Information on alloy elements and associated elements (part 2)

9- (Cr)Chrome

Melting point is 1920 ° C
The presence of chromium in steel makes it hardened in oil and air.
By reducing the critical cooling rate in order to martensize its crystalline structure, the presence of chromium metal increases the hardness and thereby improves the ability to improve steel. Reduces the toughness of the impact and reduces the relative length to very low proportions. By increasing the chromium content in pure chrome steels, welding ability decreases. For each 1% chromium, the tensile strength increases by 80-100 N / mm2.
Chrome is a carbide maker element. Chrome carbide increases the shear strength and toughness of steel. The heat and compression strength of hydrogen under pressure is enhanced by chromium metal. In addition, with a high percentage of chromium, the crust resistance increases, but to produce corrosion resistance of steels, a percentage of this element is needed at least 13% that needs to be solved in the field.
This element narrows the y-domain and, on the contrary, broadens the ferrite domain. This element also stabilizes austenite in austenitic steels of chromium-manganese or chromium-nickel.
The thermal and electrical conductivity, as a result of the presence of this element, decreases and the thermal expansion also drops (special molten glass alloys).
As the carbon element increases, the amount of this element increases up to 3% of the phenomena, such as magnetic resistivity and residual force.

10- (Cu)Copper

Melting point is 1084 degrees Celsius
Copper is only used in a small number of steels as an alloying element because the metal is susceptible to the surface of steel due to its local focusing under the steel shell and penetrating the grain boundary at the hot forming stages, which is why in some cases This element can be regarded as detrimental.
offset yield strength and offset yield strength ratio – strength is increased. More than 0.3% of this element is effective on the aging properties of steel. Hardness is improved. The presence of copper is unaffected by the ability of steel welding.
Resistance to atmospheric agents of non-alloy and low-alloy steels is considerably improved by adding copper to them. If the amount of copper in an acid-resistant alloy is higher than 1%, it will improve its resistance to hydrochloric acid and sulfuric acid.

11- (H)Hydrogen

Melting point -262 degrees Celsius
Due to the fact that this element, without increasing offset yield strength and tensile strength, reduces the elongation of the relative length and reduces the cross-section of the steel and makes it fragile, it is one of the harmful elements for the steel. Hydrogen is the main factor and the improvement of the formation of the line of agglomeration. When hydrogenation occurs, hydrogen penetrates the steel by formation of bubbles.
Wet hydrogen, at high temperatures, causes de-carbonation.

12- (Mg)magnesium

Melting point 657 ° C
The presence of this element makes the formation of spherical graphite in cast iron without any form.

13- (Mn)Manganese

Melting point 1221 ° C
Manganese is a deoxidizing element. With sulfur, it forms a manganese sulfide and thereby neutralizes the effect of iron sulfide. In automate steel (auto) it is an important alloying element because it reduces the risk of hot brittleness.
The critical cooling rate is greatly reduced and thus the hardness of the steel is increased. offset yield strength and steel strength increased with the addition of increased manganese, forging ability and welding ability is improved, and greatly increased the hardness depth of the steel.
The content of more than 4% of this element, despite the low cooling rate, causes a martensitic brittleness so that the alloying sphere is rarely used.
Steel with a manganese content of more than 12%, despite the high amount of carbon, is austenite type, because the manganese element strongly expands the Y domain. If the surface of such steels is subjected to stresses, their surface hardness increases, but their brains remain stiff. Therefore, such steels have a very high abrasion resistance against beats loads.
steels with a manganese of more than 18% can not be magnetized if they have a high deformation percentage and are used as special steels as well as have application of cold stiffened steels in low temperature loading.
The thermal expansion coefficient increases with increasing manganese but decreases the thermal and electrical conductivity..

14- (Mo)Molybdenum

Melting point 2622 ° C
Usually this metal is used with some other alloying elements. By reducing the critical cooling time by this element, the hardness will improve.
Molybdenum reduces temper brittleness, for example, in chromium-nickel steel and manganese steels, causing fine crystallization of the structure and the ability to weld at optimum levels. offset yield strength and tensile strength increase. If the molybdenum content is higher than a certain amount, steel forging will be harder. It is a carbide element and improves the shear properties of the high speed steels.
This metal is considered to be an element that increases the resistance to rusting, and is thus used in chromium-plated steel and also in chromium-nickel austenitic steels. A high percentage of molybdenum leads to a reduction in pitting corrosion. It narrows the Y area, increases the thermal strength of the steel and reduces the crust resistance.The thermal expansion coefficient increases with increasing manganese but decreases the thermal and electrical conductivity..

15- (N)Nitrogen

Melting point is -10 ° C
This element can also be considered as one of the harmful elements and as one of the alloying elements of steel.
Harmful in the view that due to the phenomenon of detachment reduces toughness and sensitization against aging, the brittleness of the blue (forming in the range of darkness of 350 ° C to 300 ° C) in steel and the possibility of dissolution between the crystalline corrosion – stress Tensile non-alloy and low-alloy steels.
Harmful in the view that due to the phenomenon of detachment reduces toughness and sensitization against aging, the brittleness of the blue (forming in the blue thermal range temperature of 350 ° C to 300 ° C) is created in steel and allows for the dissolution between crystalline corrosion – the tensile stress of non-alloy and low-alloy steels.
The y domain becomes better and stabilizes the crystalline structure of the steel, enhances the austenitic steels strength, and in particular increases the offset yield strength and the mechanical properties of the steel in the heat. It is one of the elements in nitride synthesis and thus increases the surface hardness of the steels in the nitriding step.

This post is also available in: فارسی (Persian)

welcome to website, Fidar Maham Pishro company



برای چت در واتس اپ بر روی گزینه پشتیبانی کلیک نمایید و یا درصورت تمایل می توانید به آدرس  ایمیل ارسال نمایید.

× چگونه می‌توانم به شما کمک کنم؟