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对FV520B不锈钢零件的激光熔覆热影响区进行了组织特征分析,结合过冷奥氏体连续冷却转变(CCT)实验、模拟热影响区拉伸及冲击实验,研究了热影响区组织及力学性能的演变规律和机理.结果表明,热影响区可以按照组织演化特点分为4个特征区域:半熔区(A区),析出相溶解区(B区),完全奥氏体化区(C区)和部分奥氏体化区(D区).各区域均为马氏体组织,靠近界面区域的组织较为粗大,第二相发生溶解,硬度更高,固态相变点更低;距界面稍远区域回火马氏体增多,第二相未溶解,但有长大的趋势,硬度较低,固态相变点较高,接近原始材料.决定激光熔覆热影响区组织及力学性能的最主要因素是热循环的最高温度,最高温度越高,强度损失越大,固态相变点越低,相应硬度越高,延伸率及冲击功降低.
The microstructure of the heat affected zone of the FV520B stainless steel parts was analyzed. Combined with the CCT experiment, the tensile and impact experiments in the heat affected zone were simulated. The microstructure and mechanical properties of the heat affected zone The results show that the heat-affected zone can be divided into four characteristic zones according to the evolution of the structure: semi-molten zone (A zone), precipitation-dissolved zone (B zone), complete austenization zone (C zone ) And partially austenite zone (D zone), all of which are martensite, the structure near the interface is coarse, the second phase is dissolved, the hardness is higher and the solid state transition point is lower, Tempering martensite in the far area increased, the second phase did not dissolve, but grew up, the hardness was lower, the solid state transformation point was higher, close to the original material. The most important factor to determine the microstructure and mechanical properties of the laser heat affected zone The main factor is the maximum temperature of the thermal cycle, the higher the maximum temperature, the greater the loss of strength, the lower the solid state transformation point, the higher the corresponding hardness, the lower elongation and impact energy.