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白点是钢的内部缺陷,又叫发裂。是钢中氢含量偏高和内应力共同作用的结果。奥氏体、铁素体和莱氏体钢一般不形成白点,而马氏体、贝氏体和珠光体钢易形成白点。16MnR属于低碳钢,一般说来其氢致裂纹敏感性较低,不易产生白点,但83年我们在50mm厚16MnR钢板拉力试样上连续发现两炉钢产生白点缺陷。本文介绍16MnR钢白点宏观、微观形貌、白点形成原因,并对白点断口微观机制进行探讨。一、白点的宏观、微观形貌 1。酸浸低倍特征钢板纵向的中央区有断断续续的小裂口,并具有一定的深度。由于多道轧制的原因,这些小裂口几乎和轧向平行。用放大镜可观察到小裂口两端稍尖、略呈锯齿状。 2。宏观断口及拉力试样上的白点特征在横向φ20mm拉力试样表面有“人”
White point is the internal defects of steel, also known as cracking. It is the result of the high hydrogen content in steel combined with the internal stress. Austenitic, ferritic and ledeburitic steels generally do not form white spots, while martensite, bainite and pearlite steels tend to form white spots. 16MnR is mild steel, generally speaking, its hydrogen induced cracking sensitivity is low, not easy to produce white spots, but in 83 we found the white spot defects of two furnaces successively on the tensile specimens of 50mm thick 16MnR steel. In this paper, the macro, micro-morphology and white-spot formation of 16MnR steel are introduced, and the microscopic mechanism of white point fracture is discussed. First, the white macro, micro-morphology 1. Acid leaching characteristics of the lower longitudinal center of the plate has intermittent small cracks, and has a certain depth. Due to the multi-pass rolling, these small cracks are almost parallel to the rolling direction. With a magnifying glass can be observed at both ends of a small sharp tip, slightly jagged. 2. Macroscopic fracture and tensile specimen characteristics of the white point in the horizontal ф20mm tensile specimen surface “person”