GB/T 26655-2022 in English

GB/T26655-2022, as the national authoritative standard for vermicular graphite cast iron parts, replaces the 2011 version to achieve three major upgrades: refinement of technical indicators (such as the creep rate increased from ≥50% to ≥80%), standardization of detection methods (new metallographic inspection specifications), and systematization of application guidance (typical application cases are added to the appendix).

Cream rate control:The standard clearly requires that the proportion of vermicular graphite in the graphite morphology should be ≥80%, and the amount of vermicular agent added should be accurately controlled by chemical analysis methods such as diantipyrine methane phosphomolybdic acid weight method.

Test block selection:Single casting test block (Figure 1), side-by-side test block (Figure 2) or attached casting test block (Figure 4) should be selected according to the difference in casting wall thickness. The cooling rate of the test block should be consistent with the actual working condition of the casting.

Abnormal spheroidization rate: When the roundness coefficient ρ＜0.525 (Appendix F), it is necessary to check the titanium content (should be ≤0.08%) and the inoculation process to prevent the formation of Ti(C,N) hard phase.

Processing performance optimization: Appendix G points out that the manganese content is controlled in the range of 0.3%-0.45%, which can balance the relationship between pearlite content and tool wear.