CN112362473A - 一种异种钢焊接接头安全性评价方法 - Google Patents

一种异种钢焊接接头安全性评价方法 Download PDF

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CN112362473A
CN112362473A CN202011189658.3A CN202011189658A CN112362473A CN 112362473 A CN112362473 A CN 112362473A CN 202011189658 A CN202011189658 A CN 202011189658A CN 112362473 A CN112362473 A CN 112362473A
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刘福广
李勇
常哲
杨二娟
王博
米紫昊
王艳松
刘刚
韩天鹏
张周博
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Abstract

本发明公开了一种异种钢焊接接头安全性评价方法，以机组的实际运行情况为基础，选择异种钢接头中受力情况比较复杂的接头进行取样，通过接头的组织性能检验，以异种钢接头的性能变化趋势和组织老化特征为依据，可以对超(超)临界机组异种钢焊接接头进行综合评估，提早发现接头的早期失效倾向，减少因异种钢焊接接头早期失效导致的非计划停机，对增加电厂效益具有重要的指导意义。

Description

一种异种钢焊接接头安全性评价方法
技术领域
本发明属于超(超)临界机组锅炉异种钢新材料技术领域，具体涉及一种异种钢焊接接头安全性评价方法。
背景技术
根据目前国内外异种钢焊接接头的早期研究和使用情况得知，采用Ni基焊材的异种钢焊接接头可以在一定程度上抑制“碳迁移”现象，有效避免由于贫碳软化层的存在造成接头的蠕变强度降低，并且由于Ni基焊材的热膨胀系数介于合金钢和奥氏体不锈钢之间，与铁素体钢接近，可以减少热应力造成的异种钢接头的早期失效倾向，提高接头的使用寿命，所以当前被广泛应用到铁素体和奥氏体耐热钢的连接中。但是从Ni基过渡异种钢焊接接头的使用现状来看，接头在高温高压的长期运行过程中，Ni基过渡焊接接头仍然会在铁素体钢侧熔合线处出现早期失效，一般出现Ni基过渡异种钢焊接接头出现早期失效的时间为7～10年，这种早期失效是否与熔合线处析出相的形状、大小及分布情况和界面形貌有关，目前的研究结果还不一致；关于Ni基过渡异种钢焊接接头焊后是否需要进行热处理还存在一定的争议；此外，在Ni基过渡异种钢焊接接头的长期高温运行后，目前尚没关于接头的较为统一的老化损伤特征评定方法和有效的金属监督措施。因此，有必要对异种钢焊接接头的组织老化损伤特征及安全性进行研究很评价。
发明内容
为了克服上述现有技术存在的问题，本发明的目的在于提供一种异种钢焊接接头安全性评价方法，能够对超(超)临界机组新材料Ni基过渡异种钢焊接接头高温运行过程中的组织变化趋势进行预知、预测，有效指导现场安装、检修工艺的制定，为今后异种钢焊接接头的组织老化损伤特征的评定方法和金属监督提的制定提供技术支持。
为达到以上目的，本发明采用如下技术方案：
一种异种钢焊接接头安全性评价方法，包括如下步骤：
(1)对接头附近的结构和锅炉的运行情况进行详细调研；
(2)对异种钢焊接接头进行现场检查；
(3)根据以上调研结果和异种钢焊接接头的现场检查结果，抽取异种钢焊接接头中受力情况复杂的接头进行现场割管取样；
(4)对异种钢接头的安全性进行评估，具体为如下：
根据试验得出的异种钢焊接接头的组织与性能变化趋势和老化损伤特征，对取样接头的安全性评估应进行如下检验：①对取样接头进行力学性能检验，检验内容包括拉伸性能、冲击、布氏硬度及显微硬度；②对取样接头进行组织检验，检验内容包括光学金相组织检验和扫描电子显微镜分析，检验合金钢侧熔合线附近区域及合金钢侧热影响区，对于合金钢与奥氏体钢组合，应重点对熔合线附近的Ⅰ型碳化物和蠕变孔洞进行检查，根据合金钢侧熔合线Ⅰ型碳化物的大小、形貌及蠕变孔洞的大小和连接情况，以及热影响区中是否出现沿氧化缺口扩展的沿晶裂纹，对异种钢接头的界面安全性进行评估；此外，还应检验合金钢侧热影响区中是否出现“白亮”软化带及细晶区中是否出现了蠕变孔洞的连接；针对含HR3C钢的异种钢接头中在热影响区及母材中是否出现了网状沿晶碳化物；因此，若异种钢焊接接头出现如下特征之一则表明焊接接头存在安全隐患：(1)沿合金钢侧熔合线出现呈线状分布的大颗粒Ⅰ型碳化物；(2)由Ⅰ型碳化物形核、长大的蠕变孔洞发生连接；(3)热影响区中出现沿氧化缺口扩展的沿晶裂纹；(4)在合金钢侧热影响区中出现“白亮”软化带；(5)细晶区中出现密度较高的蠕变孔洞并开始连接；(6)含HR3C钢的异种钢接头中在热影响区及母材中出现了网状沿晶碳化物；其中第(1)～(3)对目前应用较多的合金钢与奥氏体钢组合具有普遍的适用性，而(4)、(5)则主要针对含有T91、T92马氏体耐热钢的异种钢组合，(6)则主要针对含有HR3C钢的异种钢接头。
优选地，步骤(1)所述的对接头附近的结构和锅炉的运行情况进行详细调研，调研内容包括接头附近的结构几何尺寸、蒸汽参数、累计运行时间、启停次数及每次停机的时间，实际运行温度、压力及温度、压力的波动范围，超设计参数运行的温度、压力及在这一压力下的运行时间，接头的制造工艺。
优选地，步骤(2)所述的对异种钢焊接接头进行现场检查，检查内容包括：①检查焊接接头部件的安装记录，是否存在不适当的支吊架会对异种钢焊接接头造成附加应力；②是否存在有碍于接头膨胀的结构；③对机组运行后进行过更换或检修的接头进行检查。
与现有技术相比，本发明的优势在于：
1、本发明提出的新材料Ni基过渡异种钢焊接接头的组织老化损伤特征研究及安全性评价方法可以对超(超)临界机组异种钢新材料焊接接头高温长期运行后的金属监督起到极大的指导作用。
2、本发明提出的新材料Ni基过渡异种钢焊接接头的组织老化损伤特征研究及安全性评价方法可以对超(超)临界机组异种钢焊接接头进行综合评估，提早发现接头的早期失效倾向，减少因异种钢焊接接头早期失效导致的非计划停机，对增加电厂效益具有重要的指导意义。
附图说明
图1为某电厂T91+HR3C现场取样焊接接头扫描电镜图。
图2为某电厂12Cr1MoV+12Cr18Ni12Ti现场取样接头扫描电镜图。
具体实施方式
为使本发明更加明显易懂，以下结合附图和具体实施案例对本发明作如下详细说明：
实施案例1：如图1所示，通过对某电厂3号机组三级过热器T91+HR3C焊接接头现场取样的合金钢侧熔合界面显微组织分析结果，从图1中可以看出，T91侧界面上虽然出现了线状排列的Ⅰ型碳化物，但是尺寸非常小(0.1μm左右)，且没有发现蠕变孔洞；由于机组运行时间较短，合金钢侧热影响区中未发现“白亮”带和蠕变孔洞，氧化缺口尚不明显；HR3C热影响区及母材中的碳化物尚未连接成连续的网状。所以评估认为某电厂的取样异种钢接头界面尚未出现老化损伤，无安全隐患。
实施案例2：如图2所示，通过对某电厂2号机组高温再热器取样管异种钢12Cr1MoV+12Cr18Ni12Ti焊接接头现场取样的界面附近显微组织分析结果，从图2中可以看出，该现场接头的熔合线处碳化物呈短棒状，交错沿熔合线分布，热影响区晶界处都出现了较多的蠕变孔洞，部分孔洞开始发生连接，参考本发明的试验研究结果，认为该厂的异种钢焊接接头已经存在较大程度的蠕变损伤，存在安全隐患。

Claims (3)

1.一种异种钢焊接接头安全性评价方法，其特征在于：包括如下步骤：
(1)对接头附近的结构和锅炉的运行情况进行详细调研；
(2)对异种钢焊接接头进行现场检查；
(3)根据以上调研结果和异种钢焊接接头的现场检查结果，抽取异种钢焊接接头中受力情况复杂的接头进行现场割管取样；
(4)对异种钢接头的安全性进行评估，具体为如下：
根据试验得出的异种钢焊接接头的组织与性能变化趋势和老化损伤特征，对取样接头的安全性评估应进行如下检验：①对取样接头进行力学性能检验，检验内容包括拉伸性能、冲击、布氏硬度及显微硬度；②对取样接头进行组织检验，检验内容包括光学金相组织检验和扫描电子显微镜分析，检验合金钢侧熔合线附近区域及合金钢侧热影响区，对于合金钢与奥氏体钢组合，应重点对熔合线附近的Ⅰ型碳化物和蠕变孔洞进行检查，根据合金钢侧熔合线Ⅰ型碳化物的大小、形貌及蠕变孔洞的大小和连接情况，以及热影响区中是否出现沿氧化缺口扩展的沿晶裂纹，对异种钢接头的界面安全性进行评估；此外，还应检验合金钢侧热影响区中是否出现“白亮”软化带及细晶区中是否出现了蠕变孔洞的连接；针对含HR3C钢的异种钢接头中在热影响区及母材中是否出现了网状沿晶碳化物；因此，若异种钢焊接接头出现如下特征之一则表明焊接接头存在安全隐患：(1)沿合金钢侧熔合线出现呈线状分布的大颗粒Ⅰ型碳化物；(2)由Ⅰ型碳化物形核、长大的蠕变孔洞发生连接；(3)热影响区中出现沿氧化缺口扩展的沿晶裂纹；(4)在合金钢侧热影响区中出现“白亮”软化带；(5)细晶区中出现密度较高的蠕变孔洞并开始连接；(6)含HR3C钢的异种钢接头中在热影响区及母材中出现了网状沿晶碳化物；其中第(1)～(3)对合金钢与奥氏体钢组合具有适用性，而(4)、(5)则针对含有T91、T92马氏体耐热钢的异种钢组合，(6)则针对含有HR3C钢的异种钢接头。
2.如权利要求1所述的一种异种钢焊接接头安全性评价方法，其特征在于：步骤(1)所述的对接头附近的结构和锅炉的运行情况进行详细调研，调研内容包括接头附近的结构几何尺寸、蒸汽参数、累计运行时间、启停次数及每次停机的时间，实际运行温度、压力及温度、压力的波动范围，超设计参数运行的温度、压力及在这一压力下的运行时间，接头的制造工艺。
3.如权利要求1所述的一种异种钢焊接接头安全性评价方法，其特征在于：步骤(2)所述的对异种钢焊接接头进行现场检查，检查内容包括：①检查焊接接头部件的安装记录，是否存在不适当的支吊架会对异种钢焊接接头造成附加应力；②是否存在有碍于接头膨胀的结构；③对机组运行后进行过更换或检修的接头进行检查。
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Cited By (2)

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CN113111507A (zh) * 2021-04-08 2021-07-13 西安热工研究院有限公司 一种锅炉严重超温后蒸汽系统材质安全性评估的方法
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