耐熱鋼の研究(XI)

含Ti, B 11-25-6合金のWarm Workと加工を受けた材料の析出組織

抄録

In this report, the effect of "warm-work" and the variety of microstructure during precipitation for warm-worked material on 16-25-6 alloy containing Ti or B were studied.
There are three different compositions in the specimens. (#D1 #D2 and #D3) Sample #D1 contained 0.68% Ti, #D2 contained 1.86% Ti, and #D3 contained 0.085% B, based on 16 Cr-25 Ni-6 Mo alloy. The chemical compositions is shown in Table 1 in full detail.
After forged to bars, these samples were solution treated at 1150°C for #D1 and #D3, and at 1200°C for #D2 for 1 hour. Then the tensile-test pieces were made.
The warm working was made at 650°C by means of an Amsler's tensile-test machine.
The ratio of work was arrived at by computing the ratio of reductioh of area in all parts. After measuring of hardness and microtructure, these ramples were annealed at 650°C or 750°C from 1 hour to 500 hours. Then the change of hardness and microstructure by precipitation were measured.
The effect of Warm-working on strength of material of all samples of #D1, #D2, #D3 was ascertained by hardness measuring, even after annealing at 650°C or 750°C for 500 hours. The hardness of the warm-worked alloys after annealing at 650°C or 750°C for 500 hours was much higher than the hardness of the same samples only aged at same temperature for 500 hours without the working process.
When the element Ti was added to, #D1 (0.68% Ti) and #D2 (1.86% Ti) almost similar changes occurred during testing. Althongh the warm-working effect was evident on #D1, #D2, two samples containing Ti showed much precipitation-hardening during heating whether they were warm-worked or not. But, sample #D3 containing B showed remarkable precipitation hardening only when it was warm-worked before aging. So the warm-working process was more effective on #D3.
The abnormal microstructure which appeared during heating after warm-working was also discussed in the full report.