding dies, blanking dies, stamping die, stamping die, die, extrusion die, boxing, shear knife blade, instrumentation, knurling tools, volume, head, and machine parts.

4140 steel, the steel has good workability, machining deformation of small, anti-fatigue performance is quite good.

On the hardenability of steel, 4140 heat treatment has good strength and good comprehensive mechanical properties, good manufacturability, high yield. The highest temperature is 427 degrees Celsius. 4140 strength, high hardenability, and good toughness, quenching deformation of small, high temperature creep rupture strength, and high. It is used for manufacturing forgings with higher strength and larger tempering cross-section than 35CrMo steel. Such as big gear for locomotive traction, supercharger drive gear, rear axle, connecting rod, and spring clamp with the great load. Also can be used for drilling pipe joint and fishing tool of oil deep well below 2000m and can be used for bending machine mold, etc.

Otai provides the grinding, milling, polishing, turning, drilling, and other machining services as your required tolerances and size. We are welcome to your kind inquiry. (A2 Steel vs 4140 steel)

4140 hot rolled plate producing

4140 steel plate

4140 plate stocking

4140 hot rolled plate

4140 hot rolled plate stocking

4140  plates loading

5 trucks totally 160 tons 4140 steel plates loading

4140 plates 42CrMo4 plates SCM440 plates 1.7225 plates

Tool steel making 1.2379

1.2379 Tool Steel | D2 | SKD11 | Cr12Mo1V1 Alloy Steel

16MnCr5 Case Hardening Steel

1.16MnCr5 This grade is a low alloy chromium, manganese case hardening steel.

Carburised 16MnCr5 gives a hard case with a strong core whilst retaining a degree of toughness.

It is suited for applications which require a combination of toughness and wear resistance and is commonly supplied in round bar.

2.16MnCr5 Chemical composition

3.16MnCr5 Mechanical Properties

The mechanical properties of annealed DIN 16MnCr5|1.7131 gearing steel (typical for steel) are outlined in the table below:

4.16MnCr5 Applications

DIN 16MnCr5|1.7131 steel is widely used for a variety of applications in the used to the gearings in rotating machinery.

Typical applications such as valve bodies, pumps and fittings, the high load of wheel, bolts, double-headed bolts, gears, internal combustion engine. Electric locomotives, machine tools, tractors, steel rolling equipment, boring machine, railway vehicle, and mining machinery transmission shaft on the steel ball, roller and shaft sleeve, etc.

https://otaialloysteel.com/16mncr5/

16MnCr5 Case Hardening Steel

60Si2MnA Alloy Steel Spring Steel

Otai Specials steel 60Si2MnA Alloy Steel Round Bar 60Si2Mn Spring Steel

Bearing Steel 100Cr6-Through-hardening Bearing Steel

Chemical composition

Through-hardening steel contains typically 1% carbon and alloying elements for hardenability, exhibiting very high strength but low ductility. Used with martensitic or bainitic hardening.

100Cr6 is equivalent to AISI 52100, GB GCr15.

Heat Treatment

In order to harden steel, the iron matrix must contain a certain amount of carbon.

The higher carbon content in the steel the higher achievable hardness. In through-hardening steel, there is a relatively high level of carbon added to the steel. When the component is heat treated, it becomes hard all the way through from the surface to the core, hence the term “through-hardened”. Through-hardened steel components are relatively brittle and can fracture under impact or shock loads.

Applications

for through-hardening bearing steel are typically roller bearing components but also components that require high fatigue strength such as diesel injection components.

The hardness levels these steel reach also makes them excellent in wear applications or cutting/slitting/grinding applications.

When also combined with a stabilizing heat treatment they give a dimensional stability needed in many tool steel applications.

What is Engineering Steel?-30crnimo8-Alloy Steel

30crnimo8 round bar stock

1.Grade 30CrNiMo8 is used for production of heavily loaded parts, shafts and drive axes, steering shafts, crankshafts of engines, screws and elements exposed to temperatures in the power industry.

2. 30CrNiMo8 equal to 1.6580, 30NCD8, 30CND8 alloy steel

3. Alloyed structural steel with medium hardenability designed for heavy duty components, characterized by high elasticity and strength properties reaching over 1560 N/mm2 at small diameters. When softened, the hardness reaches max. 248 HRB.

4 development direction of special steel bearing steel

Bearings are widely used in mining machinery, precision machine tools, metallurgical equipment, heavy equipment and high-end cars and other major equipment fields, as well as wind power generation, high-speed rail motor cars and aerospace and other emerging industries. The bearings produced in China are mainly medium and low-end bearings and small and medium-sized bearings, which are characterized by low-end surplus and high-end lack. Compared with foreign countries, there is a big gap in high-end bearings and large bearings. China’s high-speed railway passenger car special supporting wheelset bearings all need to be imported from abroad. For the key bearings used in aerospace, high-speed railway, high-end cars and other industrial fields, there is a big gap between China’s bearings and the advanced level in service life, reliability, DN value and bearing capacity. For example, the service life of foreign automobile gearbox bearings is the lowest of 500000 km, while the service life of domestic similar bearings is about 100000 km, with poor reliability and stability.
Aviation
As a key basic component of aero-engine, the second generation aero-engine bearing with thrust ratio of 15-20 is being developed abroad, which is ready to be assembled into the fifth generation fighter around 2020. In the past 10 years, the United States has developed the second generation of bearing steel for aero-engine, and the representative steels are css-42l with high strength and corrosion resistance at 500 ℃ and x30 (cronidur30) with high nitrogen and rust resistance at 350 ℃. China is developing the second generation of bearing steel for aero-engine.
Automobile
For automotive hub bearings, the first and second generation of hub bearings (ball bearings) are widely used in China, while the third generation of hub bearings have been widely used in Europe. The main advantages of the third generation hub bearings are reliability, short payload spacing, easy installation, no adjustment, compact structure, etc. At present, most of the imported vehicles in China adopt this kind of lightweight and integrated hub bearing.
Railway vehicles
At present, China’s railway heavy haul train bearings are made of domestic ESR g20crni2moa carburized steel, while foreign countries have applied the vacuum degassing smelting technology, inclusion homogenization technology (IQ steel), ultra long life Steel Technology (TF steel), fine heat treatment technology, high purity bearing steel (EP steel) and other technologies Surface super hardening treatment technology and advanced sealing lubrication technology are applied to the production and manufacturing of bearings, which greatly improves the service life and reliability of bearings. The quality of ESR bearing steel in China is not only low, but also the cost is 2000-3000 yuan / ton higher than that of vacuum degassing steel. In the future, China needs to develop ultra-high purity, fine-grained, homogenized and stable quality vacuum degassing bearing steel to replace the current ESR bearing steel.
Wind power and energy
For wind turbine bearings, at present, China has not been able to produce high-tech spindle bearings and speed increaser bearings, basically relying on imports, and the localization of bearings for wind turbine units above 3MW has not been solved. In order to improve the strength, toughness and service life of wind turbine bearings abroad, a new type of special heat treatment steel SHX (40crsimo) is used. For yaw and variable pitch bearings, the depth of hardened layer, surface hardness, width of soft belt and surface crack are controlled by surface induction hardening heat treatment; Carbonitriding is used for speed increaser bearing and main shaft bearing, so that more stable volume fraction of retained austenite (30% – 35%) and a large number of fine carbides and carbonitrides can be obtained on the surface of parts, and the service life of bearing under pollution lubrication condition is improved.
In order to improve the service life and operation accuracy of rolling mill bearings, it is necessary to research and develop ultra-high purity vacuum degassing smelting of GCr15SiMn and g20cr2ni4 bearing steels for rolling mill and large austenite mass control heat treatment of bearing surface in the future. NSK and NTN have developed the surface austenite strengthening technology respectively, that is, TF bearing and WTF bearing have been developed by increasing the surface austenite content, so that the service life of bearing has been increased by 6-10 times.

The future R & D direction of bearing steel in China is mainly reflected in four aspects:
One is economic cleanliness: on the premise of considering economy, further improve the cleanliness of the steel, reduce the content of oxygen and titanium in the steel, so that the mass fraction of oxygen and titanium in the bearing steel is less than 6 × 10-6 and 15 × The content and size of inclusions in the steel are reduced and the distribution uniformity is improved.
The second is the refinement and homogenization of microstructure: through the application of alloying design and controlled rolling and cooling process, the uniformity of inclusions and carbides can be further improved, the network and band carbides can be reduced and eliminated, the average size and maximum particle size can be reduced, and the average size of carbides can be less than 1 μ The goal of M; The grain size of the matrix is further improved, and the grain size of the bearing steel is further refined.
The third is to reduce macrostructure defects: further reduce the central porosity, central shrinkage and central composition segregation in bearing steel, and improve the uniformity of macrostructure.
Fourth, high toughness of bearing steel: through new alloying, hot rolling process optimization and heat treatment process research, improve the toughness of bearing steel.

heat treatment of H13 die steel

1. Soft spots on the surface of the mold
There are soft spots on the surface of H13 tool/die steel after heat treatment, which will affect the wear resistance of the too/diel and reduce the service life of the die.
(1) Causes
1) There are oxide scale, rust spot and local decarburization on the surface of the mould before heat treatment.
2) After the mold is quenched and heated, the selection of cooling and quenching medium is improper, and the impurities in the quenching medium are too much or aging.
(2) Preventive measures
1) The oxide scale and rust should be removed before the heat treatment of the mould. The surface of the mould should be properly protected during quenching and heating. The mould should be heated in vacuum electric furnace, salt bath furnace and protective atmosphere furnace as far as possible.
2) When the mold is cooled after quenching and heating, the appropriate cooling medium should be selected, and the cooling medium used for a long time should be filtered or replaced regularly.
2. Poor organization of die before heat treatment
The final spheroidizing structure of the die is coarse and uneven, the spheroidizing is not perfect, and there are network, band and chain carbides in the structure, which will make the die easy to produce cracks after quenching and cause the die to be scrapped.
(1) Causes
1) There is serious carbide segregation in the original structure of die steel.
2) Poor forging process, such as too high forging heating temperature, small deformation, high stop forging temperature, slow cooling rate after forging, makes the forging structure coarse and has network, band and chain carbide, which is difficult to eliminate during spheroidizing annealing.
3) Poor spheroidizing annealing process, such as too high or too low annealing temperature and short isothermal annealing time, can cause uneven microstructure or poor spheroidizing.
(2) Preventive measures
1) Generally, H13 die steel with good quality should be selected according to the working conditions of the die, the production batch and the strength and toughness of the material itself.
2) In order to eliminate the inhomogeneity of network and chain carbides and carbides in raw materials, the forging process is improved or normalizing heat treatment is adopted.
3) Solution refining heat treatment can be used for high carbon die steel with severe carbide segregation which can not be forged.
4) To make correct spheroidizing annealing process specification for forged die blank, quenching and tempering heat treatment and rapid uniform spheroidizing annealing can be used.
5) Reasonable charging can ensure the temperature uniformity of mould billet in the furnace.
3. Quenching crack of mould
The crack of H13 die steel after quenching is the biggest defect in the process of die heat treatment, which will scrap the processed die and cause great loss in production and economy.
(1) Causes
1) There is serious network carbide segregation in H13 die steel.
2) There are mechanical or cold plastic deformation stresses in the die.
3) Improper operation of mold heat treatment (too fast heating or cooling, improper selection of quenching medium, too low cooling temperature, too long cooling time, etc.).
4) The complex shape, uneven thickness, sharp angle and threaded hole of the die result in excessive thermal stress and microstructure stress.
5) Overheating or overburning occurs when the heating temperature of die quenching is too high.
6) Tempering is not timely or holding time is not enough after quenching.
7) When the die is repaired and quenched, it is reheated and quenched again without intermediate annealing.
8) The heat treatment of the mould is poor and the grinding process is improper.
9) There are high tensile stress and microcracks in the hardened layer during EDM after heat treatment.
(2) Preventive measures
1) Strictly control the internal quality of raw materials for die steel
2) The forging and spheroidizing annealing processes were improved to eliminate network, band and chain carbides and improve the uniformity of spheroidizing structure
3) The die after machining or cold plastic deformation should be annealed (> 600 ℃) and then quenched.
4) For the mould with complex shape, asbestos should be used to plug the threaded hole, wrap the dangerous section and thin wall, and adopt the step quenching or isothermal quenching.
5) Annealing or high temperature tempering is required when repairing or renovating the mould.
6) The mould should be preheated during quenching and heating, precooling measures should be taken during cooling, and suitable quenching medium should be selected.
7) The heating temperature and time of quenching should be strictly controlled to prevent the die from overheating and overburning.
8) After quenching, the die should be tempered in time, the holding time should be sufficient, and the high alloy complex die should be tempered 2-3 times.
9) Choose the right grinding process and grinding wheel.
10) The die EDM process was improved and stress relief tempering was carried out.
4. The structure of the die is coarse after quenching
After quenching, the structure of the die is coarse, which will seriously affect the mechanical properties of the die. When the die is used, it will fracture and seriously affect the service life of the die.
(1) Causes
1) The actual quenching temperature of die steel is far lower than that of required die material (for example, GCr15 steel is regarded as 3Cr2W8V steel).
2) The correct spheroidizing process was not carried out before quenching of die steel, resulting in poor spheroidizing structure.
3) The heating temperature of die quenching is too high or the holding time is too long.
4) If the mould is not placed properly in the furnace, it is easy to overheat in the area near the electrode or heating element.
5) For the die with large cross-section variation, improper selection of quenching and heating process parameters leads to overheating at thin cross-section and sharp corner.
(2) Preventive measures
1) The steel products should be inspected strictly before they are put into storage to prevent them from being mixed up.
2) Correct forging and spheroidizing annealing should be carried out before quenching to ensure good spheroidizing structure.
3) The quenching and heating process specification should be established correctly, and the quenching and heating temperature and holding time should be strictly controlled.
4) Check and calibrate the temperature measuring instrument regularly to ensure the normal operation of the instrument.
5) When the mould is heated in the furnace, it should keep a proper distance from the electrode or heating element.

Metal(Steel) machining

Metal manufacturing involves many processes, one of which is processing, which is a necessary requirement of modern large-scale manufacturing. The machine cuts, drills, grinds or otherwise shapes the metal by removing some of the metal using a cutting or grinding surface. Generally, the machine tool has two parts: one part holds and guides the metal to be formed, and the other part completes the forming work. Machining, especially in the computer age, can carry out accurate and fine metal processing.

Casting, forging and machining
There are several main forms of creating metal shapes.
Casting is the process of filling a mold with molten alloy and cooling it. Forging metal can change the properties of materials by applying compressive force to change the metal lattice. Bending, twisting, impact and folding operations are common in forging. To machine, carve, grind, cut, drill, or otherwise mold metal. The way a mechanic handles metal is similar to the way a carpenter handles wood; Although the shape and finish have been processed, most of the materials have not changed.
In modern times, machining is usually the finishing step of forging or casting products, in order to make the forging or casting objects reach the precision tolerance range. Milled plates, blanks and bars can also be machined from their original geometry.
Casting and forging usually occur before machining. The processed object may be further processed before the metal object is finished. Workpieces can be connected by fasteners or welds, heat treated, or other surface treatment.

What is CNC machining? Machining tool steel
CNC stands for computer numerical control. In CNC machine, the computer precisely controls the movement of the machine. The design generated in CAD software is converted to motion on X, y and Z axes. In this way, a computerized machining shop can carve metal in three dimensions with precise tolerances.

Commonly used machine tools are as below:
Lathe – turning the metal work against the cutting tool,

Drilling machine – pushing the drill through the metal surface

Grinder – turning the abrasive or grinder against the metal work,

Belt machine – cutting the metal work with a continuous saw blade,

Milling machine – shaping the metal work on the surface with a rotary cutting tool,

Broaching machine – filing objects, only remove a small amount of material

Laser cutting and etching – beams used to cut, drill or etch objects

Ultrasonic machining – Ultrasonic and abrasive slurries to remove metal

Electron beam machining – a beam of electrons generates high heat and vaporizes metal

Chemical and electrochemical methods – use chemicals to remove and shape metal

Lathe is the ancestor of many machine tools. The lathe rotates the object against the edge of the cutting tool. Therefore, the lathe can be used for boring, drilling, thread cutting, milling and grinding: as long as it can turn metal products, the lathe can replace other tools.