How to Judge the Quenching Crack of ERW Casing

Quenching crack of erw casing
Quenching cracks are often produced shortly after the martensitic transformation begins, and the distribution of cracks is not necessarily regular, but it is generally easy to form at the sharp corners of the workpiece.Under the microscope observed quenching cracking, may be along the crystal cracking, it may be transgranular cracking; some radial, and some were a separate line or mesh. Due to the rapid cooling of the martensitic transformation zone caused by quenching cracks, often through the crystal distribution, and the crack is straight, there is no small cracks around the branch. Quenching cracks due to the high temperature of quenching and heating are all along the crystal distribution, the tip of the crack is tapering, and the superheat is shown: the coarse needle-like martensite can be observed in the structural steel; eutectic can be observed in the tool steel Or angular carbide. Surface decarburization of high carbon steel workpiece, quenched easily formed after the network crack. This is because the oil tank surface decarburization layer in the quenching and cooling volume expansion than the decarburization of the heart is small, the surface material by the role of expansion of the heart was cracked was reticular.

Non-quenching crack of erw casing:
In the process of quenching, the great stress produced by quenching is greater than the strength of the material itself and exceeds the plastic deformation limit. The oil pipe quenching crack is often produced shortly after the martensitic transformation begins, and the distribution of the crack is not necessarily regular, but it is generally easy to form at the sharp corners of the workpiece. Under the microscope observed quenching cracking, may be along the crystal cracking, it may be transgranular cracking; some radial, and some were a separate line or mesh. Due to the rapid cooling of the martensitic transformation zone caused by quenching cracks, often through the crystal distribution, and the crack is straight, there is no small cracks around the branch. Quenching cracks due to the high temperature of quenching and heating are all along the crystal distribution, the tip of the crack is tapering, and the superheat is shown: the coarse needle-like martensite can be observed in the oil pipeline; eutectic can be observed in the oil pipeline Or angular carbide. Surface decarburization of high carbon steel workpiece, quenched easily formed after the network crack. This is because the surface decarburization layer in the quenching and cooling of the volume expansion than the decarburization of the heart is small, the surface material by the role of expansion of the heart was cracked was reticular.