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一、概况在柴油机油嘴油泵行业中,原来制订的三对精密偶件金相标准NJP7—76中,仅有18Cr_2Ni_4W一种钢材是属于渗碳的,而且这
First, an overview Diesel engine oil pump industry, the original formulation of the three pairs of precision parts gold standard NJP7-76, only 18Cr_2Ni_4W a steel is carburized, and this