Author Archives: LF Engineering

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Intergranular corrosion of a martensitic stainless steel

Martensitic stainless steel (420B) microstructure show carbides precipitate at grain boundaries. Chromium, present in the matrix to guarantee corrosion resistance, is taken away to form chromium carbides. This causes a strong reduction in the corrosion resistance just near the carbides. This … Continue reading

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Failure

Cylinder block is made of one piece of spheroidal cast iron. It broke due to the impact of a failed piston rod. It is evident observing  the picture, there are no possibilities to repair the damaged cylinder block. Spheroidal cast iron can not … Continue reading

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Stress corrosion cracking of an austenitic stainless steel

Achilles’heel of austenitic stainless steel is stress corrosion cracking. This steel family, born to sove any problem in corrosion is particularly susceptible to SCC in mildly  aggressive chloride environments. In the image the typical aspect of a SCC crack. It propagates normal to the applied … Continue reading

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Ferritic stainless steel welding

Ferritic stainless steel resistance welding The welding of ferritic stainless steel presents certain problems, at times underestimated. We must not only worry about the precipitation of carbides at the grain border, the embrittlement due to a constant 475°C, or the … Continue reading

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Tool joint box

Martensitic microstructure on thread flank. Martensitic microstructure is present on the thread flank and no diffusion area on the base material are present. Microhardness indentations confirm the observation: martensite hardness is around 750 HV, instead base material is around 350 … Continue reading

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Stress corrosion cracking of cabon steel plate

Stress corrosion cracking on a carbon steel. Stress corrrosion cracking is a material failure that present a rapid crack propagation. SCC happens in a particular environment, for a particular material in presence of tension stresses. The image, taken during the tuna can steel failure … Continue reading

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