EN steel grade S420ML material country of origin

Hydrogen (H) is the most harmful element in general steel such as EN steel grade S420ML material. Hydrogen dissolved in steel will cause hydrogen embrittlement, white spots and other defects. Hydrogen, like oxygen and nitrogen, has very little solubility in solid steel. It dissolves into liquid steel at high temperature, and accumulates in the structure without time to escape when cooling, forming high-pressure micro pores, which greatly reduce the plasticity, toughness and fatigue strength of steel, and even cause cracks and brittle fracture in severe cases. "Hydrogen embrittlement" mainly occurs in martensitic steel, but not very prominent in ferrite steel, and generally increases with hardness and carbon content.

Low-alloy high-strength steel grades are designed to have quite good notch toughness for their intended structural use. The applicability of the notch toughness of specific grades of low-alloy high-strength steel is either based on existing use experience or combined with the results of the impact test of notched specimens. In order to meet the very strict requirements of certain applications, some EN steel grade S420ML material, low-alloy high-strength steels produced have excellent notch toughness. For example, controlled hot rolling technology is usually used to produce low-alloy high-strength steel plates for the manufacture of welded line pipes. Such steel pipes need to meet the requirements of relevant standards for notch toughness.

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The outer diameter of the hot-rolled seamless pipe is generally larger than 32mm, and the wall thickness is 2.5-75mm. The diameter of the cold-rolled seamless pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled pipe can be 5mm, and the wall thickness is less than 0.25mm. The size accuracy of the cold-rolled seamless pipe is higher than that of the hot-rolled seamless pipe, EN steel grade S420ML material.