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一、前言钢淬火时,只要钢材的尺寸小到心部也受到大干此钢的临界冷却速度冷却时,那么直到心部都会完全硬化。但当钢的尺寸大到某个尺寸以上时,就只能表面被淬硬而心部却不能被淬硬。这时淬硬的表面呈现马氏体组织,渐次深入其内部时屈氏体增多,硬度亦逐渐下降,这是一般的现象。下面我们把这种现象称为正常硬化现象。然而轴承钢油淬时经常看到与此完全相反的现象,即往往在表面上产生屈氏体或贝氏体,向内逐渐减少,而马氏体由表向里反而逐渐增多,硬度也是表面低逐渐向内变高,这种现象称为逆硬化现象。与这种逆硬化颇为相似的现象,即表面硬
First, the foreword quenching steel, as long as the size of the steel is also affected by the heart of the steel cooling critical cooling rate, then until the heart will be completely hardened. However, when the size of steel is larger than a certain size, the surface can only be hardened and the heart can not be hardened. At this moment, the hardened surface presents martensite structure, gradually increasing its internal volume of troostite and gradually decreasing the hardness, which is a general phenomenon. Here we call this phenomenon normal hardening phenomenon. However, the oil quenching bearing steel often see the opposite phenomenon with this, that is often produced in the surface troostite or bainite, inward gradually decreased, while the martensite gradually increased from the table to the contrary, the hardness is also the surface Low gradually becomes higher inward, this phenomenon is called inverse hardening phenomenon. Quite similar to this phenomenon with the reverse hardening, that is hard surface