Hi Natan,

low P and more in general low X (Bruscato) factor are desirable for high temperature applications to preserve strenght and creep resistance of Cr and CrMo Steels. Around 100-150 ppm is the maximum allowed especially on welded joints to reduce high temperature viscous flow and failures. CrMo Steels up to P91 and P92 types are used in power generation, oil&gas industry and for pipelines realizations.

No major influence on C steel or HSLA.

best regards,

Simone

P widens the austenite-liquid 2 phase (pasty) zone of Fe-C diagram, and Fe-C-P ternary has lower melting point than Fe-C binary. Due to widened 2-phase region, more extensive segregation occurs, which is unfortunately can not be homogenized easily due to extremely sluggish Diffusion of P in Fe. As a result, the cooled product remains inhomogenous and become susceptible to stress concentration and cracking, This king of cracking during cold/ warm rolling results in classic "cold shortness"

The industries requiring repeated rolling to made products, and specifically those who are expecting the product to be subjected to repeated loading, significantly emphasize on low or Ultra-low P steel. One such example is Automobiles industry, (sheet metal body to be specific).

Interestingly, virtually C free iron, in presence of P, is ductile enough to be deep drawn into piano wires! It can impart somewhat corrosion resistance to low C steels as well, as the case of Famous Iron pillar of Delhi.

you can check out this link

https://www.totalmateria.com/page.aspx?ID=CheckArticle&site=kts&NM=211