30CrMo钢大直径厚壁压力气瓶淬火过程数值模拟

Numerical simulation on quenching process of the large-diameter thick-wall gas cylinder of 30CrMo steel

采用有限元数值模拟技术,建立了30Cr Mo钢大直径厚壁压力气瓶在淬火过程中内部温度场、组织相变场和应力应变场相互耦合的数学模型,给出了气瓶在槽内浸水与内表面径向间歇喷雾外表面连续喷水2种淬火工艺下的温度、组织及应力的分布与演化规律。数值模拟研究结果表明,在槽内浸水淬火冷却过程中,气瓶瓶体内外表面温度差异较大,存在较大温度梯度,气瓶在淬火过程中的应力峰值较大,容易引起气瓶发生较大变形,且瓶体不能完全淬透,马氏体转变量较少;气瓶内表面径向间歇喷雾外表面连续喷水淬火工艺可使气瓶的内外表面冷却强度更加合理,进而降低其内外表面的温度梯度,减小其淬火应力峰值,消除其淬火变形,改善其组织分布,从而保证瓶体组织和硬度的均匀性。

A three dimensional coupling model on temperature, microstructure and stress of the 30 Cr Mo large- diameter and thick-wall gas cylinder during quenching process was built with use of finite element numerical simulation technology. Temperature distribution, phase transition and stresses variation of the gas cylinder during quenching processes were investigated. Two quenching processes are compared, i.e. quenching immersed in a water groove and quenching intermittent sprayed inside with continuous water sprayed outside on the cylinder respectively. Numerical simulation results show that the temperature difference between the internal surface and the outside surface of the cylinder was very large and a higher peak value of quenching heat stress emerged during quenching immersed in the water groove, which would lead to a large deformation of the gas cylinder and the shell could not be through hardened completely. The cooling intensity was reasonable under the quenching process by intermittent sprayed inside with continuous water sprayed outside on the gas cylinder.The temperature gradient and the quenching stress were reduced, the quenching distortion was eliminated, the microstructure distribution was improved and the uniformity of microstructure and hardness of the gas would be realized during this quenching process.