五个影响彩涂板钢基的化学元素
氧的作用
氧在钢中的溶解度很小,氧化物以夹杂物的形式存在于钢中。一般来说,氧含量增加,夹杂物增多,钢板韧性降低,疲劳强度、耐磨性等力学性能也有不同程度的降低。在炼钢过程中,氧气被用来除去钢液中的杂质元素,因此氧气起到了积极的作用。但它对实心钢有害。因此,脱氧是必要的。
氮的影响
钢中的氮来自炉料。在冶炼过程中,钢水也从炉气中吸收氮气。氮引起碳钢的淬火时效和变形时效,对碳钢的性能有着重要的影响。时效使钢的硬度和强度提高,但韧性降低。特别是在变形时效的情况下,韧性的降低比较显著。对于普通低合金钢来说,时效现象是有害的,氮是有害元素。
在钢中加入足够的铝可以形成氮化铝,消除或减弱时效现象。氮化铝具有高度的分散性和稳定的织构,可以细化晶粒。在这方面,氮是一种有益的元素。
氢的作用
在表面熔制过程中,钢水不仅能从生锈和水化的炉料中带氢,而且能直接从炉气中吸收氢。当钢在含有氢的还原性保护气体中加热时,它可以在酸洗、电镀或电解过程中吸收氢。氢以离子或原子的形式溶解成液态或固态钢,然后熔化成固态钢,形成间歇固态熔体。氢是钢中的有害元素,会降低钢的韧性,导致所谓的氢脆。另一方面,钢的强度越高,氢脆敏感性越大。
铝的影响
钢中加入铝作为脱氧元素,钢液中的铝部分与氧结合形成氧化铝或各种含有氧化铝的夹杂物。除铝的脱氧作用外,铝氮结合形成的弥散AlN颗粒还可以阻止奥氏体晶粒长大。因此,钢中必须保证一定量的酸溶铝。
其他残余元素的影响
废钢或矿石带入碳钢中的元素有铜、镍、铬等,为防止各类碳钢性能波动幅度过大,其含量受到一定的限制。但这些元素的存在将在一定程度上提高热轧的强度
The effect of oxygen
The solubility of oxygen in steel is very small, and the oxide in steel appears in the form of inclusions. Generally speaking, the oxygen content is increased, the inclusions are more, the toughness of steel plate is reduced, and other mechanical properties
such as fatigue strength and wear resistance are also reduced in varying degrees. In steel making, oxygen is used to remove the impurity elements in the steel liquid, so oxygen has played a positive role. But it is harmful to solid steel. Therefore, deoxidization
is necessary.
Effect of nitrogen
The nitrogen in the steel comes from the furnace charge. During smelting, the molten steel also absorbs nitrogen from the furnace gas. Nitrogen causes quenching aging and Deformation Aging of carbon steel,
which has a significant impact on the performance of carbon steel. As a result of aging, the hardness and strength of steel are increased, but the toughness should be reduced. Especially in the case of Deformation Aging, the reduction of toughness is
relatively significant. For ordinary low alloy steel, aging phenomenon is harmful, so nitrogen is a harmful element.
Adding enough aluminum to steel can form aluminum nitride, which can eliminate or weaken aging phenomenon. Because aluminum nitride
is highly dispersed and has stable texture, it can refine grains. In this respect, nitrogen is a beneficial element.
The effect of hydrogen
In the smlting process, the molten steel can not only bring hydrogen from the rusty and watery charge,
but also directly absorb hydrogen from the furnace gas. When the steel is heated in the reducing protective gas containing hydrogen, it can absorb hydrogen in the pickling process, electroplating or electrolysis process. Hydrogen dissolves into liquid
or solid steel in the form of ions or atoms, and then melts into solid steel to form intermittent solid melt. Hydrogen is a harmful element in steel, which reduces the toughness of steel and causes so-called hydrogen embrittlement. On the other hand,
the higher the strength of steel, the greater the sensitivity of hydrogen embrittlement.
The influence of aluminum
Aluminum is added to steel as a deoxidizing element, and the aluminum part in the molten steel combines with oxygen to form
Al2O3 or various inclusions containing Al2O3. In addition to the deoxidizing effect of aluminum, the dispersed AlN particles formed by the combination of aluminum and nitrogen can prevent austenite grain growth. Therefore, a certain amount of acid soluble
aluminum must be ensured in the steel.
Influence of other residual elements
There are als some elements brought into carbon steel by scrap steel or ore, such as copper, nickel, chromium, etc. in order to keep the performance fluctuation range
of all kinds of carbon steel from too large, their contents are limited to a certain extent. But the existence of these elements will improve the strength of hot rolling to a certain extent.