P91连铸钢坯的显微组织和残余应力分布与测试
Microstructures and residual stress of P91 continuous ingot
钟 文，石绍清，江自然，左 著，郑 峰
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作者单位：中南大学材料科学与工程学院；衡阳华菱钢管有限公司；中南大学衡钢钢管研究院
中文关键字：P91连铸钢坯； 显微组织； 残余应力
英文关键字：P91 continuous cast ingot; microstructure; residual stress
中文摘要：采用光学显微镜和扫描电子显微镜分析，表面硬度和残余应力测试，研究了P91高合金连铸钢坯在凝固后显微组织与残余应力的变化规律。研究结果表明：影响铸坯组织结构的主要因素是冷却速率及其在坯体中的位置。铸坯中心的组织为铁素体和马氏体，其硬度相对较低；远离中心，铁素体逐渐减少、消失，马氏体逐渐增多，其硬度也相应的逐渐增大。通过iXRD便携式残余应力测量仪测量出铸坯的残余应力，其结果为在中心受740 MPa的拉应力，边缘受435 MPa的压应力。
英文摘要：The function of microstructure and residual stress changes in samples taken from continuously casted P91 alloy ingot was studied by optical microscopy and scanning electron microscopy analysis, surface hardness and residual stress test. The result showed that, the major factor influencing the cast microstructure was the cooling rate and the position away from ingot casting center during solidification. In the center of the ingot, the microstructure was consisted of ferrite and martensite with low hardness, while away from the center towards surface, the volume fraction of ferrite was continuously reduced until disappear somewhere around middle portion where that of martensite being increased associating with ever-increased hardness. The residual stress was tested by iXRD residual stress testing instrument and the result presented was determined to be thermal stress with 740 MPa tensile stress appeared in the inner part (center) while 435 MPa compressive stress occurred in the outside (surface).