一、引言 623钢为中碳多元含硼大截面铸钢,在35吨碱性平炉中冶炼,铝终脱氧,包内加入0.1％稀土矽铁,0.002-0.0025％硼铁。铸件经均匀化、正火、高温回火予先热处理,在最终调质处理后检验断口,断口试样截面积为160×160毫米~2。正常的断口应为纤维 I. INTRODUCTION 623 steel is a medium-carbon multi-element boron-bearing large-section cast steel. It is smelted in a 35-tonne alkaline open hearth and the aluminum is finally deoxygenated. The package contains 0.1% rare earth ferrosilicon and 0.002-0.0025% ferroboron. Casting by homogenization, normalizing, high temperature tempering preheat treatment, the final quenched after the test fracture, fracture cross-sectional area of ​​160 × 160 mm ~ 2. Normal fracture should be fiber