MEIF理財部落格

21 Chemical Elements and Effects on Steel Mechanical Properties

If you are in steel industry, have you ever notice what all those chemical composition listed on a steel materials test report really mean? You may only know different steel grade has many different chemical composition and elements in different amount. Here in this post, we sort out and list 21 chemical elements and effects on steel properties.

21 Chemical Elements and Effects on Steel Mechanical Properties

Steel in general is an alloy of carbon and iron, it does contain many other elements, some of which are retained from the steel making process, other elements are added to produce specific properties. We can see some most common chemical elements with important effects on steel properties.

 1. Carbon (C)

Carbon is the most important element in steel, it is essential in steels which have to be hardened by quenching and the degree of carbon controls the hardness and strength of the material, as well as response to heat treatment (hardenability).
And ductility, forgeability and machinability will decrease if the amount of carbon increases, as well as weldability properties of the steel.

 2. Manganese (Mn)

Manganese could be the second most important element after Carbon on steel. Mn has effects similar to those of carbon, and the steel producer uses these two elements in combination to obtain a material with the desired properties. Manganese is a necessity for the process of hot rolling of steel by its combination with oxygen and sulfur.

Its presence has below main effects:

    It is a mild deoxidant acting as a cleanser taking the sulphur and oxygen out of the melt into the slag.
    It increases the harden ability and tensile strength but decreases ductility.
    It combines with sulphur to form globular manganese sulphides, essential in free cutting steels for good machinability.

Steels usually contain at least 0.30% manganese, however, amounts of up to 1.5% can be found in some carbon steels.

Manganese also tends to increase the rate of carbon penetration during carburizing and acts as a mild deoxidizing agent. However when too high carbon and too high manganese accompany each other, embrittlement sets in. Manganese is capable to form Manganese Sulphide (MnS) with sulphur, which is beneficial to machining. At the same time, it counters the brittleness from sulphur and is beneficial to the surface finish of carbon steel.

For welding purposes, the ratio of manganese to sulphur should be at least 10 to 1. Manganese content of less than 0.30% may promote internal porosity and cracking in the weld bead, cracking can also result if the content is over 0.80%. Steel with low Manganese Sulphide ratio may contain sulphur in the form of iron Sulphide (FeS), which can cause cracking in the weld.

3. Phosphorus (P)

Although it increases the tensile strength of steel and improves machinability it is generally regarded as an undesirable impurity because of its embrittling effect.

Effect of phosphorus element will have various effects on steel depending on concentration.
The maximum amount of phosphorus in higher grade steel is between 0.03 to 0.05% due to the fact that is detrimental. Up to 0.10% of phosphorus in low-alloy high-strength steels will increase the strength as well as improve the steel's resistance against corrosion. The possibility of brittlement increases when the content in hardened steel is too high. Even though the strength and hardness is improved, the ductility and toughness decreases.

The machinability is improved in free-cutting steel, but weld brittle and/or weld cracks can occur during welding if the phosphorus content is more than 0.04%. Phosphorus also affects the thickness of the zinc layer when galvanising steel.

4. Sulfur (S)

Sulfur is normally regarded as an impurity and has an adverse effect on impact properties when a steel is high in sulphur and low in manganese. Sulphur improves machinability but lowers transverse ductility and notched impact toughness and has little effects on the longitudinal mechanical properties. Its content is limited to 0.05% in steels but is added to free cutting steels in amount up to 0.35% with the manganese content increased to counter any detrimental effects since alloying additions of sulfur in amounts from 0.10% to 0.30% will tend to improve the machinability of a steel. Such types may be referred to as "resulfurized" or "freemachining". Free cutting steels have sulphur added to improve machinability, usually up to a maximum of 0.35%.

Even though the effect of sulphur on steel is negative at certain stages, any sulphur content less than 0.05% has a positive effect on steel grades.

5. Silicon (Si)

Silicon is one of the principal deoxidizers for steel. Silicon helps to remove bubbles of oxygen from the molten steel. It is the element that is most commonly used to produce semi- and fully killed steels, and normally appears in amounts less than 0.40 percent, usually only small amounts (0.20%) are present in rolled steel when it is used as a deoxidizer. However, in steel castings, 0.35 to 1.00% is commonly present.

Silicon dissolves in iron and tends to strengthen it. Some filler metals may contain up to 1% to provide enhanced cleaning and deoxidation for welding on contaminated surfaces. When these filler metals are used for welding on clean surfaces, the resulting weld metal strength will be markedly increased. Silicon increases strength and hardness but to a lesser extent than manganese. The resulting decrease in ductility could resent cracking problems.

For galvanizing purposes, steels containing more than 0.04% silicon can greatly affect the thickness and appearance of the galvanized coating. This will result in thick coatings consisting mainly zinc-iron alloys and the surface has a dark and dull finish. But it provides as much corrosion protection as a shiny galvanized coating where the outer layer is pure zinc.

6. Chromium (Cr)

Chromium is a powerful alloying element in steel. Cr presents in certain structural steels in small amounts. It is primarily used to increase hardenability of steel and increase the corrosion resistance as well as the yield strength of the steel material. For that reason often occurs in combination with nickel and copper. Stainless steels may contain in excess of 12% chromium. The well-known “18-8” stainless steel contains 8 percent of nickel and 18 percent of chromium.

When the percent of chromium in the steel exceeds 1.1% a surface layer is formed that helps protect the steel against oxidation.

7. Vanadium (V)

The effects of Vanadium chemical element are similar to those of Mn, Mo, and Cb. When used with other alloying elements it restricts grain growth, refines grain size, increases hardenability, fracture toughness, and resistance to shock loading. Softening at high temperatures, fatigue stress and wear resistance are improved. At greater than 0.05%, there may be a tendency for the steel to become embrittled during thermal stress relief treatments.

Vanadium is used in nitriding, heat resisting, tool and spring steels together with other alloying elements.

8. Tungsten (W)

It is used with chromium, vanadium, molybdenum, or manganese to produce high speed steel used in cutting tools. Tungsten steel is said to be "red-hard" or hard enough to cut after it becomes red-hot.
After heat treatment the steel maintains its hardness at high temperature making it particularly suitable for cutting tools.

Tungsten in the form of tungsten carbide

• Gives steel high hardness even at red heats.
• Promotes fine grains
• Resists heat
• Promote strength at elevated temperatures

9. Molybdenum (Mo)

Molybdenum has effects similar to manganese and vanadium, and is often used in combination with one or the other. This element is a strong carbide former and is usually present in alloy steels in amounts less than 1%. It increases hardenability and elevated temperature strength and also improves corrosion resistance as well as increased creep strength. It is added to stainless steels to increase their resistance to corrosion and is also used in high speed tool steels.

10. Cobalt (Co)

Cobalt improves strength at high temperatures and magnetic permeability.

Increases hardness, also allows for higher quenching temperatures (during the heat treatment procedure). Intensifies the individual effects of other elements in more complex steels. Co is not a carbide former, however adding Cobalt to the alloy allows for higher attainable hardness and higher red hot hardness.

11. Nickel (Ni)

In addition to its favorable effect on the corrosion resistance of steel, Ni is added to steels to increase hardenability. Nickel enhances the low-temperature behavior of the material by improving the fracture toughness. The weldability of the steel is not decreased by the presence of this element. The nickel drastically increases the notch toughness of the steel.

Nickel is often used in combination with other alloying elements, especially chromium and molybdenum. It is a key component in stainless steels but at the low concentrations found in carbon steels. Stainless steels contain between 8% and 14% nickel.

One more reason Ni is added to an alloy is that it creates brighter portions in damascus steels.

12. Copper (Cu)

Copper is another primary corrosion resistance elements. It also has a small impact on hardenability. It is typically found in amounts not less than 0.20 percent, and is the primary anti-corrosion component in steel grades like A242 and A441.

Most often found as a residual agent in steels, copper is also added to produce precipitation hardening properties and increase corrosion resistance.

13. Aluminum (Al)

Aluminum is one of the most important deoxidizers in very small amounts in the material, and also
helps form a more fine-grained crystalline microstructure and increase the steel grade’s toughness. It is usually used in combination with silicon to obtain a semi- or fully killed steel.

14. Titanium (Ti)

Ti is used to control grain size growth, which improves toughness. Also transforms sulfide inclusions form elongated to globular, improving strength and corrosion resistance as well as toughness and ductility.

Ti is a very strong, very lightweight metal that can be used alone or alloyed with steels. It is added to steel to give them high strength at high temperatures. Modern jet engines used titanium steels.

• It prevents localized depletion of chromium in stainless steels during long heating
• Prevents formation of austenite in high chromium steels
• Reduces martensitic hardness and hardenability in medium chromium steels.

15. Niobium(Nb, formerly known as Columbium-Columbium, Cb )

Niobium is a key grain refining element, as well a strength-enhancing elements in steel production. Niobium is a strong carbide former and forms very hard, very small, simple carbides. Improves ductility, hardness, wear and corrosion resistance. Also, refines grain structure. Formerly known as Columbium.

16. Boron (B)

The most important effect and the purpose of boron in steel is to drastically improve the hardenability.

The biggest advantage of boron is that a small amount can be added to get the same result as other elements required in large amount in terms of added hardenability. Typical range in steel alloys is 0.0005 to 0.003%.

During the heat treatment process boron, a replacement for other elements, is added to increase the hardenability of medium carbon steel. The cutting performance for high-speed steels is increased but at the expense of the forging quality. It is also possible that the content of boron can be too high which decreases hardenability, toughness as well as cause embrittlement. The percentage carbon present in the steel also plays a role in the hardenability effect of boron. As boron's effect on hardenability increases the amount of carbon should proportionally be decreased.

When boron is added to steel, precaution must be taken to ensure that it does not react with oxygen or nitrogen as the combination of boron with either one of the two will make the boron useless.

17. Lead (Pb)

The addition of lead in levels in very small amounts to improve machinability, up to 0.30%, improves machinability. Providing the distribution is homogenous it has little effect on the physical properties of the steel, and contrary to popular belief, it does not affect weld ability.

18. Zirconium (Zr)

Zirconium is added to steel to modify the shape of inclusions. Typically added to low alloy, low carbon steels. The result is that toughness and ductility are improved when transforms shape from elongated to globular, improving toughness and ductility.

19. Tantalum (Ta)

Chemically very similar to Niobium (Nb), as such, has similar effect on the alloy - forms very hard, very small, simple carbides. Improves ductility, hardness, wear and corrosion resistance. Also, refines grain.

20. Nitrogen (N)

Nitrogen acts very similar to Carbon in the alloy. N substitutes C in small amounts (or even large, with modern technologies) to increase hardness. Obviously, Nitrogen forms Nitrides, not Carbides. INFI has N, and there's few more, with Sandvik being the champion, having 3% N in the alloy, completely substituting C. Sadly, not available for knife makers. Because Nitrogen is less prone to form Chromium nitrides than Carbon is to form Chromium carbides, its presence improves corrosion resistance, leaving more free Chromium in the alloy. Since Nitrogen is less reactive in forming Nitrides, it can be used for added hardness without increasing carbide size and volume, e.g. Sandvik 14C28N steel.

21. Selenium (Se)

Typically not desirable in cutlery steel. Added to improve machinability. Similar with Sulfur, in the same chalcogen group.

All chemical elements and effects shown above is related in steel materials. So, if you are in the steel industry, you should same it.

There are some other small rare metal elements which we don’t list in the above. You could leave a comment below, with details.

如果您從事鋼鐵行業，您是否注意到鋼鐵材料測試報告中列出的所有化學成分的真正含義是什麼？您可能只知道不同等級的鋼具有許多不同的化學成分和元素。在本文中，我們整理並列出了21種化學元素及其對鋼性能的影響。

21化學元素及其對鋼力學性能的影響

鋼通常是碳和鐵的合金，它確實包含許多其他元素，其中一些是從煉鋼過程中保留下來的，添加其他元素以產生特定的性能。我們可以看到一些對鋼性能有重要影響的最常見的化學元素。

 1.碳（C）

碳是鋼中最重要的元素，在必須通過淬火硬化的鋼中是必不可少的，碳的程度控制著材料的硬度和強度，以及對熱處理（可淬性）的響應。
如果碳含量增加，延展性，可鍛性和可切削性將降低，同時鋼的可焊性也將降低。

 2.錳（Mn）

錳可能是僅次於鋼的碳的第二重要元素。 Mn具有與碳相似的作用，鋼鐵生產商將這兩種元素結合使用可獲得具有所需性能的材料。錳是鋼與氧氣和硫結合的熱軋工藝的必要條件。

它的存在具有以下主要作用：

    它是一種溫和的脫氧劑，可作為清潔劑，將硫和氧從熔體中帶入爐渣。
    它增加了硬化能力和拉伸強度，但降低了延展性。
    它與硫結合形成球狀硫化錳，這對於易切削鋼具有良好的切削性至關重要。

鋼通常含有至少0.30％的錳，但是，在某些碳鋼中，錳的含量最高可達1.5％。

錳還傾向於增加滲碳過程中碳的滲透速率，並起緩和脫氧劑的作用。但是，當碳含量太高和錳含量太高時，脆化就會發生。錳能夠與硫形成硫化錳（MnS），這有利於機加工。同時，它可抵禦硫的脆性，有利於碳鋼的表面光潔度。

出於焊接目的，錳與硫的比例應至少為10：1。錳含量低於0.30％可能會促進內部氣孔和焊縫開裂，如果含量超過0.80％，也會導致開裂。硫化錳比例低的鋼可能會以硫化鐵（FeS）的形式包含硫，這可能會導致焊縫開裂。

3.磷（P）

儘管它增加了鋼的抗拉強度並改善了可切削性，但由於其脆化作用，通常被認為是不希望有的雜質。

磷元素的影響取決於濃度對鋼有各種影響。
由於有害的事實，高級鋼中的最大磷含量在0.03至0.05％之間。低合金高強度鋼中的磷含量高達0.10％，將提高強度並提高鋼的耐腐蝕性。當淬火鋼中的含量太高時，脆化的可能性就會增加。即使強度和硬度提高，延展性和韌性也會降低。

易切削鋼的切削加工性得到改善，但是如果磷含量超過0.04％，則在焊接過程中會發生焊縫脆性和/或焊縫裂紋。鍍鋅時，磷也會影響鋅層的厚度。

4.硫（S）

當鋼中的硫含量高而錳含量低時，硫通常被認為是雜質，並且對沖擊性能產生不利影響。硫改善了可加工性，但降低了橫向延展性和缺口衝擊韌性，對縱向機械性能影響很小。它在鋼中的含量限制為0.05％，但以不超過0.35％的含量添加到易切削鋼中，而錳的含量則可以抵消任何不利影響，因為從合金中添加0.10％至0.30％的硫會改善合金的硫含量。鋼的機械加工性。這樣的類型可以被稱為“再硫化”或“自由加工”。易切削鋼中添加了硫以提高可加工性，通常最高可達0.35％。

即使在某些階段硫對鋼的影響是負面的，但任何低於0.05％的硫含量都會對鋼種產生正面影響。

5.矽（Si）

矽是鋼的主要脫氧劑之一。矽有助於去除鋼水中的氧氣氣泡。它是最常用於生產半鎮靜鋼和全鎮靜鋼的元素，通常以少於0.40％的量出現，當用作脫氧劑時，軋製鋼中通常只存在少量（0.20％）。然而，在鋼鑄件中，通常存在0.35％至1.00％。

矽溶解在鐵中並趨於增強。某些填充金屬含量可能高達1％，以提供增強的清潔和脫氧性，以在污染的表面上進行焊接。當這些填充金屬用於清潔表面的焊接時，所得到的焊接金屬強度將顯著提高。矽增加強度和硬度，但程度不及錳。延展性的下降可能會引起裂紋問題。

為了鍍鋅，含矽量超過0.04％的鋼會極大地影響鍍鋅層的厚度和外觀。這將導致主要由鋅鐵合金組成的厚塗層，並且表面具有深色和暗淡的光潔度。但是，與外層為純鋅的鍍鋅塗層一樣，它提供的腐蝕防護也一樣多。

6.鉻（Cr）

鉻是鋼中強大的合金元素。 Cr在某些結構鋼中的含量很少。它主要用於提高鋼的淬透性，並提高鋼材的耐腐蝕性以及屈服強度。因此，常與鎳和銅結合使用。不銹鋼可能含有超過12％的鉻。著名的“ 18-8”不銹鋼包含8％的鎳和18％的鉻。

當鋼中鉻的百分比超過1.1％時，會形成有助於保護鋼免於氧化的表面層。

7.釩（V）

釩化學元素的作用與Mn，Mo和Cb相似。當與其他合金元素一起使用時，它會限制晶粒長大，細化晶粒尺寸，提高淬透性，斷裂韌性和抗衝擊負荷能力。高溫下的軟化，疲勞應力和耐磨性得到改善。大於0.05％時，在熱應力消除處理中鋼可能會變脆。

釩與其他合金元素一起用於氮化，耐熱，工具和彈簧鋼。

8.鎢（W）

它與鉻，釩，鉬或錳一起使用以生產用於切削工具的高速鋼。據說鎢鋼是“紅硬的”，或者在變紅後足以切割。
熱處理後，鋼在高溫下保持其硬度，使其特別適合於切削工具。

碳化鎢形式的鎢

    即使在高溫下也能賦予鋼高硬度。
    促進穀物
    抗熱
    在高溫下增強強度

9.鉬（Mo）

鉬具有類似於錳和釩的作用，並且經常與一種或另一種結合使用。該元素是強碳化物形成劑，通常在合金鋼中的含量少於1％。它增加了淬透性和高溫強度，還改善了耐腐蝕性以及蠕變強度。它被添加到不銹鋼中以提高其耐腐蝕性，也用於高速工具鋼。

10.鈷（Co）

鈷提高了高溫強度和磁導率。

增加硬度，還允許更高的淬火溫度（在熱處理過程中）。增強了更複雜鋼中其他元素的個體作用。 Co不是碳化物形成劑，但是向合金中添加鈷可以實現更高的可達到的硬度和更高的紅熱硬度。

11.鎳（Ni）

除了對鋼的耐腐蝕性具有有利的作用之外，Ni還被添加到鋼中以提高淬透性。鎳增強了合金的低溫性能

12.銅（Cu）

銅是另一種主要的耐腐蝕元素。它對可淬性的影響也很小。通常發現其含量不少於0.20％，是A242和A441等鋼種的主要防腐成分。

最常見的是作為鋼中的殘留劑，還添加了銅以產生沉澱硬化性能並提高耐腐蝕性。

13.鋁（Al）

鋁是材料中最重要的最重要的脫氧劑之一，而且
有助於形成更細的晶體顯微組織，並提高鋼種的韌性。通常與硅結合使用以獲得半鎮靜或完全鎮靜的鋼。

14.鈦（Ti）

Ti用於控制晶粒尺寸的增長，從而提高韌性。還可以將硫化物夾雜物從長形延伸到球形，從而改善強度和耐腐蝕性以及韌性和延展性。

Ti是一種非常堅固，非常輕的金屬，可以單獨使用或與鋼製成合金。將其添加到鋼中可使其在高溫下具有較高的強度。現代噴氣發動機使用鈦鋼。

    它可以防止長時間加熱時不銹鋼中鉻的局部消耗
    防止高鉻鋼中形成奧氏體
    降低中鉻鋼的馬氏體硬度和淬透性。

15.鈮（Nb，以前稱為Columbium-Columbium，Cb）

鈮是關鍵的晶粒細化元素，也是鋼鐵生產中增強強度的元素。鈮是強硬質碳化物，形成非常硬，非常小，簡單的碳化物。提高延展性，硬度，耐磨性和耐腐蝕性。此外，細化晶粒結構。前身為Co。

16.硼（B）

鋼中硼的最重要作用和目的是大大提高淬透性。

硼的最大優點是可以添加少量硼，以獲得與增加淬透性所需的大量其他元素相同的結果。鋼合金的典型範圍是0.0005至0.003％。

在熱處理過程中，添加了硼來替代其他元素，以提高中碳鋼的淬透性。高速鋼的切削性能得到提高，但以鍛造質量為代價。硼的含量也可能過高，這會降低淬透性，韌性並引起脆化。鋼中存在的碳百分比也對硼的淬透性影響。隨著硼對淬透性的影響增加，應按比例減少碳含量。

將硼添加到鋼中時，必須採取預防措施以確保其不會與氧氣或氮氣發生反應，因為硼與二者之一的組合會使硼無用。

17.鉛（Pb）

極少量添加鉛可提高可加工性，最高可達0.30％，可改善可加工性。如果分佈均勻，則對鋼的物理性能幾乎沒有影響，並且與普遍的看法相反，它不影響焊接能力。

18.鋯（Zr）

鋯被添加到鋼中以改變夾雜物的形狀。通常添加到低合金，低碳鋼中。結果是，當形狀從拉長變形為球狀時，韌性和延展性得到改善，從而提高了韌性和延展性。

19.鉭（Ta）

因此，化學上與鈮（Nb）非常相似，對合金具有相似的作用-形成非常硬，非常小，簡單的碳化物。提高延展性，硬度，耐磨性和耐腐蝕性。此外，精煉穀物。

20.氮（N）

氮的作用與合金中的碳非常相似。 N可以少量（甚至在現代技術中甚至可以代替）C來增加硬度。顯然，氮形成氮化物，而不是碳化物。 INFI有N，還有更多，而山特維克（Sandvik）是冠軍，其合金中N的含量為3％，完全取代了C。可惜的是，這不適用於刀具製造商。由於氮比碳更容易形成碳化鉻，因此氮不易形成氮化鉻，因此氮的存在可提高耐腐蝕性，從而在合金中留下更多的游離鉻。由於氮在形成氮化物時反應性較低，因此可用於增加硬度而不會增加碳化物的尺寸和體積，例如：山特維克14C28N鋼。

21.硒

通常在餐具鋼中是不希望的。添加以提高可加工性。在相同的硫屬元素組中與硫相似。

上面顯示的所有化學元素和作用與鋼鐵材料有關。因此，如果您從事鋼鐵行業，則應保持相同。

上面沒有列出其他一些小的稀有金屬元素。您可以在下面留下評論，並提供詳細信息。