Chromoly Vs Mild Steel K Member

4130 alloy steel carbon steel vs.

Chromoly vs mild steel k member.

Crome molly chromemoly has a higher ultimate strength so it is much harder and a mild steel cage will fail before it does. But the fact is someone has had a problem with all brands steel or chromoly. Also keep in mind that it is harder to weld the 4130 than the mild steel. There are going to be people saying chromoly will crack or i have this friend that blah blah blah.

Ths tress relieving part is bogus. I am cheap so upr was the one for me they have had their problems in the past but the k members have been redesigned and are much better. Drag racers benefit more from using chromoly because they can use a thinner wall steel over mild. The chromium adds strength hardenability and a level of corrosion resistance to mild carbon steel though chromoly is not as corrosion resistant as stainless steel.

A 25 5 cage will cert a car to run 7 50 or slower at a max weight of 3600 pounds. Some are stronger then others but some you are going to pay out the ass for. In nasa we have to use the same gauge whether it is mild or chromoly so the benefit of light weight is not as great. When racecars were just beginning to be made from chrome moly there were brittle failures caused by the lack of heat treating and stress relieving.

This kit was designed for the abuse of hardcore drag race road race and street enthusiasts. 4130 alloy steel. Upr s all new chrome moly k member will save more weight and exceed any strength limitations of mild steel while allowing maximum header and oil pan clearance. Chromoloy tubing is made from a family of low alloy steels that contain chromium and molybdenum sae 4130 or 4140 along with the iron carbon and other elements.

Use er70s wire and you won t need to passivate the welds since the wire is ductile. A sfi 25 5 cage can be either mild steel or chromoly however a 25 2 cage must be chromoly only.