硫化物产生于在给不锈钢零件添加硫以改善其可加工性的过程中。硫化物改善了合金形成切屑的能力，在加工过程中，这种切屑可以很干脆地从刀具上脱离。除非零件经过适当钝化，否则硫化物有可能会充当在加工后的产品表面上发生腐蚀的最初场所。
Sulfides are generated during the process of adding sulfur to stainless steel parts to improve their machinability. Sulfides improve the ability of alloys to form chips, which can easily detach from the tool during processing. Unless the parts are properly passivated, sulfides may serve as the initial site for corrosion on the surface of the processed product.
不锈钢零件
Stainless steel parts
在这两种情况下，都需要采用钝化过程来进步不锈钢的自然防腐性能。不锈钢零件可以往掉表面污染，诸如有可能形成锈蚀或充当发生腐蚀最初场所的、含铁的车间灰尘以及来自刀具的铁微粒等。钝化还可以往掉暴露在可自由加工不锈钢合金表面中的硫化物。
In both cases, passivation processes are needed to improve the natural corrosion resistance of stainless steel. Stainless steel parts can cause surface contamination, such as the possibility of forming rust or serving as the initial site of corrosion, iron containing workshop dust, and iron particles from cutting tools. Passivation can also remove sulfides exposed on the surface of freely machinable stainless steel alloys.
采用一种由两步组成的工艺，可以保证最好的防腐性能：1. 清洗，这是最基本的一步，但有时候却被忽略；2.酸浴或钝化处理。
Adopting a two-step process can ensure the best anti-corrosion performance: 1 Cleaning is the most basic step, but sometimes it is overlooked; 2. Acid bath or passivation treatment.
钝化可自由加工不锈钢的过程与钝化难加工不锈钢的过程有所不同。这是由于，含硫的、可自由加工不锈钢中的硫化物，在钝化过程中会在典型的硝酸浴中部分或彻底往掉，从而在加工好的零件表面形成微观非连续性。
The process of passivating freely machined stainless steel is different from that of passivating difficult to machine stainless steel. This is because sulfides in sulfur-containing and freely machinable stainless steel will partially or completely fall off during the passivation process in a typical nitric acid bath, forming microscopic discontinuities on the surface of the processed parts.