ISO/TR 21704:2017包含关于圆钢链环韧性的调查和调查结果，使用小尺寸试样进行测试。 本标准适用于TH和VH级手动链式起重机的圆钢链环链，以及用于8级链式吊索的吊索链。 注1:相关国际标准为ISO 16877、ISO 16872和ISO 3076。未来，它将在新标准中实施本文件中得出的韧性结果。 对四家制造商提供的11种钢材进行了试验，以确定小尺寸试样的试验制度，以及试验产生的设计温度下缺口冲击韧性值的要求。这些要求根据全尺寸ISO-V试样的韧性值进行调整。 注2:除圆形外，这些要求也适用于链条的其他横截面。

ISO/TR 21704:2017 contains investigations and investigation results on toughness of round steel link chains, tested with sub-size specimens. It applies to round steel link chains for hand operated chain hoists of grade TH and VH and for sling chains used for chain slings of grade 8. NOTE 1 Associated International Standards are ISO 16877, ISO 16872 and ISO 3076. In future it is intended to implement the results on toughness derived in this document in new standards. Eleven steels, provided by four manufacturers, were tested to find a test regime on sub-size specimens and requirements on the notch impact toughness values at design temperature which resulted out of the tests. These requirements are adjusted to the toughness values of full size ISO-V specimens. NOTE 2 The requirements are also valid for other cross sections of the chain than round.