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IMO...
just looking at the welds and the effective tear area and the reported material of construction (pipe), I would guess the cause is torsional stress.
What is mild steel? Usually designsted as SAE 1010 or Mild steel contains approximately 0.05–0.30% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing.
Various Mild steel grades based on Tensile Strength as per latest Indian Standards IS 1069 Rev 6 are ; HRO: Ordinary Grade : TS not specified. HR1 : Commercial Gr : TS 440 MPa Max. HR2
rawing Gr : TS 420MPa Max.
Mild steel has a high resistance to breakage. Mild steel, as opposed to higher carbon steels, is quite malleable, even when cold. This means it has high tensile and impact strength. Higher carbon steels usually shatter or crack under stress, while mild steel bends or deforms.
Basically, the use of "mild" steel is a low carbon steel, easily formed and low cost material. Most, but not all, mild steel pipe is roll formed and continuously welded from flat stock to a specific length, typically 21' lengths. Because of the roll forming, stresses can develop along the weld seam. These stresses can be aggravated by an external force's such as forming the pipe into exhaust system components and adfitional welding (attaching the xover connection). The fix??? Usually, annealing or normalizing the pipe after fabrication relieves these stresses. Or using a higher grade of steel or stainless steel (higher carbon content) will also help but will make for a significantly higher price.
Recommend either talking with the original manufacturer or V out the cracks and TIG weld the area using a higher grade of filler metal and perhaps post weld heat treating the repaired areas to relieve any stress.
Just my opinion of course.
BOB RENTON
just looking at the welds and the effective tear area and the reported material of construction (pipe), I would guess the cause is torsional stress.
What is mild steel? Usually designsted as SAE 1010 or Mild steel contains approximately 0.05–0.30% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing.
Various Mild steel grades based on Tensile Strength as per latest Indian Standards IS 1069 Rev 6 are ; HRO: Ordinary Grade : TS not specified. HR1 : Commercial Gr : TS 440 MPa Max. HR2
rawing Gr : TS 420MPa Max.Mild steel has a high resistance to breakage. Mild steel, as opposed to higher carbon steels, is quite malleable, even when cold. This means it has high tensile and impact strength. Higher carbon steels usually shatter or crack under stress, while mild steel bends or deforms.
Basically, the use of "mild" steel is a low carbon steel, easily formed and low cost material. Most, but not all, mild steel pipe is roll formed and continuously welded from flat stock to a specific length, typically 21' lengths. Because of the roll forming, stresses can develop along the weld seam. These stresses can be aggravated by an external force's such as forming the pipe into exhaust system components and adfitional welding (attaching the xover connection). The fix??? Usually, annealing or normalizing the pipe after fabrication relieves these stresses. Or using a higher grade of steel or stainless steel (higher carbon content) will also help but will make for a significantly higher price.
Recommend either talking with the original manufacturer or V out the cracks and TIG weld the area using a higher grade of filler metal and perhaps post weld heat treating the repaired areas to relieve any stress.
Just my opinion of course.
BOB RENTON
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