钼对S30432耐热钢组织和性能的影响

 为了明确是否应在国产S30432钢中加入钼,研究了0.32%Mo对S30432耐热钢组织和性能的影响及机理。利用SEM、TEM和Thermo-Calc软件研究了钼对S30432钢析出相和基体的影响;通过650 ℃高温瞬时拉伸试验和高温蠕变断裂试验研究钼对S30432钢高温力学性能的影响;采用电化学试验评价了钼的添加对S30432钢耐腐蚀性能的影响。结果表明,添加钼对S30432钢的高温力学性能和耐腐蚀性能有益。在S30432钢中添加0.32%Mo,提高了其650 ℃时的屈服强度和抗拉强度,延长了短时蠕变断裂时间并提高了断裂后的硬度。但长时蠕变后钼对S30432钢强度提高的作用不明显。含钼的S30432钢具有更高的自腐蚀电位、点蚀破裂电位和更低的晶间腐蚀敏感性。腐蚀形貌观察发现含钼钢中点蚀坑的数量较少、尺寸较小,晶间腐蚀程度较轻。

Effect of Mo on microstructure and properties of S30432 heat-resistant steel

In order to confirm whether Mo should be added to domestic S30432 steel,the effect and mechanism of 0.32% Mo addition on the microstructure and properties of S30432 heat-resistant steel were studied. SEM,TEM and Thermo-Calc software were used to study the influence of 0.32% Mo on the precipitates and matrix in S30432 steel. The effect of Mo on the mechanical properties of S30432 steel at high temperature was studied by instantaneous tensile test and creep rupture test at 650 ℃. The pitting corrosion resistance and intergranular corrosion resistance of Mo-free and Mo-containing S30432 were evaluated by electrochemical experiment. The results show that the addition of Mo is beneficial to the mechanical properties at high temperature and corrosion resistance of S30432 steel. Adding 0.32%Mo to S30432 steel improves the yield strength and tensile strength at 650 ℃,prolongs the creep rupture time of short-term creep at high temperature and increases the hardness. However,the effect of Mo on the improvement in strength of S30432 steel is not obvious after long-term creep. Compared with Mo-free steel,the self-corrosion potential and pitting rupture potential of Mo-containing S30432 steel are higher and the susceptibility of intergranular corrosion is lower. Corrosion morphology observation shows that there are fewer pitting pits with smaller size in the Mo-containing steel,and intergranular corrosion is less serious.