6 产品缺陷及消除办法热推弯头常见的产品缺陷和消除办法分述如下。 6.1延伸率不合在对弯头进行机械性能检验时,经常出现延伸率不合。其产生原因是:生产弯头的钢管延伸率虽符合我国钢管标准的规定,但往往比美国的钢管标准低得多(美国弯头标准规定的延伸率与钢管标准相同),经热推后弯头的延伸率仍达不到美国标准要求。当热推弯头的温度低于Ac_3时,虽然钢管的延伸率达到美国标准要求,但弯头的延伸率仍略低于美国标准规定值。 6 product defects and elimination of hot elbow bend common product defects and elimination methods are described below. 6.1 Elongation in elongation Elbow in the mechanical properties of the test, often with different elongation. The reason is that although the elongation of steel pipe in production elbow is in line with China’s steel pipe standard, it is often much lower than that of the United States steel pipe (American Elbow standard provides the same elongation as the steel pipe standard) Head extension is still less than the United States standards. When the temperature of the hot elbow is lower than Ac_3, although the elongation of the steel pipe meets the requirements of U.S. standards, the elbow elongation is still slightly below the U.S. standard.