What is the difference between 45 and 40Cr? Difference Between 40cr and 42crmo:

45 is a high-strength medium carbon quenched and tempered steel, with a certain plasticity and toughness, high strength, good cutting performance, but its welding performance is low, it should be preheated before welding, annealed after welding. The CR content is less than or equal to, and it is suitable for higher strength moving parts, such as air compressors, impellers, gears, etc.

35CR is a medium carbon alloy quenched and tempered steel, with higher strength and toughness, better than 45, and is used to manufacture various parts that are wear-resistant or impacted, such as rollers, bolts, etc.

40CR is also alloy steel, which has good comprehensive mechanical properties after quenching and tempering, and is one of the most widely used steel grades, used to manufacture medium-speed and medium-load parts, such as machine tool gears, shafts, worms, spline shafts, etc., it can replace 40mnb, 45mnb, 35simn, 42simn, 40mnvb and so on. Reference.

The carbon content of 45 steel and 40cr is different, one is 45 parts per ten,000 and the other is 40 parts per thousandThe second is that the CR content is different. The CR content of 40CR is high, so it is deliberately labeled. CR can increase the hardenability of steel heat treatment. Nothing else makes much difference.

45 The amount of carbon (C) in the chemical composition is, Si content, Mn content, Cr content, Ni content. , Cu content.

40cr chemical composition (mass fraction, %)c.

1. The concept is different.

40CR is an alloy structural steel, which is based on the high-quality carbon structural steel No. 40, with the appropriate addition of CR elements, after quenching and tempering, it has good comprehensive properties, low temperature impact toughness and low notch sensitivity.

45 steel belongs to high-quality carbon structural steel, commonly known as excellent steel, this steel does not contain specially included alloying elements, 45 steel is the most widely used high-quality structural steel.

2. The performance is different.

The hardenability of 40cr steel is good, it can be hardened to 28 60mm when water quenched, and 15 40mm when quenched by oil. In addition to quenching and tempering, this steel is also suitable for cyanide and high-frequency quenching. The machinability is good, when the hardness is 174 229HB, the relative machinability is 60%.

The steel is suitable for medium-sized plastic molds.

45 steel cold plasticity is general, annealing, normalizing is slightly better than quenching and tempering, with higher strength and good machinability, after appropriate heat treatment can obtain a certain toughness, plasticity and wear resistance, the material is convenient. It is suitable for hydrogen welding and argon arc welding, and is not very suitable for gas welding. Preheating is required before welding, and stress relief annealing should be carried out after welding.

3.Different uses.

40CR is one of the most widely used steel grades, quenched and tempered for the manufacture of medium-speed, medium-load parts, such as machine tool gears, shaft worms, spline shafts, center sleeves, etc., quenched and tempered and high-frequency induction hardening for the manufacture of high-hardness, wear-resistant parts on the surface, such as gears, shafts, spindles, crankshafts, mandrels, sleeves, pins, connecting rods, screws, nuts, intake valves, etc.

45 steel is suitable for the manufacture of higher strength moving parts, such as air compressors, pump pistons, steam turbine impellers, rolled shafts, connecting rods, worms, racks, gears, pins, etc. in heavy and general machinery.

4.The chemical composition is different.

40cr chemical content.

C: 45 steel chemical composition.

c： si ： mn： cr ：≤ni ：≤cu ：≤

5.The mechanical properties are different.

40cr mechanical properties.

Tensile strength: 980MPa, yield strength: 785MPa, elongation after breaking: 9%, expansion and contraction rate after breaking: 45%, impact absorption work: 47J.

45. Mechanical properties of steel.

Tensile strength: 600MPa, yield strength: 355MPa, elongation after fracture: 16%, section shrinkage: 40%, impact absorption energy: 39J

Hello! Differences: These two materials are medium carbon alloy quenched and tempered steel; Its carbon content is medium carbon, there are different alloying elements, quenching heating temperature is basically similar, but quenching heat preservation time and tempering process are different, the key is to look at the wall thickness of the hot part, the required mechanical properties, so as to determine which material should be used in the two materials, and quenching cooling method and tempering process.

Differences: 1) Differences in alloying elements: The alloying elements contained in 42CrMo materials are Cr and Mo, both of which can improve the hardenability of the material, but the hardenability of Mo elements is much greater than that of Cr elements, and Mo elements can refine grains and resist the second type of tempering brittleness.

2) The difference in quenching and heat preservation time: due to the addition of MO element, the quenching and heat preservation time can be appropriately extended to fully alloy and homogenize the austenite, so that the martensite obtained by quenching has high enough strength. 3) The difference between tempering heating temperature and holding time:

Due to the addition of MO element, the anti-tempering stability of the material is increased, that is, the alloy martensite containing MO is not easy to decompose at the same tempering temperature, so the tempering temperature can be increased accordingly, and the holding time of tempering is also extended accordingly. 4) The difference in mechanical properties of the first circle:

The differences between 42CRMO and 40CR are as follows:

1. The metal content is different.

40cr has carbon and inscription elements, and no molybdenum elements. 42CrMo has carbon elements, and the content is the same as 40Cr, including inscription and molybdenum.

2. The pressure-bearing capacity is different.

The compressive strength of 40cr is 800MPa, the yield point is 1000MPa, and the yield point is 950MPa.

The main matters of quenching and tempering treatment of 42CRMO:

1. The speed of the workpiece from the heating furnace to the cooling tank is slow, and the temperature of the workpiece into the water has dropped to below the critical point of Ar3, resulting in partial decomposition, and the workpiece gets an incomplete quenching structure, which cannot meet the hardness requirements. Therefore, the coolant of small parts should pay attention to the speed, and the time of cooling of large workpieces should be mastered.

2. The amount of workpiece loading should be reasonable, 1 2 layers is appropriate, and the workpieces overlap each other to cause uneven heating, resulting in uneven hardness.

3. The workpiece should be kept at a certain distance from the water arrangement, and the steam film near the workpiece will be blocked by too denseness, resulting in low hardness on the close surface of the workpiece.

4. Opening the furnace for quenching, can not be quenched in one go, should be depending on the degree of furnace temperature drop, close the furnace halfway and re-heat, so that the workpiece after quenching the hardness is consistent.

5. Pay attention to the temperature of the coolant, the coolant can not have oil, mud and other impurities, otherwise, there will be insufficient hardness or unevenness.

6. Unprocessed blank quenching and tempering, hardness will not be uniform, if you want to get good quenching and tempering quality, the blank should be rough turning, and the bar material should be forged.

7. Strictly control the quality, the hardness is 1 3 units lower after quenching, and the tempering temperature can be adjusted to meet the hardness requirements. However, the hardness of the workpiece after quenching is too low, and some even only HRC25 35, must be re-quenched, and must not only be tempered at medium or low temperature to achieve the requirements of the drawing, otherwise, the meaning of quenching and tempering will be lost, and serious consequences may occur. <>

First of all, ask where you saw this.

40Cr is the standard steel number of GB in China, and 40Cr steel is one of the most widely used steels in the machinery manufacturing industry. After quenching and tempering treatment, it has good comprehensive mechanical properties, good low-temperature impact toughness and low notch sensitivity. The hardenability of steel is good, it can be hardened up to 28 60mm when water quenched and 15 40mm when oil quenched.

In addition to quenching and tempering, this steel is also suitable for cyanide and high-frequency quenching. The machinability is good, when the hardness is HB174 229, the relative machinability is 60%. The steel is suitable for medium-sized plastic molds.

40cr is a grade of special steel, which is the main material of mechanical parts.

Introduction to CR4 alloy structural steel:

41Cr4 (is the most commonly used grade of alloy structural steel in the world. Its tensile strength, yield strength and hardenability are higher than that of No. 40 steel, but it also has certain defects that its weldability is limited and has a tendency to form cracks. 41Cr4 is generally used for more important quenched and tempered parts, such as parts working under alternating load, parts with medium speed and medium load, etc.

2. Alloy structural steel:

On the basis of carbon structural steel, appropriate alloying elements are added, which are mainly used to manufacture steel for mechanical parts with large cross-sectional dimensions. It has suitable hardenability, high strength, toughness and fatigue strength after corresponding heat treatment, and low brittle transition temperature. This type of steel mainly includes quenched and tempered steel, case-hardened steel, and cold-plastic formed steel.

CR4 standard: EN 10083 1-1991 standard.

CR4 Delivery Condition: Delivered in heat-treated (normalized, annealed or high-temperature tempered) or non-heat-treated. PS: If the customer has other performance requirements, the delivery status requirements should be indicated in the contract.

Cr4 chemical composition (elemental composition: wt%):

Carbon C : Silicon Si: Permissible residual content

Manganese Mn: Sulphur S: Allowable residual content

Phosphorus p: permissible residual content of chromium cr:

Nickel Ni: Permissible Residual Content Copper Cu: Permissible Residual Content

PS: The specific chemical composition should be indicated in the steel mill material book.

Mechanical properties of CR4:

Tensile Strength b (MPa): 980(100) Yield Strength S (MPa): 785(80).

Elongation δ5 (%9 cross-sectional shrinkage 45

Impact power AKV (J): 47 Impact toughness value KV (j cm2): 59(6).

Hardness : 207HB

Specimen size: The specimen blank size is 25mm

PS: The specific mechanical properties should be indicated in the material book of the steel mill.

Application and use of CR4:

41CR4 is used for more important quenched and tempered parts, such as parts working under alternating loads, parts with medium speed and medium load. After surface quenching, it can be used for parts with high load and wear resistance without great impact, such as gears, sleeves, shafts, crankshafts, and pins.