1、 The harm of nitrogen

氮不能一概而论的归结为有害气体元素，因为有些特种不锈钢是有目的的加入氮。所有的不锈钢均含有氮，其存在量取决于不锈钢的生产方法，合金元素的种类、数量及其加入方式，不锈钢的浇铸方法，以及是否有目的的加入氮。有些牌号的不锈不锈钢，适当增加N的含量，可以减少Cr的使用量，Cr相对很贵，此方法可以有效降低成本。

Nitrogen can not be generalized as harmful gas elements, because some special stainless steel is purposefully added nitrogen. All stainless steels contain nitrogen, and its amount depends on the production method of stainless steel, the type, quantity and addition method of alloy elements, the casting method of stainless steel, and whether nitrogen is added purposefully. Some brands of stainless steel, properly increasing the content of N, can reduce the use of Cr, Cr is relatively expensive, this method can effectively reduce the cost.

不锈不锈钢中的氮大部分是呈金属氮化物的形态。例如：在存放一些时间后，不锈钢发生应变时效，就不能被深冲加工（比如深冲加工为汽车保护板），因为不锈钢会出现撕裂，不能沿各个方向被均匀地拉伸。这是由于晶粒大以及Fe4N沉积在晶粒界面上造成的。

Most of nitrogen in stainless steel is in the form of metal nitride. For example: after storage for some time, if the stainless steel has strain aging, it can not be processed by deep drawing (for example, deep drawing is processed as automobile protection plate), because the stainless steel will tear and cannot be evenly stretched in all directions. This is due to the large grain size and the deposition of Fe4N on the grain interface.

二、氢的危害

2、 Harm of hydrogen

当不锈钢中氢含量大于2ppm时，氢在所谓“鳞片剥落”现象中起重要作用。在滚轧和锻造后的冷却过程中出现内裂和断裂现象时，这种剥落现象一般更加明显，而且在大的断面或者高碳不锈钢中更经常发现这种现象。

When the hydrogen content in stainless steel is more than 2ppm, hydrogen plays an important role in the so-called "flake off" phenomenon. The spalling phenomenon is more obvious in the cooling process after rolling and forging, especially in large section or high carbon stainless steel.

由于内应力的存在，这种缺陷会造成发动机使用过程中大转子发生崩裂。铸铁中氢大于2ppm时，容易出现孔隙或一般的多孔性，这种氢造成的多孔性将造成铁的脆化。“氢脆”主要出现在马氏体不锈钢中，在铁氧体不锈钢中不十分突出，而在奥氏体不锈钢中实际上尚不清楚。另外，氢脆一般与硬度和含碳量一起增加。

Due to the existence of internal stress, this kind of defect will cause the large rotor to crack in the process of engine use. When the hydrogen content in cast iron is more than 2ppm, it is easy to have pores or general porosity, which will cause embrittlement of iron. Hydrogen embrittlement mainly occurs in martensitic stainless steel, which is not prominent in ferrite stainless steel, but is not clear in austenitic stainless steel. In addition, hydrogen embrittlement generally increases with hardness and carbon content.

三、氧的危害

3、 The harm of oxygen

氧和氢一样，都会对不锈钢的机械性能产生不良影响。不仅是氧的浓度，而且含氧的夹杂物的多少、类型及其分布等也有很重要的影响。这类夹杂物是指金属氧化物、硅酸盐、铝酸盐、含氧硫化物以及类似的夹杂化合物。炼不锈钢需要脱氧，因为凝固期间，溶液中氧和碳反应会生成一氧化碳，可以造成气泡。

The mechanical properties of stainless steel are the same as those of hydrogen and oxygen. It is not only the concentration of oxygen, but also the number, type and distribution of inclusions containing oxygen. This kind of inclusion refers to metal oxide, silicate, aluminate, oxysulfide and similar inclusion compounds. Deoxidation is necessary for stainless steel production, because during solidification, carbon monoxide will be generated from the reaction of oxygen and carbon in the solution, which can cause bubbles.

另外，冷却时氧可以作为FeO、MnO以及其他氧化夹杂物从溶液中析出，从而削弱其热加工或冷加工性，以及延展性、韧性、疲劳强度和不锈钢的械加工性能。氧与氮和碳还能引起老化或者硬度在室温下自发的增加。对于铸铁，当铸块正凝固时，氧化物与碳可以发生反应，因此造成产品的孔隙和产品的脆化。

In addition, oxygen can be precipitated from the solution as FeO, MnO and other oxide inclusions during cooling, which weakens the hot or cold workability, ductility, toughness, fatigue strength and machinability of stainless steel. Oxygen, nitrogen and carbon can also cause aging or spontaneous increase in hardness at room temperature. For cast iron, when the ingot is solidifying, the oxide can react with carbon, resulting in porosity and embrittlement of the product.