Both 20# seamless steel pipe and 20G seamless steel pipe are carbon structural steel with average carbon content of 0.20%. There are big differences in the use standard, chemical composition, mechanical properties and price between S690QL steel plate manufacturers, 20# seamless steel pipe and 20G seamless steel pipe, so they must be selected correctly in the design and use, so as to avoid affecting the service life or even causing destructive accidents. The purpose of S690QL steel plate manufacturers, GB8162 20# seamless steel pipe is for general structure, the purpose of GB8163 20# seamless steel pipe is for conveying fluid, and the purpose of GB3087 standard 20# seamless steel pipe is for low and medium pressure boiler. 20G seamless steel pipe is used for high pressure steam boiler and pipeline.
The strengthening mechanisms in metals mainly include solid solution strengthening, dislocation strengthening, fine grain strengthening, and second phase (precipitation and dispersion) strengthening. Alloying elements have the most significant strengthening effect on steel in the quenched and tempered state, because it makes full use of all four strengthening mechanisms. Martensite is formed during quenching, and carbides are precipitated during tempering, resulting in a strong second phase strengthening and greatly improving toughness. Therefore, obtaining martensite and tempering it is the most economical and effective comprehensive strengthening method for S690QL steel plate manufacturers.
Steel S690QL steel plate manufacturers exports fell sharply year on year. According to the data of the General Administration of customs, 7.811 million tons of steel were exported from January to February, a year-on-year decrease of 27.0%; 2.041 million tons of imported steel, a year-on-year increase of 2.1%. Steel prices continue to fall. According to the monitoring of China Iron and Steel Industry Association, China's steel S690QL steel plate manufacturers composite price index at the end of January was 105.48 points, down 0.58% month on month; at the end of February, the index continued to decline to 100.39 points, down 4.83% month on month.