碳钢在卷曲，归一化或硬化和恢复状态中提供，其最佳特性是由硬化和调速而产生的。碳含量对拉伸强度，对失败的伸长和退火普通碳钢的硬度的影响如图1所示。
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Figure 1.The effect of carbon content and heat treatment on the typical properties of plain carbon steels. |
Very Low Carbon Content SteelsVery low carbon content (up to 0.05%C). These steels are ductile and have properties similar to iron itself. They cannot be modified by heat treatment. They are cheap, but engineering applications are restricted to non-critical components and general panelling and fabrication work. 低碳含量钢Low carbon content (0.05% to 0.2%C) e.g. 080M15, 150M19, 220M07, AISI 1006, AISI 1009, AISI 1020. These steels cannot be effectively heat treated, consequently there are usually no problems associated with heat affected zones in welding. Batches which are free of 'tramp' elements such as chromium are ductile with good forming properties, as little work hardening is exhibited. However, chromium as low as 0.1% and vanadium and molybdenum contents as low as 0.05% can have a dramatic effect on hardenability. 可以通过渗碳增强表面特性，然后加热富含碳表面。高延展性会导致可加工性差，尽管如果使用高主轴速度，则可以加工这些钢。更常见的是硫和铅形成自由加工夹杂物。与清洁且没有氧化物和炉渣夹杂物的优质钢相比，具有大量硫和磷的低质量钢将具有更好的可加工性。 This group represents the bulk of the market for general purpose steel, finding usage in car bodies, ships and domestic appliances. Stainless steels and aluminium alloys compete with these steels in certain areas. Medium Carbon Content Steels中碳含量（0.2％至0.5％C），例如070M20，080M40，216M44，AISI 1023，AISI 1030，AISI 1046.热处理和工作硬化现在是修改机械性能的有效方法。坚固性与碳含量成比例增加。现在，焊工必须注意热影响区域中的硬化效应，并采取预防措施，以防止过度的能量输入，因为可耐用性增加导致形成脆性结构的可能性增加。所有共同的合金元素都提高了可耐用性，因此已设计为“碳等效”量表，以作为可焊性的近似指南（图2）。
碳等价（CE％）= C％ +（Mn％/6） +（（Cr％ + MO％ + V％）/5） +（（Ni％ + Cu％）/15）
For |
CE％<0.14 |
出色的可焊性，无需特殊预防措施 |
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0。14 |
Martensite is more likely to form, and modest preheats with low hydrogen electrodes become necessary |
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CE%>0.45 |
Extreme complications, weld cracking is very likely, hence preheat in the range 100-400°C and low hydrogen electrodes are required |
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Figure 2。计算合金钢的碳当量的方法。 |
在归一化的条件下，由于延展性较低，与低碳钢相比，可加工性可提高，如果需要特殊的“自由加工”特性，则可以通过添加硫或铅进一步增强可加工性。但是，延展性和抗冲击力降低。 这些钢的耐腐蚀性类似于低碳钢，尽管铜的少量添加在风化性能很重要时会显着改善。该类别中的大多数钢丝都包含一些硅和锰，它们在制造过程中被添加为脱氧和脱硫元素。虽然存在的数量不被视为实现机械性能，但钢和硫含量的质量表明钢的质量质量越低，含量越低，质量就越高。 This category represents medium strength steels which are still cheap and command mass market. They are general purpose but can be specified for use in stressed applications such as gears, pylons and pipelines. Medium-High Carbon Content Steels中高碳含量（0.5％至0.8％c），例如070M55，0S0M50，AISI 1055，AISI1070。这些钢非常容易受到热处理和工作硬化的影响。它们很容易变硬，并且可以治疗并锻炼以产生高抗拉力强度，前提是可以耐受耐延展性。例如，此类别中的弹簧线可以具有最终的拉伸强度（UTS）> 2GPA。显然，焊工必须小心以防止受热区（HAZ）与这些钢进行破裂，并且应始终获得专业建议。碳当量可用于评估潜在的焊接问题。 Although high strengths and hardnesses are attainable, impact strengths are poor. These steels are not normally used in stressed applications subjected to shock. They are used where hardness is valued, such as for blades, springs, collars, etc. High Carbon Content SteelsHigh carbon content (>0.8%C) e.g. 050A86, 080A86, AISI 1086, BS 1407. Cold working is not possible with any of these steels, as they fracture at very low elongation. They are highly sensitive to thermal treatments. Machinability is good, although their hardness requires machining in the normalised condition. Welding is not recommended and these steels must not be subjected to impact loading. These steels can have UTSs greater than 1 GPa, and care needs to be taken to avoid hydrogen embrittlement following electroplating. Advice should be sought from the plating shop. As with the medium-high plain carbon steels, steel with >0.8%C is used for components requiring high hardness such as cutting tools, blades, etc. |