用作热电偶保护管的高温抗氧化合金介绍
网络整理 2022-06-23

制造有限公司用于生产测量高温的材料有GH3030、GH3039、GH140、Inconel 600、3YC52、HR1300等,本文介绍这些高温抗氧化合金材料的性能和力学性能。

金属材料的抗高温氧化腐蚀性能主要是靠在高温下形成致密的保护膜来实现,保护膜既可阻止氧、硫等腐蚀性气体向基体中扩散,又能阻止金属离子向外扩散。常用的保护膜主要有Cr2O3和Al2O3等。当使用温度高于1100-115-℃时,Cr2O3剥落严重,因此,该种高温合金短期最高使用温度应低于1200℃。典型高温耐热合金有GH3030、GH3039、GH140、Inconel 600、3YC52等,制造有限公司常用这些合金材料生产特殊用途的。Al2O3保护层具有比Cr2O3更佳的抗氧化能力。当温度高达1200-1300℃,Al2O3保护层仍不易剥落,且形成Al2O3所需的平衡氧分压明显低于Cr2O3的分压。如Fe-Cr-Al电热合金含有高达5%-8%(质量分数)的Al,能在高温形成单一Al2O3保护层,从而具有优异的抗氧化腐蚀性能。可是这样合计为铁素基体,脆性很大,高温强度低,限制了其应用。为了提高合金在1200-1300℃的抗氧化性能,开发出一些高温下能形成Al2O3的高温合金,国外典型合金有Haynes Alloy 214、эп747、Inconel 602、Inconel 603等。重庆仪表材料研究所在国外合金基础上,通过提高Cr、Al含量,并采用晶界精华和强化技术,研制出一种新型抗氧化高温耐热合金3YC52,其主要原因是在高温下除形成Al2O3、Cr2O3的混合氧化膜外,还能形成致密、单一α-Al2O3保护膜。3YC52合金与国外同类合金在1100℃、1300℃抗氧化性能对比(见图1和图2)和氧化层的SEM和EPMA分(见图3和图4)。

3YC52与同类合金1100℃高温氧化曲线                  3YC52与同类合金1300℃高温氧化曲线
图1    3YC52与同类合金1100℃高温氧化曲线                                图2    3YC52与同类合金1300℃高温氧化曲线

1300℃/500h下3YC52氧化层的SEM和EPMA分析
图3     1300℃/500h下3YC52氧化层的SEM和EPMA分析

1300℃/500h下Alloy 214氧化层的SEM和EPMA分析
图4     1300℃/500h下Alloy 214氧化层的SEM和EPMA分析

上述合金材料的研制成功,解决了高温环境中许多材料难题。但是在使用中发现上述材料出现变形问题。因此,如何能在保持高温氧化性能基础上,提高合金的高温强度,成为抗氧化合金技术进步的关键。技术人员在3YC52基础上,对材料和合金进行了重新设计,同时采用原位反应颗粒增强新技术,研制出能在高达1250-1350℃的温度下长期使用的氧化耐热合金HR1300。HR1300高温强度较国外同类合金提高30%以上。可用于各种氧化剂氧化腐蚀环境下使用的热电偶保护管、高温管道和高温静止件等。国内外常见高温耐热合金力学性能见表1。

表1   国内外常见高温耐热合金力学性能


高温合金材料               温度                 抗拉强度σb/MPa              屈服强度σ0.2/MPa               延伸率δ(%)
HR1230                      20℃                 866                                   390                                      48
                                   980℃               242                                   145                                      83
                                   1100℃             135                                   70                                        82
                                   1200℃             65                                     34                                        105
HR1300                      20℃                 680                                   340                                      45
                                   980℃               120                                   80                                        85
                                   1100℃             70                                     45                                        95
                                   1200℃             35                                     20                                        102
3YC52                         20℃                 650                                   358                                      55
                                   980℃               65                                     40                                        126
                                   1100℃             40                                     25                                        132
                                   1200℃             25                                     15                                        125
Alloy 214                    20℃                 958                                   565                                      43
                                   980℃               115                                   58                                        83
                                   1100℃             60                                     29                                        83
                                   1200℃             30                                     10                                        109
эп747                          20℃                600                                   300                                       50
                                   980℃               50                                     35                                         45
                                   1100℃             30                                     20                                         70
                                   1200℃             20                                     —                                         90
Inconel 800H              20℃                 566                                  245                                       49
                                   980℃               76                                     56                                        100
                                   1100℃             35                                     23                                        108
                                   1200℃             —                                     —                                          —
Inconel 601                20℃                 704                                   241                                      50
                                   980℃               90                                     74                                        100
                                   1100℃             45                                     41                                        120
                                   1200℃             35                                     13                                        121
Inconel 600                20℃                 662                                   282                                       45
                                   980℃               76                                     42                                        115
                                   1100℃             36                                     21                                        120
                                   1200℃             —                                      —                                         —
GH3030                      20℃                 756                                  355                                        41
                                   980℃               70                                     —                                         50
                                   1100℃             43                                     —                                         71
                                   1200℃             27                                     —                                         108
GH3039                      20℃                 820                                   —                                         46
                                   980℃                —                                    —                                         95
                                   1100℃              —                                    —                                          —
                                   1200℃              —                                    —                                          —

在特殊场合使用的热电偶使用寿命跟热电偶保护管材料有非常大的关系,每一种材料都需要在不同使用工况经实际应用验证后才能定型与热电偶生产中。在高温抗氧化合金应用中积累了大量经验,量体裁衣造仪表,这是热电偶使用寿命长且高性价比的秘密。

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