对含1.5%铜、铬含量在0.0%到2.0%之间的亚零冷激铸铁（使用液氮）进行了极限抗拉强度和断裂韧性试验。研究发现，极限抗拉强度和断裂韧性都高度依赖于铬含量以及试样在铸件上的位置。断裂韧性和极限抗拉强度之间没有明确的关系。

ULTIMATE TENSILE STRENGTH AND FRACTURE TOUGHNESS EXPERIMENTS WERE CONDUCTED INVOLVING SUB-ZERO CHILLED (USING LIQUID NITROGEN) CAST IRON CONTAINING 1.5%CU, AND CHROMIUM CONTENTS RANGING FROM 0.0% TO 2.0%. IT WAS FOUND THAT BOTH ULTIMATE TENSILE STRENGTH AND FRACTURE TOUGHNESS ARE HIGHLY DEPENDENT ON THE CHROMIUM CONTENT AS WELL AS THE LOCATION ON THE CASTING FROM WHERE THE TEST SPECIMENS ARE TAKEN. NO DEFINITE RELATIONSHIP WAS FOUND BETWEEN FRACTURE TOUGHNESS AND ULTIMATE TENSILE STRENGTH.