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1 同结晶器保护法有关的表面缺陷纵向表面裂纹一碳含量在0.08%～0.14%范围内的钢种特别容易出现纵裂纹.碳的影响归结于当δ铁素体在弯月面附近转变成奥氏体时产生相对较大的热收缩.它引起了凝固壳中的折皱.所以由此引起的结晶器/凝固壳缝隙不均匀,造成了局部热点.这些点集中了导致纵裂的拉伸应力.已证明由热撕裂形成的裂纹接近弯月面附近的凝固界面,这里的延性相当低.当凝固壳脱离(结晶器壁)时,其表面延性进一步逐渐降低.如果拉伸应力足够大,表层内裂纹随后可以扩展到上部冷却表面.
1 Longitudinal surface cracks associated with mold protection Surface defects Longitudinal cracks are particularly susceptible to steel with a carbon content in the range of 0.08% to 0.14%. The effect of carbon is attributed to the transformation of δ ferrite near the meniscus into A relatively large heat shrinkage occurs in austenite, which causes wrinkles in the solidification shell, so the resulting irregularities in the crystallizer / solidification shell gaps result in localized hot spots, which concentrate the stretching that causes longitudinal cracking Stress. The crack formed by hot tearing has been shown to be close to the solidification interface near the meniscus, where the ductility is quite low and the surface ductility is further reduced as the solidified shell escapes (mold wall) .If the tensile stress is large enough , Surface cracks can then be extended to the upper cooling surface.