Bainitic Transformation

A diffusion-controlled transformation process of austenite at intermediate temperatures, resulting in a fine acicular mixture of ferrite and carbides. This provides high toughness combined with good strength.

Bainite forms when you cool the steel after welding in a medium temperature range – sort of between ferrite and martensite. You get a fine structure of ferrite and carbides that is tough and stable. But watch the cooling rate: if you cool too fast, you get martensite, which is hard and can crack. If you cool too slowly, the structure becomes coarse and toughness suffers. The right cooling time in the critical range is key to ensure the transformation goes cleanly and you don't get nasty surprises in the weld.

MetallurgieSchweißtechnik