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我厂生产叉车变速箱内的花键轴(40Cr),要求表面硬度HRC44～46。原工艺采用高频加热喷水淬火,340℃回火,硬度达到图纸要求且无表面裂纹,但经磁力探伤后,发现部分零件有微裂纹,我们改用聚乙烯醇合成淬火剂进行喷液淬火,解决了这一问题。它的冷却特性是,在高温区具有较快的冷却速度,平均为288～342℃/秒,与水近似,在低温区冷速慢,平均为120～173℃/秒,近似于油,因此可以防止裂纹。一、溶液配制聚乙烯醇是一种非离子型高分子化合物,聚合度1750,醇解度88%,配比性能良好。1.配方:聚乙烯醇10%(防裂剂);三乙醇胺1%(防锈剂);苯甲酸钠0.2%(防腐剂);太古油0.02%(消泡剂);其余是水。2.配制:先把水和聚乙烯醇按上述规定配比放进铁桶里加热到90℃左右,边加热,边搅
I plant production forklift gearbox spline shaft (40Cr), the required surface hardness HRC44 ~ 46. The original process using high-frequency heating spray quenching, tempering at 340 ℃, the hardness of the drawings to meet the requirements and no surface cracks, but after magnetic testing, found that some parts of micro-cracks, we use polyvinyl alcohol quenching agent for quenching , To solve this problem. Its cooling characteristics are that it has a faster cooling rate in the high temperature range, with an average of 288 to 342 ° C / s, which is similar to that of water and has a slow cooling rate in the low temperature range of 120 to 173 ° C / sec on average, which approximates to oil. Can prevent cracks. First, the solution preparation Polyvinyl alcohol is a non-ionic polymer compounds, degree of polymerization 1750, alcoholysis degree of 88%, the ratio of good performance. 1. Formula: Polyvinyl alcohol 10% (anti-cracking agent); triethanolamine 1% (rust inhibitor); sodium benzoate 0.2% (preservative); Swire Oil 0.02% (defoamer); the rest is water. 2. Preparation: first water and polyvinyl alcohol according to the provisions of the ratio into the iron drum heated to about 90 ℃, while heating, while stirring