草久久精品,成人久久亚洲,日本一道本在线视频,国产精品99一区二区,一区二区三区综合,久久精品5,自拍偷拍你懂的

Casus Products>> Casus

  51B20 has stable chemical composition, low harmful elements, the purity of steel is high, the advantages of small decarburized layer, good surface quality. After spheroidize annealing, the cold heading property is excellent. The product has good hardenability. Mainly used in the production of 10.9 high strength bolts, suitable for construction, machinery and other fields, widely used in exports.