大口径机枪枪管内膛烧蚀行为与微观机理

Ablation Behavior and Microscopic Mechanism of Large-caliber Machine Gun Barrel

为进一步探究枪炮身管内膛烧蚀机理,采用扫描电子显微镜、透射电镜等方法对比分析了现用大口径枪钢30SiMn2MoV与新型长寿命枪钢MPS700V内膛烧蚀形貌与微观组织特征,在此基础上,通过促进点燃试验对比了两种枪钢烧蚀行为,揭示了枪管内膛烧蚀的组织演化规律与微观机理。寿终内膛组织分析表明,两种枪管烧蚀裂纹尖端同时形成三个区域,分别为硫化物区、氧化物区和基体区,其中氧化物区中发现熔化非晶氧化物,MPS700V的氧化物区和硫化物区厚度均小于30SiMn2MoV。烧蚀模拟实验结果表明:直径为1~10 mm的MPS700V试样的烧蚀临界压力比相同尺寸下的30SiMn2MoV试样高30%以上;直径3.2 mm镀铬MPS700V试样的烧蚀临界压力比相同尺寸的镀铬30SiMn2MoV高39%以上;新型长寿命枪钢MPS700V的抗烧蚀性能优于现用枪钢30SiMn2MoV。烧蚀试样组织分析表明,与寿终内膛烧蚀组织相似,两种枪钢在模拟烧蚀后均形成氧化物与树枝晶。通过对比寿终枪管内膛与促进点燃下烧蚀的热力学、动力学及组织特征,提出枪管内膛烧蚀由高温高压火药燃气下内膛表面微区发生金属燃烧导致,并建立了相应的演化模型。

In order to further explore the ablation mechanism of gun barrels,the ablation morphology and microstructure characteristics of the typical gun made of steel 30SiMn2MoV and the new developed long-life gun made of steel MPS700V were comparatively studied using scanning electron microscopy,transmission electron microscopy and other methods.Based on this,the evolution mechanism of the two ablated steel gun barrels was revealed by comparing the different ablation performances through ignition tests.The microstructure of the two ablated gun barrels showed that three different zones appeared at the crack tip,namely sulfide zone,oxide zone and matrix zone,and that molten amorphous oxides were found in the oxide zone.The thickness of the oxide zone and sulfide zone in MPS700V barrel was less than those in 30SiMn2MoV barrel.The ablation simulation experiments showed that the critical ablation pressure of MPS700V barrel with a diameter of 1-10 mm was more than 30%higher than that of 30SiMn2MoV barrel with the same size.The critical ablation pressure of the chrome-plated MPS700V sample with a diameter of 3.2 mm was more than 39%higher than that of the chrome-plated 30SiMn2MoV sample with the same size.So the anti-ablation performance of MPS700V steel is better than 30SiMn2MoV steel.It was also found that oxides and dendrites were observed both in 30SiMn2MoV steel and MPS700V steel after the ablation simulation tests,which were similar as the structure of the failed gun barrels.By comparing the microstructure,thermodynamics and kinetics characteristics of failed gun barrels and the samples under promoted ignition,it is proposed that the ablation of the gun barrels is caused by the combustion of gun steels in the micro zones on the barrel surface under high-temperature and high-pressure conditions,and the corresponding microstructure evolution model based on micro combustion is proposed.