Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals
Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals
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DOI：
10.1007/s40194-020-00895-2
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发表时间：
2020-03
影响因子：
2.1
通讯作者：
Maximilian Thomas;F. Vollert;J. Weidemann;J. Gibmeier;A. Kromm;T. Kannengiesser
中科院分区：
文献类型：
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作者：
Maximilian Thomas;F. Vollert;J. Weidemann;J. Gibmeier;A. Kromm;T. Kannengiesser
本研究的主题是如何，以及在何种程度上，Varestraint/Transvarestraint测试结果的影响，测试参数和评价方法的特点。几种不同的高合金马氏体LTT（低相变温度）填料材料，CrNi和CrMn型，被选择用于检查，由于其相当独特的凝固开裂行为，这引起了人们的兴趣后，以前的研究。首先，使用标准方法测量不同工艺参数设置对凝固开裂响应的影响。随后，对样本进行微焦点X射线计算机断层扫描（μCT）。结果一致表明，表面下开裂程度显著但程度不同。不同的初级凝固类型被发现使用波长色散X射线（WDX）分析进行填充金属与不同的Cr/Ni当量比。这方面被认为是CrNi型和CrMn型材料在开裂特性方面的主要差异。结果表明，在现代高性能合金的测试中，一套标准的Varestraint测试参数可能不适用于所有材料。此外，为了适当地适应不同的固化类型，必须考虑次表面开裂。
The subject of this study is how, and to what extent, Varestraint/Transvarestraint test results are influenced by both testing parameters and characteristics of evaluation methods. Several different high-alloyed martensitic LTT (low transformation temperature) filler materials, CrNi and CrMn type, were selected for examination due to their rather distinctive solidification cracking behaviour, which aroused interest after previous studies. First, the effects of different process parameter sets on the solidification cracking response were measured using standard approaches. Subsequently, microfocus X-ray computer tomography (μCT) scans were performed on the specimens. The results consistently show sub-surface cracking to significant yet varying extents. Different primary solidification types were found using wavelength dispersive X-ray (WDX) analysis conducted on filler metals with varying Cr/Ni equivalent ratios. This aspect is regarded as the main difference between the CrNi- and CrMn-type materials in matters of cracking characteristics. Results show that when it comes to testing of modern high-performance alloys, one set of standard Varestraint testing parameters might not be equally suitable for all materials. Also, to properly accommodate different solidification types, sub-surface cracking has to be taken into account.