白点

  　  白点是锻件在锻后冷却历程中产生的一种里面缺点。其形貌在横向低倍试片上为细发丝状锐角裂纹，断口为银白色雀斑。照片6-13为Cr－Ni－Mo钢锻件纵向断口上的白点。其形状不准则，大小悬殊，非常小长轴尺寸仅2mm，非常大的为24mm。白点本色是一种脆性锐边裂纹，具备极大的风险性，是马氏体和珠光体钢中非常凶险的缺点。

    白点成因是钢中氢在应力用途下向拉应力区富集，使钢产生所谓氢脆，发生脆性断裂，以是氢和附加应力团结用途是白点产生的缘故。

　   对策是：

　    1）低落钢中氢含量，如留意烘烤炉料，冶炼时充分沸腾，真空除气，炉外精炼脱气等。

  　  2）接纳消除白点的热处理，要紧使命是分散钢中氢，消除应力，如扩氢退火热处理等。详见铸造历程中多见的缺点中的锻后清算工艺欠妥常产生的缺点。

自由锻件直销哪家好，就找唐山盛通锻造有限公司。

White dot

   The white point is one of the shortcomings that the forging produced during the post-forging cooling process. Its shape is a fine hairline acute angle crack on the lateral low-magnification test piece, and the fracture is silvery white freckles. Photo 6-13 is the white point on the longitudinal fracture of the Cr-Ni-Mo steel forging. Its shape is not standard, the size is very different, very small long axis size is only 2mm, very large is 24mm. The white point is a brittle sharp edge crack with great risk and is a very dangerous shortcoming in martensite and pearlitic steel.

     The cause of white spots is that hydrogen in steel is concentrated in the tensile stress region under stress, which causes so-called hydrogen embrittlement and brittle fracture, so that the joint use of hydrogen and additional stress is caused by white spots.

The countermeasures are:

1) The hydrogen content in the low steel, such as paying attention to the baking charge, fully boiling during smelting, vacuum degassing, refining outside the furnace and so on.

   2) Accepting the heat treatment to eliminate white spots, the important task is to disperse hydrogen in the steel and eliminate stress, such as hydrogen expansion annealing heat treatment. See the shortcomings of the post-forging clearing process in the most common shortcomings in the casting process.