Theoretical and Experimental Research on Dimensional Shrinkage of MFFF 17-4PH Products

doi:10.12068/j.issn.1005-3026.2025.20240013

Abstract

Abstract:

The dimensional shrinkage of the green sample treated by metal fused filament fabrication （MFFF） occurs during debinding/sintering process， affecting the forming accuracy and practical application. In order to clarify the shrinkage mechanism and put forward effective solutions， a theoretical model of the dimensional shrinkage rate of sintered samples was first established， and the dimensional changing process was theoretically analyzed. Then， a sintered sample of 17-4PH stainless steel was formed， and the microstructure of its cross-section was determined using scanning electron microscope （SEM）. Through the comparison between the theoretical and experimental results， the correctness of the proposed model was verified. Finally， the sensitivity of the model was analyzed， and the influence of the sintering temperature rise rate， maximum temperature holding time， and apparent density of the green sample on the dimensional shrinkage rate of MFFF samples was discussed. The results show that the dimensional shrinkage rate of the samples is anisotropic （the one in the vertical direction is slightly larger than that in the horizontal direction）. The apparent density of the green sample has the most significant effect on the dimensional shrinkage rate of the sintered samples， followed by the sintering temperature rise rate and maximum temperature holding time.

Key words: metal fused filament fabrication（MFFF）, dimensional shrinkage rate, 17-4PH stainless steel, theoretical analysis, experimental research

CLC Number:

TH 164

Shi-jie JIANG, Fei WANG, Shu-guang LI, Zi-zhao XU. Theoretical and Experimental Research on Dimensional Shrinkage of MFFF 17-4PH Products[J]. Journal of Northeastern University(Natural Science), 2025, 46(10): 104-112.

Figures/Tables 16

Fig.1 Schematic diagram of sample debinding/ sintering process

Table 1 Chemical composition of BASF 17-4PH

C	O	Cr	Fe	Ni	Cu
31.39	7.48	11.41	45.47	2.28	1.97

Fig.2 Schematic diagram of sample

Table 2 Main process parameters setting

参数	数值
喷嘴直径/mm	0.4
挤出宽度/mm	0.48
喷嘴温度/℃	240
成型速度/(mm∙s^-1)	15
层高/mm	0.12
重叠/%	15
填充率/%	100
床温/℃	90

Table 3 Catalytic debinding parameters setting

过程	腔体温度	进酸温度	尾气温度	用气流量	风扇转速	进酸量	时间
过程	℃	℃	℃	cm³·min^-1	r∙min^-1	mL∙min^-1	min
加热	105	150	145	3 000	1 000	0	45
前冲洗	105	150	145	3 000	1 000	0	30
脱脂	105	150	145	3 000	1 000	0.5	600
后冲洗	120	150	145	3 000	1 000	0	90

Table 4 Thermal debinding and sintering parameters

编号	温度	时间	工艺类型	进气量	气体
编号	℃	min	工艺类型	cm³·min^-1	气体
1	600	300	负压脱脂	2 000	Ar
2	600	60	负压脱脂	2 000	Ar
3	1 100	200	真空内烧	0	Ar
4	1 100	60	真空内烧	0	Ar
5	1 300	120	分压烧结	2 500	Ar
6	80	300	冷却	500	Ar

Fig.3 Theoretical results of dimensional shrinkage rate in x,y directions

Table 5 Theoretical and experimental results of dimensional shrinkage rate in x， y directions

样件	生坯样件尺寸/mm		烧结样件尺寸/mm		实验收缩率/%		理论收缩率/%	误差/%
样件	x 方向	y 方向	x 方向	y 方向	x 方向	y 方向	理论收缩率/%	x 方向	y 方向
S1-i	15.02	15.12	12.52	12.37	16.64	18.19	17.25	3.51	5.44
S2-i	15.03	15.05	12.62	12.31	16.03	18.21		7.05	5.54
S3-i	15.08	15.07	12.54	12.44	16.84	17.45		2.36	1.17
S4-i	15.03	15.13	12.56	12.32	16.43	18.57		4.73	7.67
S5-i	15.04	15.08	12.7	12.36	15.56	18.04		9.81	4.56

Fig.4 Theoretical results of dimensional shrinkage rate in z direction

Table 6 Theoretical and experimental results of dimensional shrinkage rate in z direction

样件 (i=5)	生坯样件 $z$ 方向尺寸/mm	烧结样件 $z$ 方向尺寸/mm	实验收缩率/%	理论收缩率/%	误差/%
S1-i	4.06	3.25	19.95	18.28	9.14
S2-i	4.12	3.28	20.39		11.53
S3-i	4.05	3.23	20.25		10.76
S4-i	4.11	3.31	19.46		6.48
S5-i	4.09	3.29	19.56		7.00

Table 6 Theoretical and experimental results of dimensional shrinkage rate in z direction

样件 (i=5)	生坯样件 $z$ 方向尺寸/mm	烧结样件 $z$ 方向尺寸/mm	实验收缩率/%	理论收缩率/%	误差/%
S1-i	4.06	3.25	19.95	18.28	9.14
S2-i	4.12	3.28	20.39		11.53
S3-i	4.05	3.23	20.25		10.76
S4-i	4.11	3.31	19.46		6.48
S5-i	4.09	3.29	19.56		7.00

Fig.5 Appearance, cross-section, and microstrucure of MFFF samples

Table 7 Sensitivity test parameters setting

参数	最小值X₁	默认值	最大值X₂
烧结升温速率/（℃∙min^-1）	1	2	4
最高温度保持时间/h	1	2	3
生坯样件表观密度/（g∙cm^-3）	2.9	3.9	4.9

Fig.6 Effect of different sintering temperature rise rates on dimensional shrinkage rate

Fig.7 Effect of different maximum temperature holding time on dimensional shrinkage rate

Fig.8 Effect of apparent density of green sample on dimensional shrinkage rate

Table 8 Sensitivity of model to different parameters

方向	参数	参数最小值 $X 1$	$Y 1$ /%	参数最大值 $X 2$	$Y 2$ /%	相对变化率 $Y 2 - Y 1 Y 1 / X 2 - X 1 X 1$ /%
x,y	烧结升温速率/（℃∙min^-1）	1	27.69	4	11.53	19.45
	最高温度保持时间/h	1	15.29	3	19.08	12.39
	生坯样件表观密度/（g∙cm^-3）	2.9	19.51	4.9	14.86	35.75
z	烧结升温速率/（℃∙min^-1）	1	29.24	4	12.19	19.44
	最高温度保持时间/h	1	16.15	3	20.15	12.38
	生坯样件表观密度/（g∙cm^-3）	2.9	20.76	4.9	15.66	36.85

Table 8 Sensitivity of model to different parameters

方向	参数	参数最小值 $X 1$	$Y 1$ /%	参数最大值 $X 2$	$Y 2$ /%	相对变化率 $Y 2 - Y 1 Y 1 / X 2 - X 1 X 1$ /%
x,y	烧结升温速率/（℃∙min^-1）	1	27.69	4	11.53	19.45
	最高温度保持时间/h	1	15.29	3	19.08	12.39
	生坯样件表观密度/（g∙cm^-3）	2.9	19.51	4.9	14.86	35.75
z	烧结升温速率/（℃∙min^-1）	1	29.24	4	12.19	19.44
	最高温度保持时间/h	1	16.15	3	20.15	12.38
	生坯样件表观密度/（g∙cm^-3）	2.9	20.76	4.9	15.66	36.85

References 15

[1]	Singh P， Balla V K， Gokce A， et al. Additive manufacturing of Ti-6Al-4V alloy by metal fused filament fabrication （MF3）： producing parts comparable to that of metal injection molding［J］. Progress in Additive Manufacturing， 2021， 6（4）： 593-606.
[2]	Singh G， Missiaen J M， Bouvard D， et al. Additive manufacturing of 17-4 PH steel using metal injection molding feedstock： analysis of 3D extrusion printing， debinding and sintering［J］. Additive Manufacturing， 2021， 47： 102287.
[3]	German R M. Sintering： from empirical observations to scientific principles［M］. Oxford： Butterworth-Heinemann， 2014： 153-161.
[4]	Caminero M Á， Romero Gutiérrez A， Chacón J M， et al. Effects of fused filament fabrication parameters on the manufacturing of 316L stainless-steel components： geometric and mechanical properties［J］. Rapid Prototyping Journal， 2022， 28（10）： 2004-2026.
[5]	Abe Y， Kurose T， Santos M V， et al. Effect of layer directions on internal structures and tensile properties of 17-4PH stainless steel parts fabricated by fused deposition of metals［J］. Materials， 2021， 14（2）： 243-255.
[6]	Quarto M， Carminati M， D’Urso G. Density and shrinkage evaluation of AISI 316L parts printed via FDM process［J］. Materials and Manufacturing Processes， 2021， 36（13）： 1535-1543.
[7]	Liu B， Wang Y X， Lin Z W， et al. Creating metal parts by fused deposition modeling and sintering［J］. Materials Letters， 2020， 263： 127252.
[8]	Olevsky E A. Theory of sintering： from discrete to continuum［J］. Materials Science and Engineering： R： Reports， 1998， 23（2）： 41-100.
[9]	Braginsky M， Tikare V， Garino T J， et al. Three-dimensional simulation of sintering using a continuum modeling approach［R］. Albuquerque： Sandia National Laboratories， 2003.
[10]	Petersson A， Ågren J. Constitutive behaviour of WC-Co materials with different grain size sintered under load［J］. Acta Materialia， 2004， 52（7）： 1847-1858.
[11]	Kuczynski G. The mechanism of densification during sintering of metallic particles［J］. Acta Metallurgica， 1956， 4（1）： 58-61.
[12]	Scherer G W. Sintering inhomogeneous glasses： application to optical waveguides［J］. Journal of Non-Crystalline Solids， 1979， 34（2）： 239-256.
[13]	De Jonghe L C， Chu M Y， Lin M K F. Pore size distribution， grain growth， and the sintering stress［J］. Journal of Materials Science， 1989， 24： 4403-4408.
[14]	German R M. Coarsening in sintering： grain shape distribution， grain size distribution， and grain growth kinetics in solid-pore systems［J］. Critical Reviews in Solid State and Materials Sciences， 2010， 35（4）： 263-305.
[15]	Fukuyama H， Higashi H， Yamano H. Thermophysical properties of molten stainless steel containing 5% B4C［J］. Nuclear Technology， 2019， 205（9）： 1154-1163.