Discoloration during welding of stainless steel 

Hello. Thank you, very good video. Would love to see a video in more detail.

Hello, Dr. Köcher. Many thanks to explain as well this topic. I was investigating something around and I would like to contribute by mention that Acceptance Criteria is indicated in ASME BPE for product and non product contact surfaces. ISO 5817 also mention limits for imperfections for quality levels. An extract of "The Official Magazine of ISPE" by Ken Kimbrel, shows a tables where you can see weldings done by different oxigen level and its correspondance with piting corrosion resistance decrease, but also mention what level of resistance you could restore by post weld treatment like electrochemical cleaning and passivating. For the last, the Force Institute also provides a Chart with similar Heat Tint Levels and its correspondance with oxigen used in Argon or Formied gas. Saludos desde, México.

Thank you ❤️

Hi, Dr. Köcher. Yesterday i was discussing about the harmful level of HAZ depending on color. I have used your graphic showed in the video in order to define acceptable ranges for CPP. What I want to know is: when starts to lose the passive layer? As I understand Light raw yellow and pale yellow are not harmful zone, but what happened when the CPP decrease due to a brown color, is the passive layer missing? And what about the blue colors, in comparison with yellow seems like no problem occur. To explain better: SS 304L has a CPP about 500 mV, and after welding if HAZ appear the CPP could decrease to 270 mV and lose the passive layer, so for this value what would be the tint (yellow, brown or blue)? Could you be so kind to share with me the document that contain the graphic and their explanation? Saludos