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等温淬火能显著改善灰口铸铁的力学性能,而通过渗硼等化学热处理提高其表面硬度能进一步扩展它的应用范围。本文研究用灰口铸铁试样的成分为3.6%C-2.1%Si-0.43%Mn-0.26%Cr-bal Fe。等温淬火工艺采用900℃奥氏体化,随后在240℃、300℃和360℃的盐浴中分别保持1 h、2 h、3 h和4 h后空冷。对另一组试样进行渗硼等温淬火处理,其工艺为在950℃熔融硼砂中渗硼2~4 h,随后在240℃、300℃和360℃盐浴中分别保持1 h、2h、3 h和4 h后空冷。这种工艺不需为了等温淬火而另外加热。通过试样显微硬度的测定和黏着磨损性能试验发现,等温淬火显著提高了灰口铸铁的性能,而渗硼等温淬火则更进一步改善了灰口铸铁的性能。
Isothermal quenching can significantly improve the mechanical properties of gray cast iron, and by boronizing chemical heat treatment to increase its surface hardness can further expand its scope of application. In this paper, the composition of gray cast iron samples is 3.6% C-2.1% Si-0.43% Mn-0.26% Cr-bal Fe. The austempering process was austenitized at 900 ° C followed by air cooling in salt baths at 240 ° C, 300 ° C and 360 ° C for 1 h, 2 h, 3 h, and 4 h, respectively. Boronizing isothermal quenching was performed on another group of samples by boronizing for 2 to 4 h at 950 ° C in molten borax followed by 1 h, 2 h, 3 h in salt baths at 240 ° C, 300 ° C and 360 ° C, respectively h and 4 h after air cooling. This process does not require isothermal quenching and additional heating. Through the determination of the microhardness of the sample and the adhesive wear performance test, it was found that the isothermal quenching significantly improves the properties of the gray cast iron, while the boronizing isothermal quenching further improves the performance of the gray cast iron.